JP2011052434A

JP2011052434A - Method for replacing cross beam

Info

Publication number: JP2011052434A
Application number: JP2009201750A
Authority: JP
Inventors: Atsushi Fukui; 敦史福井; Keiichi Takeda; 圭一竹田
Original assignee: IHI Infrastructure Systems Co Ltd
Current assignee: IHI Infrastructure Systems Co Ltd
Priority date: 2009-09-01
Filing date: 2009-09-01
Publication date: 2011-03-17
Anticipated expiration: 2029-09-01
Also published as: JP5261327B2

Abstract

<P>PROBLEM TO BE SOLVED: To replace an end cross beam even if a space under a cross beam is restricted. <P>SOLUTION: In an I-beam bridge, the end edges of outer girders 4, 6 and an intermediate girder 5 are joined to each other through end cross beams 8a, 8b, respectively, and the end of the intermediate girder 5 and the end cross beams 8a, 8b are supported, through bearings 10, on beam supporting brackets 9b, 9a, 9c provided to the cross beam 3 of a steel bridge pier 1. While the outer girders 4, 6 and one end cross beam 8a are jacked up with jacks 20a, 20b, 20c on supports 17 for outer girder jackup and a first support 19a for end cross beam jackup which are provided to the cross beam 3, the other end cross beam 8b is replaced with a new end cross beam 21b. Then, the new other end cross beam 21b is jacked up with a jack on a second support for end cross beam jackup which is provided to the cross beam 3, and while the load is supported with the jack 20c, the one end cross beam 8a is replaced with a new one. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、桁橋における各主桁の桁端縁部同士を連結する横桁であって、且つ上記各主桁からの荷重を支承を介して橋脚側の桁受ブラケットへ伝えて支持させるようにしてある横桁を取り替えるために用いる横桁取替方法に関するものである。 The present invention is a horizontal girder that connects the girder edges of each main girder in a girder bridge, and the load from each main girder is transmitted to the girder bracket on the pier side via the support so as to be supported. The present invention relates to a cross-girder replacement method used for replacing a cross-girder.

鋼橋の形式の１つに、多主Ｉ桁橋があり、この種の多主Ｉ桁橋の一例としては、たとえば、首都高速道路等の都市部の高架橋で用いられている図３５（イ）（ロ）（ハ）及び図３６に示す如き３主Ｉ桁橋がある。 One type of steel bridge is a multi-main I-girder bridge. As an example of this type of multi-main I-girder bridge, for example, FIG. There are three main I girder bridges as shown in FIG.

これは、橋幅方向の両側に立設した一対の脚柱２と、橋幅方向に延びてその両端部を上記各脚柱２にそれぞれ一体に取り付けた横梁３とからなる門型の鋼製橋脚１を備えている。 This is made of a gate-shaped steel made up of a pair of pedestals 2 standing on both sides in the bridge width direction, and cross beams 3 extending in the bridge width direction and integrally attached to the respective pedestals 2 at both ends thereof. A pier 1 is provided.

更に、Ｉ桁からなる３本の主桁４，５，６を、橋幅方向に所要間隔で配置して、該各主桁４，５，６のうち、橋幅方向両端部の各主桁（以下、外主桁と云う）４，６の桁端はフルウェブとすると共に、橋幅方向中央部の主桁（以下、中主桁と云う）５の桁端には下部側に切欠き部７を設ける。且つ上記中主桁５における上記切欠き部７の上側の桁端より所要寸法離れた桁端縁部所要個所の両側面と、その両側に位置する上記各外主桁４，６の桁端より所要寸法離れた桁端縁部所要個所の上部内側面とを、上記鋼製橋脚１の横梁３と平行に橋幅方向に延びる別々の支承用の横桁（以下、端横桁と云う）８ａと８ｂを介しそれぞれ一体に接続した構成として、上記中主桁５の切欠き部７が設けてある桁端と、上記各端横桁８ａ，８ｂの橋幅方向の外側端部寄り位置とを、上記鋼製橋脚１の横梁３の各橋軸方向面の下部に突設した桁受ブラケット９ａ，９ｂ，９ｃの上側に、支承（シュー）１０を介して支持させた構成としてある。 Further, three main girders 4, 5 and 6 consisting of I-digits are arranged at a required interval in the bridge width direction, and among the main girders 4, 5 and 6, each main girder at both ends in the bridge width direction. (Below, referred to as the outer main girder) 4 and 6 girder ends are full webs, and the main girder (hereinafter referred to as the middle main girder) 5 in the center of the bridge width direction is notched to the lower side. A portion 7 is provided. In the middle main girder 5, both side surfaces of a required part of the girder edge that is away from the upper girder end of the notch 7 and girder ends of the outer main girder 4 and 6 located on both sides thereof Separate support cross beams (hereinafter referred to as end cross girders) 8a extending in the bridge width direction in parallel with the cross beam 3 of the steel pier 1 and the upper inner side surface of the required portion of the girder edge apart from the required dimension. And 8b, the girder end where the notch 7 of the middle main girder 5 is provided, and the position of the end lateral girder 8a, 8b near the outer end in the bridge width direction. The steel bridge pier 1 is supported by a support (shoe) 10 on the upper side of the girder brackets 9a, 9b, 9c projecting at the lower part of each bridge axial direction surface of the cross beam 3 of the steel pier 1.

かかる構成としてあるＩ桁橋によれば、上記鋼製橋脚１の横梁３に、上記各主桁４，５，６を、該横梁３の上下寸法内で受けさせることができるため、上記横梁３の上下端部の高さ位置と、上記各主桁４，５，６の上下端部の高さ位置を揃えることができて、建築限界等により桁高制限を受ける場合に有利な構成とすることができるようにしてある。なお、図３５（イ）（ロ）（ハ）及び図３６では図示する便宜上、上記鋼製橋脚１の横梁３及び各主桁４，５，６の上側に設ける床版の記載を省略してある。（以後の図も同様。）
ところで、近年、上記図３５（イ）（ロ）（ハ）及び図３６に示した如き構成を有するＩ桁橋では、老朽化に伴い、各支承１０の機能の劣化や、支承周りの損傷が指摘されてきている。 According to the I girder bridge having such a configuration, the main beam 4, 5, 6 can be received by the horizontal beam 3 of the steel pier 1 within the vertical dimension of the horizontal beam 3. The height positions of the upper and lower ends of the main girder and the height positions of the upper and lower ends of the main girders 4, 5 and 6 can be aligned. I can do it. 35 (a), (b), (c) and FIG. 36, the illustration of the floor slabs provided on the upper side of the cross beam 3 and the main girders 4, 5, 6 of the steel pier 1 is omitted for convenience of illustration. is there. (The same applies to the following figures.)
By the way, in recent years, in the I girder bridge having the structure shown in FIGS. 35 (a), (b), and (c) and FIG. 36, the function of each support 10 is deteriorated and the surroundings of the support are damaged due to aging. It has been pointed out.

そのために、上記各支承１０の取り替えによる機能回復と、支承周りの補強を行うことができる改修方法として、いわゆる主桁フルウェブ化工事が従来行われている（たとえば、非特許文献１参照）。 Therefore, a so-called main girder full web construction work has been conventionally performed as a repair method capable of performing functional recovery by replacing each of the bearings 10 and reinforcing the surroundings of the bearings (see, for example, Non-Patent Document 1).

上記主桁フルウェブ化工事は、たとえば、図３７（イ）（ロ）乃至図３９（イ）（ロ）（ハ）の手順で行うようにしてある。すなわち、先ず、図３７（イ）（ロ）に示す如く、図３５（イ）（ロ）（ハ）及び図３６に示したと同様の構成としてあるＩ桁橋における鋼製橋脚１の横梁３の下側に、橋軸方向に各主桁４，５，６の桁端の下方位置まで延びる幅広の増設横梁１１を配置して、その上端部を上記横梁３の下端部に一体に取り付けると共に、該増設横梁１１の橋幅方向の両端部を、両脚柱２にそれぞれ一体に固定する。この際、上記増設横梁１１の各橋軸方向面における上記各主桁４，５，６の真下となる位置には、予め、ジャッキアップ用受台１２ａ，１２ｂ，１２ｃを、対応する主桁４又は５又は６に沿わせて所要寸法突出させてそれぞれ設けておくようにする。なお、上記中主桁５の下方位置のジャッキアップ用受台１２ｂは、図３７（ロ）に示すように、該中主桁５の切欠き部７よりも支間中央側のフルウェブとなっている部分の下方位置まで突出させておくようにする。 The main girder full web construction is performed, for example, according to the procedure shown in FIGS. 37 (a) (b) to 39 (a) (b) (c). That is, first, as shown in FIGS. 37 (a) and (b), the cross beam 3 of the steel pier 1 in the I girder bridge having the same configuration as shown in FIGS. 35 (a), (b), and (c) and FIG. On the lower side, a wide additional horizontal beam 11 extending to the lower position of the girder ends of the main girders 4, 5 and 6 in the bridge axis direction is arranged, and its upper end is integrally attached to the lower end of the horizontal beam 3, Both ends in the bridge width direction of the additional horizontal beam 11 are fixed integrally to the two leg posts 2 respectively. At this time, jack-up cradles 12a, 12b, and 12c are placed in advance at the positions directly below the main girders 4, 5, and 6 on the surface of each bridge axis of the additional horizontal beam 11, respectively. Alternatively, the required dimensions are projected along 5 or 6, respectively. Note that the jack-up cradle 12b below the middle main girder 5 is a full web on the center side of the span with respect to the notch 7 of the middle main girder 5, as shown in FIG. Project to the lower position of the part.

次に、図３８（イ）（ロ）（ハ）に示すように、上記増設横梁１１の各ジャッキアップ用受台１２ａ，１２ｂ，１２ｃ上にそれぞれ設置したジャッキ１３により、上記すべての主桁４，５，６を同時にジャッキアップして、上記各主桁４，５，６に作用している荷重を、上記各ジャッキ１３及び各ジャッキアップ用受台１２ａ，１２ｂ，１２ｃを介して上記増設横梁１１に伝えて支持させるようにする。 Next, as shown in FIGS. 38 (a), (b), and (c), all the main girders 4 are formed by the jacks 13 respectively installed on the jack-up receiving bases 12a, 12b, and 12c of the additional lateral beam 11. , 5 and 6 are jacked up at the same time, and the load acting on the main girders 4, 5 and 6 is supplied to the additional horizontal beams via the jacks 13 and the jack-up cradles 12a, 12b and 12c. 11 to support.

次いで、上記のようにして、上記各ジャッキ１３によりすべての主桁４，５，６を同時にジャッキアップさせることで、隣接する主桁４と５及び主桁５と６の桁端縁部同士を接続している各端横桁８ａ，８ｂ、及び、上記鋼製橋脚１の横梁３の各橋軸方向面に既設の各桁受ブラケット９ａ，９ｂ，９ｃとその上側の各支承１０には、上記各主桁４，５，６からの荷重が掛からなくなるため、この状態で、上記横梁３より上記既設の各桁受ブラケット９ａ，９ｂ，９ｃ及び既設の各支承１０を撤去するようにする。 Next, as described above, all the main girders 4, 5 and 6 are jacked up simultaneously by the respective jacks 13 so that the adjacent edge portions of the main girders 4 and 5 and the main girders 5 and 6 are connected to each other. In each end horizontal girder 8a, 8b connected, and each girder bracket 9a, 9b, 9c existing on each bridge axial direction surface of the cross beam 3 of the steel pier 1 and each support 10 above it, Since the load from each of the main girders 4, 5 and 6 is not applied, the existing girder brackets 9a, 9b and 9c and the existing supports 10 are removed from the transverse beam 3 in this state.

その後、上記中主桁５の切欠き部７の周りに設けてあった下フランジを切除してから、図３９（ロ）に示すように、中主桁５の桁端の残存するウェブに、所要形状のフルウェブ化補強部材１４をボルト接合して、中主桁５の桁端をフルウェブ化する。更に、上記フルウェブ化された中主桁５の桁端における上記増設横梁１１の上方で且つ後述する新規支承１６の上方に配される位置には、支点上補剛材１５をウェブ両側面と下フランジにリブ状に取り付けて補強しておくようにする。 Then, after cutting out the lower flange provided around the notch 7 of the middle main girder 5, as shown in FIG. 39 (B), the remaining web at the end of the middle main girder 5, A full-web reinforcing member 14 having a required shape is bolted to form a full web at the end of the middle main beam 5. Further, the stiffeners 15 on the fulcrum are placed on both side surfaces of the web at the position of the full web-formed middle main girder 5 above the additional lateral beam 11 and above the new support 16 described later. Attach to the lower flange in a rib shape and reinforce it.

又、同様に、図３９（ハ）に示すように、上記各外主桁４，６の桁端における上記増設横梁１１の上方で且つ後述する新規支承１６の上方に配される位置にも、支点上補剛材１５をウェブ両側面と下フランジにリブ状に取り付けて補強しておくようにする。 Similarly, as shown in FIG. 39 (c), at the positions of the outer main girders 4 and 6 above the additional horizontal beam 11 and above the new support 16 to be described later, The fulcrum upper stiffener 15 is attached to both sides of the web and the lower flange in a rib shape to be reinforced.

上記のようにして中主桁５の桁端のフルウェブ化が終了した後は、図３９（イ）（ロ）（ハ）に示すように、上記増設横梁１１における各主桁４，５，６の桁端の下方となる位置に、新規支承１６をそれぞれ設置してから、上記各ジャッキ１３をジャッキダウンすることにより、上記各主桁４，５，６の桁端を、上記各新規支承１６を介して上記増設横梁１１に支持させるようにして、支承の取り替えと支承周りの補強の工事を終了する。 After completing the full web at the end of the middle main beam 5 as described above, as shown in FIGS. 39 (a), (b) and (c), the main beams 4, 5, After the new bearings 16 are installed at positions below the end of the six girders, the jacks 13 are jacked down so that the main girders 4, 5, 6 are connected to the new girders. The support is replaced and the reinforcement work around the support is completed by supporting the additional lateral beam 11 via 16.

しかる後、上記各ジャッキ１３及びジャッキアップ用受台１２ａ，１２ｂ，１２ｃをそれぞれ撤去するようにしてある。 Thereafter, each of the jacks 13 and the jack-up receiving bases 12a, 12b, and 12c are removed.

なお、上記増設横梁１１の各ジャッキアップ用受台１２ａ，１２ｂ，１２ｃ上に設置した各ジャッキ１３によりすべての主桁４，５，６を同時にジャッキアップさせる工程の後は、上記既設の各端横桁８ａ，８ｂに上記各主桁４，５，６からの荷重が作用しなくなる。このため、該各端横桁８ａ，８ｂは、上記すべての主桁４，５，６の同時ジャッキアップ工程の後で、必要に応じて取り替え等を行うようにしてある。 In addition, after the step of jacking up all the main girders 4, 5 and 6 simultaneously with the jacks 13 installed on the jack-up receiving bases 12a, 12b, and 12c of the additional lateral beam 11, the existing ends Loads from the main girders 4, 5 and 6 do not act on the horizontal girders 8a and 8b. For this reason, the end cross girders 8a and 8b are replaced as necessary after the simultaneous jack-up process of all the main girders 4, 5 and 6.

下里哲弘，「首都高速道路の若返り作戦」，ＪＳＳＣ会誌，社団法人日本鋼構造協会，２００３年１０月，Ｎｏ.５０，ｐ.１−１０Tetsuhiro Shimozato, “Operation Rejuvenation of Metropolitan Expressway”, JSSC Journal, Japan Steel Structure Association, October 2003, No. 50, p. 1-10

ところが、従来行われている主桁フルウェブ化工事では、鋼製橋脚１の既設の横梁３の下側に、ジャッキアップ用受台１２ａ，１２ｂ，１２ｃを具備した増設横梁１１を設けて、上記各ジャッキアップ用受台１２ａ，１２ｂ，１２ｃ上にそれぞれ設置したジャッキ１３により上記すべての主桁４，５，６を同時にジャッキアップすることで、隣接する主桁４と５及び主桁５と６の桁端縁部同士を接続している既設の各端横桁８ａ，８ｂ、及び、既設の各桁受ブラケット９ａ，９ｂ，９ｃ、及び、既設の各支承１０に上記各主桁４，５，６より作用している荷重を一度に抜くことができるため、上記すべての主桁４，５，６の同時ジャッキアップ工程の後で、上記既設の各端横桁８ａ，８ｂの取り替えや、各桁受ブラケット９ａ，９ｂ，９ｃ及び各支承１０の撤去や取り替えを行うことが可能となるが、該主桁フルウェブ化工事では、上記増設横梁１１を、元々フルウェブとしてある各外主桁４，６の桁端と、新たにフルウェブ化する中主桁５の桁端を新規支承１６を介して下方から受けることができるよう鋼製橋脚１の既設の横梁３の下側に設ける必要があるため、建築限界により上記既設の横梁３の下側の空間が制限されていて、上記増設横梁１１を取り付けるための上下方向のスペースが確保できないＩ桁橋に対しては適用することができない。 However, in the conventional main girder full web construction, an additional lateral beam 11 provided with jack-up cradles 12a, 12b, 12c is provided below the existing lateral beam 3 of the steel pier 1, By jacking up all the main girders 4, 5 and 6 at the same time with the jacks 13 respectively installed on the jacking bases 12a, 12b and 12c, the adjacent main girders 4 and 5 and the main girders 5 and 6 The existing girder edges 8a and 8b connecting the edge edges of the girder, and the existing girder brackets 9a, 9b, and 9c, and the existing support 10 to the main girder 4 and 5 , 6 can be removed at a time, so that after the simultaneous jack-up process of all the main girders 4, 5 and 6, the existing end cross girders 8a and 8b can be replaced, Each girder bracket 9a, 9b, 9c and Each support 10 can be removed or replaced. However, in the main girder full web construction, the above-mentioned expanded cross beam 11 is newly connected to the girder ends of the outer main girder 4 and 6 that are originally full webs. Since it is necessary to provide the underside of the existing cross beam 3 of the steel pier 1 so that the end of the middle main girder 5 to be full web can be received from below through the new support 16, the above-mentioned existing It cannot be applied to an I-girder bridge in which the space below the horizontal beam 3 is limited and a vertical space for mounting the additional horizontal beam 11 cannot be secured.

そのために、上記したように鋼製橋脚１の既設の横梁３の下側に増設横梁１１を取り付けるための上下方向のスペースが確保できないＩ桁橋においては、支承１０及び支承周りの補修や補強を行う手順上、上記既設の各端横桁８ａ，８ｂの取り替えが望まれる場合であっても、上記既設の各端横桁８ａ，８ｂより、各支承１０と既設の各桁受ブラケット９ａ，９ｂ，９ｃを介して各主桁４，５，６の荷重を上記横梁３へ伝える荷重伝達経路に作用している荷重を抜くための手法が特に提案されていないため、上記既設の各端横桁８ａ，８ｂを取り替える工事は従来行われていないというのが実状である。 Therefore, as described above, in the I-girder bridge where the vertical space for attaching the additional lateral beam 11 to the lower side of the existing lateral beam 3 of the steel pier 1 cannot be secured, repair and reinforcement around the bearing 10 and the bearing are performed. Even if it is desired to replace the existing end cross beams 8a and 8b in the procedure to be performed, the support 10 and the existing girder brackets 9a and 9b are installed from the existing end cross beams 8a and 8b. , 9c, a method for removing the load acting on the load transmission path for transmitting the loads of the main girders 4, 5, 6 to the cross beam 3 is not particularly proposed. The actual situation is that construction for replacing 8a and 8b has not been performed in the past.

そこで、本発明は、桁橋における各主桁の桁端縁部同士を連結し且つ上記各主桁からの荷重を支承を介して橋脚側の桁受ブラケットへ伝えて支持させるようにしてある既設の横桁を、新たな横桁に取り替えることができ、更には、支承の取り替えによる機能回復や、支承周りの補強を図ることができるようにするための横桁取替方法を提供しようとするものである。 Therefore, the present invention connects existing girder edges of each main girder in the girder bridge and transmits the load from each main girder to the girder bracket on the pier side via the support for support. It is intended to provide a cross-girder replacement method that can replace the cross-beam with a new cross-girder, and further restore the function by replacing the bearing and reinforce the area around the bearing. Is.

本発明は、上記課題を解決するために、請求項１に対応して、橋幅方向両端部に位置する各外主桁と橋幅方向の内側に位置する中主桁とを、橋脚の横梁と平行に橋幅方向に延びる別々の支承用の横桁で接続し、且つ上記橋脚の横梁の橋軸方向の側面に突設した桁受ブラケットに、上記中主桁の桁端と、上記各支承用の横桁の橋幅方向外側端部寄り個所を、それぞれ支承を介して支持させてなる桁橋における上記各外主桁をジャッキアップすると共に、上記各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップした状態で、上記各支承用の横桁のうちの他方の外主桁側の横桁を、新しい横桁に取り替え、次いで、上記各外主桁をジャッキアップした状態で、上記取り替えられた他方の新設の横桁をジャッキアップし、上記支承用の一方の外主桁側の横桁をジャッキダウンしてから、該ジャッキダウンした一方の横桁を新しい横桁に取り替えるようにする。 In order to solve the above-mentioned problem, the present invention corresponds to claim 1 and includes each outer main girder located at both ends in the bridge width direction and middle main girder located inside in the bridge width direction. The girder brackets connected to the horizontal beams for separate supports extending in the width direction of the bridge in parallel to the bridge and projecting on the side surfaces in the bridge axis direction of the horizontal beams of the bridge piers, Jack up each outer main girder in the girder bridge that supports the outer girder bridge end in the width direction of the supporting girder via the support, and one of the girder for each supporting With the horizontal girder on the outer main girder side being jacked up, replace the other girder on the other outer main girder side with a new cross girder, and then replace each outer main girder In the jacked-up state, jack up the other newly installed horizontal girder and replace the one for the above-mentioned support. Of the crossbeam of the outer main beam side from the jack down, so replace transverses whereas the said jack down new crossbeam.

又、上記構成において、各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、各支承用の横桁の橋幅方向外側端部寄り個所の支持に用いられていた各桁受ブラケットを撤去するようにし、更に、支承用の他方及び一方の横桁が新設の横桁に取り替えられた状態で、各外主桁の桁端を、該各外主桁の桁端直下位置にそれぞれ新設した各ブラケットに新規支承を介して載置すると共に、中主桁の桁端を、対応する桁受ブラケット上にて既設の支承に取り替えて設けた新規支承を介して載置するようにする。 Also, in the above configuration, each outer main girder is jacked up, and when the horizontal girder on one outer main girder side of each support is jacked up, or each outer main girder is jacked up In the state, when the other newly installed cross beam is jacked up, among the girder brackets protruding from the cross beam of the bridge pier, the position near the outer edge of the bridge width direction of the cross beam for each support Each girder bracket used to support the outer girder is removed, and the end of each outer main girder is attached to the other main girder with the other and one cross girder being replaced with new ones. It was placed on each newly installed bracket directly under the end of each outer main girder via a new support, and the end of the middle main girder was replaced with the existing support on the corresponding girder bracket. Place it through a new bearing.

更に、上記構成において、各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、中主桁の桁端の支持に用いられていた既設の桁受ブラケットを、新たな桁受ブラケットに取り替えて、中主桁の桁端を、上記取り替えた新設の桁受ブラケット上に新規支承を介して載置するようにする。 Furthermore, in the above configuration, each outer main girder is jacked up, and when the horizontal girder on one outer main girder side of each support is jacked up, or each outer main girder is jacked up. In the state, when the other newly installed horizontal girder was jacked up, the existing girder bracket used to support the girder end of the middle main girder among the girder brackets protruding from the cross beam of the pier The girder bracket is replaced with a new girder bracket, and the end of the middle main girder is placed on the newly-replaced new girder bracket via the new support.

本発明の横桁取替方法によれば、以下のような優れた効果を発揮する。
（１）橋幅方向両端部に位置する各外主桁と橋幅方向の内側に位置する中主桁とを、橋脚の横梁と平行に橋幅方向に延びる別々の支承用の横桁で接続し、且つ上記橋脚の横梁の橋軸方向の側面に突設した桁受ブラケットに、上記中主桁の桁端と、上記各支承用の横桁の橋幅方向外側端部寄り個所を、それぞれ支承を介して支持させてなる桁橋における上記各外主桁をジャッキアップすると共に、上記各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップした状態で、上記各支承用の横桁のうちの他方の外主桁側の横桁を、新しい横桁に取り替え、次いで、上記各外主桁をジャッキアップした状態で、上記取り替えられた他方の新設の横桁をジャッキアップし、上記支承用の一方の外主桁側の横桁をジャッキダウンしてから、該ジャッキダウンした一方の横桁を新しい横桁に取り替えるようにしてあるので、上記各支承用の横桁を順次取り替えることができ、よって、橋脚の横梁の下側に増設横梁を取り付けるための上下方向のスペースが確保できないために主桁フルウェブ化工事を適用できない桁橋においても、上記各支承用の横桁の新設の横桁への取替作業を確実に実施することができる。
（２）各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、各支承用の横桁の橋幅方向外側端部寄り個所の支持に用いられていた各桁受ブラケットを撤去するようにし、更に、支承用の他方及び一方の横桁が新設の横桁に取り替えられた状態で、各外主桁の桁端を、該各外主桁の桁端直下位置にそれぞれ新設した各ブラケットに新規支承を介して載置すると共に、中主桁の桁端を、対応する桁受ブラケット上にて既設の支承に取り替えて設けた新規支承を介して載置するようにすることにより、各主桁の荷重を支持するための支承をすべて新規支承へ取り替えることができて、支承の機能回復を図ることができると共に、支承周りの補強を行うことが可能になる。
（３）各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、中主桁の桁端の支持に用いられていた既設の桁受ブラケットを、新たな桁受ブラケットに取り替えて、中主桁の桁端を、上記取り替えた新設の桁受ブラケット上に新規支承を介して載置するようにすることにより、中主桁の桁端を、新規桁受ブラケットに支持させることで、該中主桁を支持する支承回りの補強を実施することができる。 According to the cross beam replacement method of the present invention, the following excellent effects are exhibited.
(1) Connect each outer main girder located at both ends of the bridge width direction and middle main girder located inside the bridge width direction with separate support cross beams that extend in the bridge width direction in parallel with the cross beam of the bridge pier. And, on the girder bracket projecting on the side surface in the bridge axis direction of the cross beam of the pier, the girder end of the middle main girder and the position near the outer end in the bridge width direction of the horizontal girder for each support, While jacking up each outer main girder in a girder bridge supported via a support and jacking up one outer main girder side of the above-mentioned horizontal girder for each support, Replace the cross beam on the other outer main girder side of the support cross beam with a new cross beam, and then, with the outer main girders jacked up, replace the other newly installed cross beam Jack up, jack down the horizontal girder on one outer main girder side for support, and then Since one of the crossed girder is replaced with a new girder, it is possible to sequentially replace the girder for each of the above-mentioned supports. Even in a girder bridge where the main girder full web construction work cannot be applied because space cannot be secured, the above-described work for replacing the horizontal girder for each support can be reliably performed.
(2) While jacking up each outer main girder and jacking up one outer main girder's horizontal girder, or with each outer main girder jacked up, When jacking up the other newly installed cross girder, the support brackets of the girder brackets protruding from the cross beam of the bridge pier are supported near the outer edge of the bridge in the bridge width direction. Each girder bracket used was removed, and the end of each outer main girder was connected to the outer main girder with the other and one side girder for the support replaced with new ones. A new support is installed on each newly installed bracket directly below the end of the girder via a new support, and the end of the middle main girder is replaced with the existing support on the corresponding girder bracket. To support the load of each main girder All because bearing of can be replaced to a new bearing, it is possible to achieve functional recovery of the bearing, it is possible to perform the reinforcement around the bearing.
(3) Jacking up each outer main girder and jacking up one outer main girder's horizontal girder, or in a state where each outer main girder is jacked up, The existing girder bracket used to support the end of the middle main girder among the girder brackets protruding from the cross beam of the pier when the other newly installed girder is jacked up Is replaced with a new girder bracket, and the end of the middle main girder is placed on the newly-replaced girder bracket with the new support. By supporting the new girder bracket, it is possible to reinforce the bearing support that supports the middle main girder.

本発明の横桁取替方法の実施の一形態を示す手順のフロー図である。It is a flowchart of the procedure which shows one Embodiment of the cross beam replacement method of this invention. 図１の方法のステップＡ１ａで各外主桁の桁端に切欠き部を設け、ステップＡ１ｂで横梁に外主桁ジャッキアップ用受台を設け、ステップＡ２で横梁に第１の端横桁ジャッキアップ用受台を設けた状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＡ−Ａ方向矢視図、（ハ）は（イ）のＢ−Ｂ方向矢視図である。In step A1a of the method of FIG. 1, a notch is provided at the end of each outer main girder, in step A1b, the outer main girder jack-up support is provided in the cross beam, and in step A2, the first end cross girder jack is provided in the cross beam. It shows a state in which a cradle for up is provided, (a) is a schematic plan view, (b) is a view taken in the direction of arrows AA in (b), and (c) is a arrow in directions B-B of (b). FIG. 図１の方法のステップＡ３で各外主桁及び既設の一方の端横桁をジャッキアップした状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＣ−Ｃ方向矢視図である。1 shows a state in which each outer main girder and one existing end cross girder are jacked up in step A3 of the method of FIG. 1, (A) is a schematic plan view, and (B) is a CC direction of (A). It is an arrow view. 図１の方法にて、図３のジャッキアップの後の手順を示すもので、（イ）はステップＡ４で既設の他方の端横桁を撤去した状態を、（ロ）はステップＡ５で新設の他方の端横桁を取り付けた状態をそれぞれ示す図３（ロ）に対応する図である。FIG. 3 shows the procedure after jack-up in FIG. 3 by the method of FIG. 1, in which (a) shows the state in which the other end cross girder is removed at step A4, and (b) shows the newly installed step at step A5. It is a figure corresponding to Drawing 3 (b) which shows the state where the other end cross beam was attached, respectively. 図１の方法のステップＡ６で第２の端横桁ジャッキアップ用受台を設けた状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＤ−Ｄ方向矢視図である。FIG. 2 shows a state in which a second end cross girder jack-up cradle is provided in step A6 of the method of FIG. 1, (A) is a schematic plan view, and (B) is a view in the DD direction of (A). FIG. 図１の方法にて、図５の後の手順を示すもので、（イ）はステップＡ７で第１の端横桁ジャッキアップ用受台上のジャッキより第２の端横桁ジャッキアップ用受台上のジャッキに荷重を受替えた状態を、（ロ）はステップＡ８で既設の一方の端横桁を撤去した状態を、（ハ）はステップＡ９で新設の一方の端横桁を取り付けた状態を、それぞれ示す図５（ロ）に対応する図である。FIG. 5 shows the procedure after FIG. 5 in the method of FIG. 1, in which (a) shows a step for receiving a second end cross-girder jack-up receiving jack from a jack on the first end cross-girder jack-up receiving base. The state in which the load is transferred to the jack on the table, (B) is the state in which the existing one end cross beam is removed in Step A8, and (C) is the one end cross beam installed in Step A9. It is a figure corresponding to Drawing 5 (b) which shows a state, respectively. 図１の方法のステップＡ１０で各外主桁と新設の他方の端横桁をジャッキアップしていた各ジャッキをジャッキダウンする状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＥ−Ｅ方向矢視図である。1 shows a state in which each outer main girder and each jack that has been jacked up at the other end horizontal girder in step A10 of the method of FIG. 1 are jacked down, (A) is a schematic plan view, (B) is It is an EE direction arrow directional view of (a). 図１の方法のステップＡ１ａで外主桁に切欠き部を設ける場合の補強手順を示すもので、（イ）は外主桁の橋幅方向外側面に外主桁外側補強部材を取り付ける状態を、（ロ）は、外主桁の橋幅方向内側面の既設補剛材を撤去した状態をそれぞれ示す概略斜視図である。1 shows a reinforcing procedure when a notch is provided in the outer main girder in step A1a of the method of FIG. 1, wherein (a) shows a state in which the outer main girder outer reinforcing member is attached to the outer side surface of the outer main girder in the bridge width direction. (B) is a schematic perspective view showing a state where the existing stiffeners on the inner side surface in the bridge width direction of the outer main girder are removed. 図１の方法のステップＡ１ａで外主桁に切欠き部を設ける場合の補強手順における図８（ロ）の後の手順を示すもので、（イ）は外主桁の橋幅方向内側面に外主桁内側補強材を取り付ける状態を、（ロ）は外主桁の桁端に切欠きを設けた状態をそれぞれ示す概略斜視図である。FIG. 9 shows the procedure after FIG. 8 (b) in the reinforcing procedure when the outer main girder is provided with a notch in step A1a of the method of FIG. 1, wherein (a) is on the inner surface of the outer main girder in the bridge width direction. (B) is a schematic perspective view showing a state in which a notch is provided at the end of the outer main girder. 図１の方法のステップＡ１ａで外主桁に切欠き部を設ける場合の補強手順における図９（ロ）の後の手順を示すもので、各外主桁に外主桁内側桁端補強材を取り付ける状態を示す概略斜視図である。FIG. 9 shows the procedure after FIG. 9 (b) in the reinforcing procedure in the case where a cutout portion is provided in the outer main girder in step A1a of the method of FIG. 1, and the outer main girder inner girder edge reinforcing material is attached to each outer main girder. It is a schematic perspective view which shows the state to attach. 図１の方法で中主桁の桁端の補強を行う場合の手順を示すもので、（イ）は中主桁の橋幅方向一側面の既設補剛材を撤去した状態を、（ロ）は中主桁の橋幅方向一側面に中主桁補強材を取り付ける状態をそれぞれ示す概略斜視図である。Fig. 1 shows the procedure for reinforcing the beam end of the middle main girder by the method of Fig. 1. (b) shows the state where the existing stiffener on one side of the bridge width direction of the middle main girder has been removed. These are the schematic perspective views which respectively show the state which attaches a middle main girder reinforcing material to the bridge width direction one side surface of a middle main girder. 図１の方法で中主桁の桁端の補強を行う場合の手順における図１１（ロ）の後の手順を示すもので、（イ）は中主桁の橋幅方向他端面の既設補剛材を撤去した状態を、（ロ）は中主桁の橋幅方向他側面に中主桁補強材を取り付ける状態をそれぞれ示す概略斜視図である。FIG. 11B shows the procedure after FIG. 11B in the procedure for reinforcing the beam end of the middle main girder by the method of FIG. 1, and FIG. (B) is a schematic perspective view which shows the state which attaches a middle main girder reinforcing material to the bridge width direction other side surface of a middle main girder, respectively. 図１の方法で中主桁の桁端の補強を行う場合の手順における図１２（ロ）の後の手順を示すもので、中主桁の橋幅方向の各側面に中主桁桁端補強材をそれぞれ取り付ける状態を示す概略斜視図である。FIG. 12 shows the procedure after FIG. 12 (b) in the procedure for reinforcing the end of the middle main girder by the method of FIG. 1, and reinforces the middle main girder end on each side in the bridge width direction of the middle main girder. It is a schematic perspective view which shows the state which each attaches material. 図１の方法で中主桁の桁端の補強を行う場合の手順における図１３の後の手順を示すもので、中主桁の桁端の既設の切欠き部の周りのウェブを切断して新たな切欠き部を形成した状態を示す概略側面図である。FIG. 14 shows the procedure after FIG. 13 in the procedure for reinforcing the end of the middle main girder by the method of FIG. 1 by cutting the web around the existing notch at the end of the middle main girder. It is a schematic side view which shows the state in which the new notch part was formed. 本発明の実施の他の形態として図１の方法の応用例を示す手順のフロー図である。It is a flowchart of the procedure which shows the application example of the method of FIG. 1 as another form of implementation of this invention. 図１５の方法にて、図４（イ）に示したと同様のステップＡ４の後に続いて行うステップＡ４ａで既設の他方の端横桁を支持していた桁受ブラケットと支承を撤去した状態を示す図４（イ）に対応する図である。FIG. 15 shows a state in which the girder bracket and the support that have supported the other end lateral girder in step A4a performed after step A4 similar to that shown in FIG. FIG. 5 is a diagram corresponding to FIG. 図１５の方法にて、図６（ロ）に示したと同様のステップＡ８の後に続いて行うステップＡ８ａで既設の一方の端横桁を支持していた桁受ブラケットと支承を撤去した状態を示す図６（ロ）に対応する図である。FIG. 15 shows a state in which the girder bracket and the support that have supported the one end lateral girder are removed in step A8a performed after step A8 similar to that shown in FIG. FIG. 7 is a diagram corresponding to FIG. 図１５の方法にて、図６（ハ）に示したと同様のステップＡ９の後の手順を示すもので、（イ）はステップＡ１２で各主桁の荷重を各端横桁ジャッキアップ用受台上のジャッキに受替えた状態を、（ロ）はステップＡ１３で各外主桁用の各外主桁ジャッキアップ用受台とその上のジャッキを撤去した状態を、それぞれ示す図６（ハ）に対応する図である。15 shows the procedure after step A9 similar to that shown in FIG. 6 (c) by the method of FIG. 15, wherein (a) shows the load of each main girder at each end cross-girder jack-up cradle in step A12. FIG. 6 (c) shows the state in which the jack has been replaced with the upper jack, and (b) shows the state in which the outer main girder jack-up cradle for each outer main girder and the upper jack are removed in step A13. It is a figure corresponding to. 図１５の方法のステップＡ１４で各外主桁の桁端直下に支点用ブラケットを設けた状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＦ−Ｆ方向矢視図、（ハ）は（イ）のＧ−Ｇ方向矢視図である。15 shows a state in which a fulcrum bracket is provided immediately below the end of each outer main girder in step A14 of the method of FIG. 15, wherein (a) is a schematic plan view, and (b) is a FF direction arrow of (a). FIG. 4C is a view taken along the arrow GG in FIG. 図１５の方法のステップＡ１５で各新設の端横桁をジャッキアップしていたジャッキをジャッキダウンする状態を示す図１９（ハ）に対応する図である。FIG. 20 is a view corresponding to FIG. 19 (c) showing a state in which a jack that has jacked up each newly installed end cross girder in step A 15 of the method of FIG. 15 is jacked down. 図１５の方法のステップＡ１６で各端横桁ジャッキアップ用受台とその上のジャッキを撤去した後の状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＨ−Ｈ方向矢視図、（ハ）は（イ）のＩ−Ｉ方向矢視図である。FIG. 16 shows the state after the cradle for each end cross-girder jack-up and the jack on it are removed in step A16 of the method of FIG. 15, wherein (a) is a schematic plan view, and (b) is H of (b). -H direction arrow view, (c) is the II direction arrow view of (a). 本発明の実施の更に他の形態を示す手順のフロー図である。It is a flowchart of the procedure which shows other form of implementation of this invention. 図２２の方法のステップＢ１で外主桁の桁端に切欠き部を設け、ステップＢ２で横梁に新規桁受ブラケットを設け、ステップＢ３で横梁に端横桁ジャッキアップ用受台を設け、ステップＢ４でアウトリガーと仮設横桁を設け、ステップＢ５で横梁にジャッキアップ用受台を設けた状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＪ−Ｊ方向矢視図、（ハ）は（イ）のＫ−Ｋ方向矢視図である。In step B1 of the method of FIG. 22, a notch is provided at the end of the outer main girder, a new girder bracket is provided on the cross beam in step B2, and an end cross girder jack-up cradle is provided on the cross beam in step B3. B4 shows an outrigger and a temporary horizontal girder, and step B5 shows a state where a jack-up cradle is provided on the cross beam. (A) is a schematic plan view, (b) is a JJ direction arrow of (a). FIG. 5C is a view taken in the direction of arrows KK in FIG. 図２２の方法のステップＢ６で各アウトリガーと既設の一方の端横桁をジャッキアップした状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＬ−Ｌ方向矢視図である。22 shows a state in which each outrigger and the existing one end cross girder are jacked up in step B6 of the method of FIG. 22, wherein (A) is a schematic plan view, and (B) is a view in the LL direction of (A). FIG. 図２２の方法における図２４のジャッキアップの後の手順を示すもので、（イ）はステップＢ７で既設の橋幅方向両側の桁受ブラケットと支承を撤去した状態を、（ロ）はステップＢ８で既設の他方の端横桁を撤去した状態を、（ハ）はステップＢ９で新設の他方の端横桁を取り付けた状態を、それぞれ示す図２４（ロ）に対応する図である。22 shows the procedure after the jack-up of FIG. 24 in the method of FIG. 22, wherein (a) shows a state where the existing girder brackets and supports on both sides in the bridge width direction are removed in step B7, and (b) shows step B8. FIG. 25C is a view corresponding to FIG. 24 (B) showing the state in which the existing other end cross beam is removed, and (C) shows the state in which the other end end cross beam is attached in step B9. 図２２の方法における図２５（ハ）の後の手順を示すもので、（イ）はステップＢ１０で第１の端横桁ジャッキアップ用受台上のジャッキより第２の端横桁ジャッキアップ用受台上のジャッキに荷重を受替えた状態を、（ロ）はステップＢ１１で既設の一方の端横桁を受けていたジャッキを撤去した状態をそれぞれ示す図２４（ロ）に対応する図である。FIG. 25 shows the procedure after FIG. 25 (c) in the method of FIG. 22, wherein (b) shows a step for jacking up the second end cross girder from the jack on the first end cross girder jack up cradle in step B10. FIG. 24B is a view corresponding to FIG. 24B, which shows a state in which the load is transferred to the jack on the cradle, and FIG. 24B shows a state in which the jack that has received the one end cross girder is removed in step B11. is there. 図２２の方法における図２６（ロ）の後の手順を示すもので、（イ）はステップＢ１２で既設の一方の端横桁を撤去した状態を、（ロ）はステップＢ１３で新設の一方の端横桁を取り付けた状態をそれぞれ示す図２４（ロ）に対応する図である。FIG. 26 shows the procedure after FIG. 26 (b) in the method of FIG. 22, (a) shows the state where one of the existing end beams is removed in step B12, and (b) shows one of the newly installed steps in step B13. It is a figure corresponding to FIG. 24 (b) which each shows the state which attached the end cross beam. 図２２の方法のステップＢ１４で中主桁に対応する桁受ブラケット上の既設の支承を撤去し、該桁受ブラケットを補強した状態を示す概略切断側面図である。FIG. 23 is a schematic cut-away side view showing a state in which the existing support on the girder bracket corresponding to the middle main girder is removed and the girder bracket is reinforced in step B14 of the method of FIG. 図２２の方法のステップＢ１５で新たな支承を設けてから各アウトリガーと新設の他方の端横桁をジャッキダウンする状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＭ−Ｍ方向矢視図である。22 shows a state in which each outrigger and the newly installed other end cross girder are jacked down after providing a new support in step B15 of the method of FIG. 22, wherein (a) is a schematic plan view, and (b) is (b). It is a MM direction arrow directional view. 図２２の方法のステップＢ１６で端横桁ジャッキアップ用受台、アウトリガー、仮設横桁、ジャッキを撤去した後の状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＮ−Ｎ方向矢視図、（ハ）は（イ）のＯ−Ｏ方向矢視図である。22 shows the state after removing the end cross girder jack-up cradle, the outrigger, the temporary cross girder, and the jack in step B16 of the method of FIG. 22, (A) is a schematic plan view, and (B) is (B). NN direction arrow view of (a), (c) is an OO direction arrow view of (a). 本発明の実施の更に他の形態を示す手順のフロー図である。It is a flowchart of the procedure which shows other form of implementation of this invention. 図３１の方法にて、図２７（ロ）に示したと同様のステップＢ１３の後の手順を示すもので、（イ）はステップＢ１７で既設の中主桁支持用の桁受ブラケットを撤去した状態を、（ロ）はステップＢ１８で中主桁支持用の新規桁受ブラケットを設けた状態を、それぞれ示す図２７（ロ）に対応する図である。31 shows the procedure after step B13 similar to that shown in FIG. 27 (b) by the method shown in FIG. 31, wherein (b) shows the state in which the existing girder bracket for supporting the middle main girder is removed in step B17. (B) is a view corresponding to FIG. 27 (b) showing the state in which the new girder bracket for supporting the middle main girder is provided in step B18. 図３１の方法にてステップＢ１９で新たな支承を設けてから各アウトリガーと新設の他方の端横桁をジャッキダウンする状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＰ−Ｐ方向矢視図である。FIG. 31 shows a state in which a new support is provided in step B19 by the method shown in FIG. 31, and then each outrigger and the newly installed other end cross beam are jacked down. (A) is a schematic plan view and (B) is (I). It is a PP direction arrow directional view. 図３１の方法のステップＢ２０でアウトリガー、仮設横桁、ジャッキを撤去した後の状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＱ−Ｑ方向矢視図である。FIG. 31 shows a state after the outrigger, temporary cross beam, and jack are removed in step B20 of the method of FIG. 31, (A) is a schematic plan view, and (B) is a QQ direction arrow view of (A). is there. 従来首都高速道路等で用いられている３主Ｉ桁橋の一例の概略を示すもので、（イ）は概略平面図、（ロ）は（イ）のＲ−Ｒ方向矢視図、（ハ）は（イ）のＳ−Ｓ方向矢視図である。An outline of an example of the three main I girder bridges conventionally used on the Metropolitan Expressway, etc. is shown. (A) is a schematic plan view, (B) is a view taken in the direction of arrows RR in (A), (C ) Is a view taken in the direction of the arrow S-S in (a). 図３５の３主Ｉ桁橋における主桁の支持構造部分を拡大して示す斜視図である。It is a perspective view which expands and shows the support structure part of the main girder in 3 main I girder bridges of FIG. 従来行われている主桁フルウェブ化工事にて鋼製橋脚の横梁の下方に増設横梁を設けた状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＴ−Ｔ方向矢視図である。This figure shows a state where an additional horizontal beam is installed under the horizontal beam of the steel pier in the conventional main girder full web construction, where (a) is a schematic plan view and (b) is a T- It is a T direction arrow view. 主桁フルウェブ化工事にて各主桁をジャッキアップした状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＵ−Ｕ方向矢視図、（ハ）は（イ）のＶ−Ｖ方向矢視図である。It shows the state where each main girder is jacked up in the main girder full web construction. (A) is a schematic plan view, (b) is a view taken in the direction of the U-U arrow in (a), (c) is ( It is a VV direction arrow line view of a). 主桁フルウェブ化工事にて中主桁をフルウェブ化した後、新規支承の上側に各主桁を載置した状態を示すもので、（イ）は概略平面図、（ロ）は（イ）のＷ−Ｗ方向矢視図、（ハ）は（イ）のＸ−Ｘ方向矢視図である。This figure shows the state where each main girder is placed on the upper side of the new bearing after the main main girder is converted into a full web in the main girder full web construction. (B) is a schematic plan view, (b) is (b) ) Is a view in the WW direction, and (c) is a view in the direction XX of (a).

以下、本発明を実施するための形態を図面を参照して説明する。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

図１乃至図１４は本発明の横桁取替方法の実施の一形態を示すもので、図１にフローを示す如き手順としてある。 FIG. 1 to FIG. 14 show an embodiment of the cross beam replacement method of the present invention, and the procedure is as shown in FIG.

すなわち、図３５（イ）（ロ）（ハ）及び図３６に示したと同様に、桁端がフルウェブの外主桁４，６と、桁端に切欠き部７を有する中主桁５とを備え、且つ隣接する主桁４と５及び主桁５と６の桁端縁部同士を橋幅方向の端横桁８ａ，８ｂで接続して、鋼製橋脚１の横梁３における橋軸方向面に突設した桁受ブラケット９ａ，９ｂ，９ｃに、上記中主桁５の切欠き部７の上側の桁端、及び、上記各端横桁８ａ，８ｂの橋幅方向外側端部寄り個所を、支承１０を介してそれぞれ支持させるようにしてなる構成のＩ桁橋における上記各外主桁４，６の桁端の直下に、図２（イ）（ロ）に示す如く、外主桁ジャッキアップ用受台１７を設置する（ステップＡ１：ＳＡ１）。 That is, as shown in FIGS. 35 (A), (B), (C) and FIG. 36, the outer main girders 4 and 6 with full webs at the end of the web and the middle main girders 5 having the notches 7 at the end of the girders. And the adjacent main girders 4 and 5 and the end edges of the main girders 5 and 6 are connected to each other by end cross girders 8a and 8b in the bridge width direction, and the direction of the bridge axis in the cross beam 3 of the steel pier 1 Girder brackets 9a, 9b, and 9c projecting from the surface are located on the upper girder end of the notch portion 7 of the middle main girder 5 and the outer end portions in the bridge width direction of the end transverse girders 8a and 8b. As shown in FIGS. 2 (a) and 2 (b) immediately below the end of each of the outer main girders 4 and 6 in the I-girder bridge constructed so as to be supported by the support 10 respectively. A jack-up cradle 17 is installed (step A1: SA1).

上記ステップＡ１（ＳＡ１）は、具体的には、先ず、上記各外主桁４，６の桁端下部に切欠き部１８をそれぞれ設け（ステップＡ１ａ：ＳＡ１ａ）、上記鋼製橋脚１の横梁３の各橋軸方向面における上記各外主桁４，６とそれぞれ対応する橋幅方向の所要個所の下部位置に、上記各主桁４，６の桁端に設けた切欠き部１８の内側で橋軸方向に突出する外主桁ジャッキアップ用受台１７を設けるようにする（ステップＡ１ｂ：ＳＡ１ｂ）。 Specifically, in step A1 (SA1), first, notch portions 18 are respectively provided at the lower ends of the outer main girders 4 and 6 (step A1a: SA1a), and the cross beam 3 of the steel pier 1 is provided. At the lower position of the required portion in the bridge width direction corresponding to each of the outer main girders 4 and 6 on each bridge axial direction surface, inside the notch portion 18 provided at the end of each of the main girders 4 and 6. An outer main girder jack-up receiving base 17 projecting in the bridge axis direction is provided (step A1b: SA1b).

又、図２（イ）（ハ）に示す如く、上記横梁３の各橋軸方向面における上記既設の各端横桁８ａ，８ｂのうちのいずれか片方、たとえば、一方の外主桁４と中主桁５の桁端縁部同士を接続している端横桁８ａの橋幅方向内側端部寄りと対応する個所の下部位置に、第１の端横桁ジャッキアップ用受台１９ａを、上記一方の端横桁８ａの下方位置まで突出させて設ける（ステップＡ２：ＳＡ２）。 Further, as shown in FIGS. 2 (a) and 2 (c), one of the existing end cross beams 8a and 8b on each bridge axial direction surface of the cross beam 3, for example, one outer main beam 4 and At the lower position of the portion corresponding to the inner width of the end cross girder 8a connecting the end portions of the middle main girder 5 to each other in the bridge width direction, a first end cross girder jack-up cradle 19a, It is provided so as to project to a position below the one end cross beam 8a (step A2: SA2).

次に、図３（イ）（ロ）に示すように、上記各外主桁ジャッキアップ用受台１７の上にジャッキ２０ａ，２０ｂを、又、上記第１の端横桁ジャッキアップ用受台１９ａの上にジャッキ２０ｃをそれぞれ設置して、該各ジャッキ２０ａ，２０ｂ，２０ｃにより、それぞれの上方に位置している各外主桁４，６及び上記一方の端横桁８ａを同時にジャッキアップさせる（ステップＡ３：ＳＡ３）。これにより、上記各主桁４，５，６の荷重は、上記各外主桁４，６の桁端より各ジャッキ２０ａ，２０ｂと各外主桁ジャッキアップ用受台１７を介して、又、上記一方の端横桁８ａよりジャッキ２０ｃと第１の端横桁ジャッキアップ用受台１９ａを介して、それぞれ上記鋼製橋脚１の横梁３に伝えられて支持されるようになる。よって、上記既設の各端横桁８ａ，８ｂのうち、他方の端横桁８ｂには、上記各主桁４，５，６の荷重が作用しなくなるため、この状態で、図４（イ）に示すように、上記他方の端横桁８ｂの長手方向両端部を、中主桁５と他方の外主桁６よりそれぞれ切り離すことで撤去する（ステップ４Ａ：ＳＡ４）。 Next, as shown in FIGS. 3A and 3B, jacks 20a and 20b are placed on the outer main girder jack-up cradle 17, and the first end cross-girder jack-up cradle. The jacks 20c are respectively installed on 19a, and the jacks 20a, 20b, and 20c are used to jack up the outer main girders 4 and 6 and the one end lateral girder 8a that are positioned above each at the same time. (Step A3: SA3). As a result, the load of each of the main girders 4, 5, 6 is transferred from the ends of the outer main girders 4, 6 via the jacks 20a, 20b and the outer main girder jack-up cradles 17, respectively. The one end cross beam 8a is transmitted to and supported by the cross beam 3 of the steel bridge pier 1 through the jack 20c and the first end cross beam jack-up cradle 19a. Therefore, among the existing end cross beams 8a and 8b, the load of the main beams 4, 5 and 6 does not act on the other end cross beam 8b. Therefore, in this state, FIG. As shown in FIG. 4, the longitudinal ends of the other end cross beam 8b are removed from the middle main beam 5 and the other outer main beam 6 respectively (step 4A: SA4).

次いで、上記中主桁５と他方の外主桁６の桁端縁部における上記既設の他方の端横桁８ｂの撤去部分に必要に応じて補強を行ってから、図４（ロ）に示すように、上記中主桁５と他方の外主桁６の各切欠き部７，１８の上側の桁端縁部同士の間に、橋幅方向に延びる新設の他方の端横桁２１ｂを一体に取り付ける（ステップＡ５：ＳＡ５）。 Next, the removed portion of the existing other end cross beam 8b at the end portion of the middle main girder 5 and the other outer main girder 6 is reinforced as necessary, and then shown in FIG. As described above, the newly installed other end girder 21b extending in the bridge width direction is integrally formed between the upper girder edges of the notch portions 7 and 18 of the middle main girder 5 and the other outer main girder 6. (Step A5: SA5).

上記のようにして既設の他方の端横桁８ｂが新設の他方の端横桁２１ｂに取り替えられた後は、図５（イ）（ロ）に示すように、上記横梁３の各橋軸方向面における上記新設の他方の端横桁２１ｂの橋幅方向内側端部寄りと対応する個所の下部位置に、第２の端横桁ジャッキアップ用受台１９ｂを、上記新設の他方の端横桁２１ｂの下方位置まで突出させて設ける（ステップＡ６：ＳＡ６）。 After the existing other end cross beam 8b is replaced with the new other end cross beam 21b as described above, as shown in FIGS. 5 (a) and 5 (b), the direction of each bridge axis of the cross beam 3 is as follows. A second end cross girder jack-up cradle 19b is installed at the lower position of the portion corresponding to the bridge width direction inner side end portion of the new other end cross girder 21b on the surface. It is provided so as to protrude to a position below 21b (step A6: SA6).

その後、図６（イ）に示すように、上記第２の端横桁ジャッキアップ用受台１９ｂの上に別のジャッキ２０ｄを設置して、該ジャッキ２０ｄにより上記新設の他方の端横桁２１ｂのジャッキアップを行う一方、上記既設の一方の端横桁８ａをジャッキアップしていた上記第１の端横桁ジャッキアップ用受台１９ａ上のジャッキ２０ｃをジャッキダウンする（ステップＡ７：ＳＡ７）。これにより、上記各主桁４，５，６の荷重が、上記各外主桁４，６より各ジャッキ２０ａ，２０ｂと各外主桁ジャッキアップ用受台１７を介して、又、上記既設の一方の端横桁８ａよりジャッキ２０ｃと第１の端横桁ジャッキアップ用受台１９ａを介してそれぞれ上記横梁３に伝えられて支持されていた状態から、該各主桁４，５，６の荷重が、上記各外主桁４，６より各ジャッキ２０ａ，２０ｂと各外主桁ジャッキアップ用受台１７を介して、又、上記新設の他方の端横桁２１ｂよりジャッキ２０ｄと第２の端横桁ジャッキアップ用受台１９ｂを介して、それぞれ上記横梁３に伝えられて支持される状態に受替えられるようになる。よって、上記既設の一方の端横桁８ａには、上記各主桁４，５，６の荷重が作用しなくなるため、この状態で、図６（ロ）に示すように、上記一方の端横桁８ａの長手方向両端部を、一方の外主桁４と中主桁５よりそれぞれ切り離すことで撤去する（ステップＡ８：ＳＡ８）。 Thereafter, as shown in FIG. 6 (a), another jack 20d is installed on the second end cross girder jack-up cradle 19b, and the other end cross girder 21b is newly installed by the jack 20d. On the other hand, the jack 20c on the first end cross-girder jack-up cradle 19a that has jacked up the existing one end cross-girder 8a is jacked down (step A7: SA7). As a result, the loads of the main girders 4, 5 and 6 are transferred from the outer main girders 4 and 6 via the jacks 20a and 20b and the outer main girder jack-up cradles 17 and the existing main girders. From the state of being transmitted and supported by the horizontal beam 3 from the one end cross beam 8a through the jack 20c and the first end cross beam jack-up cradle 19a, A load is applied to each of the outer main girders 4 and 6 through the jacks 20a and 20b and the outer main girder jack-up cradle 17 and from the other end lateral girder 21b to the jack 20d and the second load. Through the end cross girder jack-up cradle 19b, it is transferred to the horizontal beam 3 and supported. Therefore, the load of the main girders 4, 5 and 6 does not act on the existing one end lateral beam 8a. In this state, as shown in FIG. Both ends in the longitudinal direction of the beam 8a are removed from the outer main beam 4 and the middle main beam 5 respectively (step A8: SA8).

次いで、上記外主桁４と中主桁５の桁端縁部における上記既設の一方の端横桁８ａの撤去部分に必要に応じて補強を行ってから、図６（ハ）に示すように、上記一方の外主桁４と中主桁５の切欠き部１８，７の上側の桁端縁部同士の間に、橋幅方向に延びる新設の一方の端横桁２１ａを一体に取り付ける（ステップＡ９：ＳＡ９）。 Next, the outer main girder 4 and the middle main girder 5 are reinforced at the removed end portions of the one existing end girder 8a as necessary, as shown in FIG. The newly installed one end cross beam 21a extending in the bridge width direction is integrally attached between the upper edge portions of the notches 18 and 7 of the one outer main beam 4 and the middle main beam 5. Step A9: SA9).

なお、上記ステップＡ３（ＳＡ３）におけるジャッキアップ操作の後、上記ステップＡ９（ＳＡ９）までの間は、上記既設の各桁受ブラケット９ａ，９ｂ，９ｃ及びその上側の既設の各支承１０には、各主桁４，５，６の荷重が作用しない。このため、このステップＡ３（ＳＡ３）の後でステップ９（ＳＡ９）までの間の任意の時点で、必要に応じて上記既設の各桁受ブラケット９ａ，９ｂ，９ｃの図示しない補修や補強を行うと共に、該既設の各桁受ブラケット９ａ，９ｂ，９ｃ上の既設の各支承１０を、新規の支承１６に取り替えるようにして、支承１０の新規支承１６への取り替えによる機能回復と、支承周りの補強を行うようにすればよい。 After the jack-up operation in step A3 (SA3), until the step A9 (SA9), the existing girder brackets 9a, 9b, 9c and the existing supports 10 on the upper side thereof are The load of each main beam 4, 5, 6 does not act. For this reason, at any time between step A3 (SA3) and step 9 (SA9), the existing girder support brackets 9a, 9b, 9c (not shown) are repaired or reinforced as necessary. At the same time, the existing bearings 10 on the existing girder brackets 9a, 9b, 9c are replaced with new bearings 16 so that the functions can be restored by replacing the bearings 10 with the new bearings 16 and Reinforcement may be performed.

上記ステップＡ９（ＳＡ９）までの手順を終えることで既設の各端横桁８ａ，８ｂが新設の各端横桁２１ａ，２１ｂに取り替えられた後は、図７（イ）（ロ）に示すように、上記各外主桁ジャッキアップ用受台１７上の各ジャッキ２０ａ，２０ｂと、上記第２の端横桁ジャッキアップ用受台１９ｂ上の各ジャッキ２０ｃをジャッキダウンさせることで、上記新設の一方と他方の各端横桁２１ａ及び２１ｂと、中主桁５の桁端部を、それぞれ対応する桁受ブラケット９ａ及び９ｃと桁受ブラケット９ｂ上に設けた新規支承１６上に載置して支持させる（ステップＡ１０：ＳＡ１０）。しかる後、図７（ロ）に二点鎖線で示すように上記各ジャッキ２０ａ，２０ｂ，２０ｃ，２０ｄと、上記鋼製橋脚１の横梁３の橋軸方向面に設けてある上記各端横桁ジャッキアップ用受台１９ａ，１９ｂ及び各外主桁ジャッキアップ用受台１７をそれぞれ撤去して（ステップＡ１１：ＳＡ１１）、端横桁取替作業を終了する。 After the procedures up to step A9 (SA9) are completed and the existing end cross beams 8a and 8b are replaced with the newly installed end cross beams 21a and 21b, as shown in FIGS. The jacks 20a and 20b on the outer main girder jack-up cradle 17 and the jacks 20c on the second end cross-girder jack-up cradle 19b are jacked down so that the newly installed The one and the other end horizontal girders 21a and 21b and the middle end of the middle main girder 5 are placed on the new bearings 16 provided on the corresponding girder brackets 9a and 9c and the girder bracket 9b, respectively. Support (step A10: SA10). Thereafter, as shown by a two-dot chain line in FIG. 7 (b), the jacks 20a, 20b, 20c, 20d and the end cross beams provided on the bridge axial direction surface of the cross beam 3 of the steel pier 1 are provided. The jack-up cradle 19a, 19b and the outer main girder jack-up cradle 17 are removed (step A11: SA11), and the end cross girder replacement work is completed.

上記ステップＡ１ａ（ＳＡ１ａ）の手順にて、各外主桁４，６のフルウェブとなっている桁端の下部に切欠き部１８を新たに設ける場合は、該切欠き部１８を設けることで形成される桁端寄りの桁高急変部に掛かる各外主桁４，６の荷重に耐え得る剛性を確保できるようにするために、上記新設する切欠き部１８の周りとなる上記各外主桁４，６の桁端部付近を補強する必要がある。この点に鑑みて、本発明では、以下の図８（イ）（ロ）及び図９（イ）（ロ）に示す手順で上記各外主桁４，６に設ける切欠き部１８の周りを補強するようにしてある。 In the above-described step A1a (SA1a), when the notch 18 is newly provided at the lower part of the end of the spar that is the full web of the outer main girders 4 and 6, the notch 18 is provided. In order to ensure the rigidity that can withstand the load of the outer main girders 4 and 6 applied to the girder height suddenly changing portion near the end of the girder, the outer mains around the newly formed notch 18 are secured. It is necessary to reinforce the vicinity of the end portions of the girders 4 and 6. In view of this point, in the present invention, around the notch 18 provided in each of the outer main girders 4 and 6 in the procedure shown in FIGS. 8 (A) and (B) and FIGS. 9 (A) and 9 (B) below. It is designed to be reinforced.

すなわち、先ず、図８（イ）に示す如く、上記各外主桁４，６の桁端部付近の橋幅方向の外側面に、各主桁４，６の桁端下部に形成すべき切欠き部１８の形状に応じた切欠き部１８ａを有し、且つ該切欠き部１８ａに沿って下フランジ２３ａを備えた外主桁外側補強材２２を一体に取り付けるようにしてある。 That is, first, as shown in FIG. 8 (a), on the outer surface in the bridge width direction in the vicinity of the girder ends of the outer main girders 4 and 6, the cuts to be formed at the lower part of the girder ends of the main girders 4 and 6 are provided. An outer main girder outer reinforcing member 22 having a notch portion 18a corresponding to the shape of the notch portion 18 and having a lower flange 23a along the notch portion 18a is integrally attached.

次に、図８（ロ）に示す如く、上記各外主桁４，６の橋幅方向内側面の桁端部付近における各端横桁８ａ，８ｂよりも反横梁３側の領域に取り付けられているリブ状の既設補剛材２４を切断して撤去し、該既設補剛材２４の切断面をグラインダー等により平坦にした後、図９（イ）に示す如く、上記各外主桁４，６の橋幅方向内側面の桁端部付近における各端横桁８ａ，８ｂよりも反横梁３側の領域に、上記各外主桁４，６の桁端下部に形成すべき切欠き部１８の形状に応じた切欠き部１８ｂを有し、且つ該切欠き部１８ｂに沿って下フランジ２３ｂを備えた外主桁内側補強材２５を一体に取り付けるようにする。 Next, as shown in FIG. 8 (b), the outer main girders 4 and 6 are attached to the region on the side opposite to the transverse beam 3 from the end cross girders 8a and 8b in the vicinity of the girder end of the inner side surface in the bridge width direction. The rib-shaped existing stiffener 24 is cut and removed, and the cut surface of the existing stiffener 24 is flattened by a grinder or the like. Then, as shown in FIG. , 6 notch portions to be formed in the lower part of the spar of the outer main girders 4 and 6 in the region on the side opposite to the lateral beam 3 from the side spar 8a and 8b near the end of the spar on the inner side surface in the bridge width direction The outer main girder inner side reinforcement member 25 having a notch 18b corresponding to the shape of 18 and having a lower flange 23b along the notch 18b is integrally attached.

次いで、図９（ロ）に示すように、上記各外主桁４，６（図９（ロ）では他方の外主桁６についてのみ示してある）の桁端におけるウェブの下部を、上記外主桁４，６用の外側補強材２２と内側補強材２５の切欠き部１８ａ，１８ｂの形状に沿って切断して、該各外主桁４，６の桁端に、上記各補強材２２，２５により補強され且つ下フランジ２３ａ，２３ｂを備えた切欠き部１８を形成するようにしてある。 Next, as shown in FIG. 9 (b), the lower part of the web at the end of each outer main girder 4, 6 (only the other outer main girder 6 is shown in FIG. 9 (b)) The reinforcing members 22 are cut along the shapes of the outer reinforcing members 22 for the main girders 4 and 6 and the notches 18a and 18b of the inner reinforcing member 25. , 25 and a notch 18 having lower flanges 23a, 23b is formed.

更に、上記ステップＡ４（ＳＡ４）で、上記他方の外主桁６の橋幅方向内側面に取り付けてあった既設の他方の端横桁８ｂを撤去した状態のときに（図４（イ）参照）、図１０に示す如く、上記他方の外主桁６の橋幅方向内側面における上記既設の他方の端横桁８ｂの撤去部分から桁端までの領域に、上記新たに形成した切欠き部１８の上側に沿う下フランジ２３ｃを備えた外主桁内側桁端補強材２６を、その反横梁３側の端縁部を上記外主桁内側補強材２５の横梁３側端縁部に所要寸法重ねて配置した状態で、フィラープレート２７を介して一体に取り付けるようにする。又、図示してないが、上記一方の外主桁４についても同様に、上記ステップＡ８（ＳＡ８）で、上記一方の外主桁４の橋幅方向内側面に取り付けてある既設の一方の端横桁８ａを撤去した状態のときに（図６（ロ）参照）、上記一方の外主桁４の橋幅方向内側面における上記既設の一方の端横桁８ａの撤去部分から桁端までの領域に、上記新たに形成した切欠き部１８の上側に沿う下フランジ２３を備えた外主桁内側桁端補強材２６を、フィラープレート２７を介して一体に取り付けるようにすればよい。 Further, when the existing other end cross beam 8b attached to the inner surface of the other outer main girder 6 in the bridge width direction is removed in step A4 (SA4) (see FIG. 4 (a)). 10) As shown in FIG. 10, in the bridge width direction inner side surface of the other outer main girder 6, the newly formed notch is formed in a region from the removed portion of the existing other end cross girder 8b to the end of the girder. The outer main girder inner girder end reinforcing member 26 having the lower flange 23c along the upper side of the inner side 18 is connected to the side edge of the outer main girder inner reinforcing member 25 at the side edge of the outer main girder inner side reinforcing member 25. In a state where they are stacked, they are integrally attached via the filler plate 27. In addition, although not shown, the one outer main girder 4 is similarly attached to the one end of the existing outer main girder 4 attached to the inner side surface in the bridge width direction of the one outer main girder 4 in step A8 (SA8). When the cross beam 8a is removed (see FIG. 6 (b)), from the removed portion of the existing one end cross beam 8a on the inner side surface in the bridge width direction of the one outer main beam 4 to the end of the beam. The outer main girder inner spar end reinforcing member 26 having the lower flange 23 along the upper side of the newly formed notch 18 may be integrally attached to the region via the filler plate 27.

上記ステップＡ３（ＳＡ３）にて横梁３の橋軸方向面に設けた第１の端横桁ジャッキアップ用受台１９ａ上に設置したジャッキ２０ｃにより既設の一方の端横桁８ａをジャッキアップさせるときには、予め、上記既設の一方の端横桁８ａにおけるジャッキアップ個所のウェブと下フランジに図３（ロ）に示す如きリブ状の補強部材２８を取り付け、該ジャッキアップ個所の下フランジの下側に図示しない補強部材を取り付けて、上記既設の一方の端横桁８ａのジャッキアップ個所を補強するようにしてある。 When jacking up one existing end cross girder 8a with the jack 20c installed on the first end cross girder jack-up cradle 19a provided on the bridge axial direction surface of the cross beam 3 in step A3 (SA3) A rib-shaped reinforcing member 28 as shown in FIG. 3 (b) is attached in advance to the web and lower flange of the jack-up portion of the existing one end cross beam 8a, and the jack-up portion has a lower flange below the lower flange. A reinforcing member (not shown) is attached to reinforce the jack-up portion of the existing one end cross beam 8a.

又、上記ステップＡ５（ＳＡ５）の手順で中主桁５と他方の外主桁６の桁端縁部同士の間に取り付ける新設の他方の端横桁２１ｂは、後の工程であるステップＡ７（ＳＡ７）ので第２の端横桁ジャッキアップ用受台１９ｂ上に設置するジャッキ２０ｄにより該新設の他方の端横桁２１ｂをジャッキアップさせるときに作用する応力を考慮して、予めジャッキアップ個所が補強してあるものとする。 Further, the newly installed other end cross beam 21b attached between the end portions of the middle main beam 5 and the other outer main beam 6 in the procedure of step A5 (SA5) is the later step A7 ( SA7), considering the stress that acts when jacking up the other end cross beam 21b by the jack 20d installed on the second end cross beam jack-up cradle 19b, It shall be reinforced.

又、本発明では、上記中主桁５の既存の切欠き部７の周りに疲労による損傷が生じている場合であっても支承周りを補強できるようにするために、図１１（イ）（ロ）乃至図１４に示す手順で、上記中主桁５の桁端も補強するようにしてある。 Further, in the present invention, in order to be able to reinforce the periphery of the bearing even when the damage due to fatigue occurs around the existing notch portion 7 of the middle main girder 5, FIG. B) Through the procedure shown in FIG. 14, the end of the middle main beam 5 is also reinforced.

具体的には、図１１（イ）に示すように、先ず、上記中主桁５の橋幅方向の一側面の桁端部付近における一方の端横桁８ａよりも反横梁３側の領域に取り付けられているリブ状の既設補剛材２９ａを切断して撤去し、該既設補剛材２９ａの切断面をグラインダー等により平坦にした後、図１１（ロ）に示す如く、上記中主桁５の橋幅方向一側面の桁端部付近における上記一方の端横桁８ａよりも反横梁３側の領域に、上記中主桁５の既存の切欠き部７よりも一回り大きな切欠き部３１ａを有し、且つ該切欠き部３１ａの周りに下フランジ３２ａを備えた第１の中主桁補強材３０ａを一体に取り付けるようにする。 Specifically, as shown in FIG. 11 (a), first, in the area near the beam end of one side surface of the middle main beam 5 in the bridge width direction, the region closer to the side opposite the cross beam 3 than the one side beam 8a. After the attached rib-shaped existing stiffener 29a is cut and removed, and the cut surface of the existing stiffener 29a is flattened by a grinder or the like, as shown in FIG. A notch portion that is slightly larger than the existing notch portion 7 of the middle main girder 5 in a region on the side opposite to the transverse beam 3 than the one end cross beam 8a in the vicinity of the girder end portion on one side surface of the bridge width direction 5 A first middle main girder reinforcing member 30a having 31a and having a lower flange 32a around the notch 31a is integrally attached.

次に、上記中主桁５の橋幅方向の他側面の桁端部付近における他方の端横桁８ｂよりも反横梁３側の領域についても、上記と同様に、図１２（イ）に示す如く、リブ状の既設補剛材２９ｂを切断して撤去し、該既設補剛材２９ｂの切断面をグラインダー等により平坦にした後、図１２（ロ）に示す如く、上記中主桁５の橋幅方向他側面の桁端部付近における上記他方の端横桁８ｂよりも反横梁３側の領域に、上記中主桁５の既存の切欠き部７よりも一回り大きな切欠き部３１ｂを有し、且つ該切欠き部３１ｂの周りに下フランジ３２ｂを備えた第２の中主桁補強材３０ｂを一体に取り付けるようにする。 Next, the region on the side opposite to the lateral beam 3 with respect to the other side cross beam 8b in the vicinity of the beam end portion on the other side surface of the middle main beam 5 in the bridge width direction is also shown in FIG. After the rib-shaped existing stiffener 29b is cut and removed, and the cut surface of the existing stiffener 29b is flattened by a grinder or the like, as shown in FIG. A notch portion 31b that is slightly larger than the existing notch portion 7 of the middle main girder 5 is provided in the region on the side opposite to the transverse beam 3 than the other end cross girder 8b in the vicinity of the girder end portion on the other side surface in the bridge width direction. The second middle main girder reinforcing member 30b having the lower flange 32b around the notch 31b is integrally attached.

次いで、上記ステップＡ４（ＳＡ４）とステップＡ８（ＳＡ８）で上記中主桁５の橋幅方向両側面に取り付けてあった上記既設の他方の端横桁８ｂと既設の一方の端横桁８ａを順次撤去した状態のときに、図１３に示す如く、上記中主桁５の橋幅方向両側面における上記既設の他方の端横桁８ｂの撤去部分より桁端までの領域と、既設の一方の端横桁８ａの撤去部分より桁端までの領域に、上記各中主桁補強材３０ｂと３０ａの下フランジ３２ｂと３２ａと対応する下フランジ３２ｄと３２ｃをそれぞれ備えた中主桁桁端補強材３３ｂと３３ａを、その反横梁３側の端縁部を上記各中主桁補強材３０ｂと３０ａの横梁３側端縁部に所要寸法重ねて配置した状態で、フィラープレート３４を介在させて順次一体に取り付けるようにする。 Next, in step A4 (SA4) and step A8 (SA8), the existing other end cross beam 8b and the existing one end cross beam 8a attached to the both sides of the middle main girder 5 in the bridge width direction are When sequentially removed, as shown in FIG. 13, the area from the removed portion of the existing other end cross beam 8 b to the end of the bridge on both sides in the bridge width direction of the middle main girder 5 and one of the existing ones Middle main girder end reinforcing material provided with lower flanges 32d and 32c corresponding to the lower flanges 32b and 32a of the middle main girder reinforcing materials 30b and 30a in the region from the removed portion of the end cross beam 8a to the end of the girder, respectively. 33b and 33a are arranged sequentially with the filler plate 34 interposed in a state where the edge portion on the side opposite to the transverse beam 3 is arranged to overlap the edge portion on the transverse beam 3 side of each of the middle main girder reinforcing members 30b and 30a. Make sure they are attached together.

その後、図１４に示すように、上記各中主桁補強材３０ａ，３０ｂの切欠き部３１ａ，３１ｂ（図１１（ロ）及び図１２（ロ）参照）の周りの下フランジ３２ａ，３２ｂと、上記各中主桁桁端補強材３３ａ，３３ｂの下フランジ３２ｃ，３２ｄに沿う位置で、該中主桁５の桁端下部の既設の切欠き部７の周りのウェブを切断して、中主桁５の桁端に、上記中主桁５用の各補強材３０ａ，３０ｂ及び各桁端補強材３３ａ，３３ｂにより周りが強固に補強され、且つ下フランジ３２ａ，３２ｂ，３２ｃ，３２ｄを備えた新たな切欠き部７ａを形成できるようにしてある。なお、上記のようにして中主桁５の桁端に既設の切欠き部７よりも一回り大きな新たな切欠き部７ａを形成すると、該中主桁５の桁端における桁高が、当初の桁高よりも小さくなる。よって、その桁高の減少分は、上記新たに形成した切欠き部７ａを有する中主桁５の桁端を受ける上記新規支承１６の厚み寸法を、当初の支承１０の厚み寸法よりも厚く設定するか、あるいは図示しないソールプレートの厚み寸法を厚くすることで、上記中主桁５の上端の高さ位置が変化しないようにしてあるものとする。 Thereafter, as shown in FIG. 14, lower flanges 32a and 32b around the notches 31a and 31b (see FIGS. 11B and 12B) of the middle main girder reinforcing members 30a and 30b, At a position along the lower flanges 32c, 32d of the middle main girder end reinforcing members 33a, 33b, the web around the existing notch portion 7 below the middle end of the middle main girder 5 is cut, The girder 5 is provided with the lower flanges 32a, 32b, 32c, and 32d at the girder ends, the periphery of which is strongly reinforced by the reinforcing members 30a and 30b for the middle main girder 5 and the reinforcing members 33a and 33b. A new notch 7a can be formed. If a new notch 7a that is slightly larger than the existing notch 7 is formed at the end of the middle main girder 5 as described above, the girder height at the end of the middle main girder 5 is initially changed. It is smaller than the digit height. Therefore, the decrease in the girder height is set such that the thickness dimension of the new bearing 16 that receives the girder end of the middle main girder 5 having the newly formed notch portion 7a is thicker than the thickness dimension of the initial bearing 10. Alternatively, it is assumed that the height position of the upper end of the middle main girder 5 is not changed by increasing the thickness dimension of the sole plate (not shown).

上記のようにステップＡ４（ＳＡ４）とステップＡ８（ＳＡ８）で上記既設の各端横桁８ｂと８ａを順次撤去した状態のときに、各外主桁４，６の桁端の橋幅方向の内側面に上記外主桁内側桁端補強材２６を設け、上記中主桁５の桁端の橋幅方向の両側面に中主桁桁端補強材３３ａ，３３ｂを一体に取り付ける場合は、上記ステップＡ５（ＳＡ５）及びステップＡ９（ＳＡ９）で既設の各端横桁８ｂと８ａと取り替える新設の各端横桁２１ａ，２１ｂを設ける際に、該各新たな端横桁２１ａ，２１ｂの両端部を、上記外主桁４，６の内側面用と中主桁５用の各桁端補強材２６と３３ａ，３３ｂにそれぞれ取り付けるようにしてある。 As described above, in the state in which the existing end cross girders 8b and 8a are sequentially removed in step A4 (SA4) and step A8 (SA8), the bridge width direction of the girder ends of the outer main girders 4 and 6 When the outer main girder inner side girder end reinforcing member 26 is provided on the inner side surface and the middle main girder end reinforcing members 33a and 33b are integrally attached to both side surfaces in the bridge width direction of the girder end of the middle main girder 5, When providing the new end cross beams 21a and 21b to be replaced with the existing end cross beams 8b and 8a in step A5 (SA5) and step A9 (SA9), both end portions of the new end cross beams 21a and 21b are provided. Are attached to the girder end reinforcements 26 and 33a and 33b for the inner side surfaces of the outer main girders 4 and 6 and for the middle main girder 5, respectively.

このように、本発明の横桁取替方法によれば、鋼製橋脚１の横梁３に仮設する外主桁用と端横桁用のジャッキアップ用受台１７及び１９ａ，１９ｂ上に設置するジャッキ２０ａ，２０ｂ，２０ｃ，２０ｄのうちの所定のジャッキ２０ａ，２０ｂ，２０ｃにより各外主桁４，６と、既設の端横桁８ａ，８ｂのうちの片方、たとえば、既設の一方の端横桁８ａを先行してジャッキアップさせることにより、既設の他方の端横桁８ｂに主桁４，５，６の荷重がかからないようにした状態で該既設の他方の端横桁８ｂを、新設の他方の端横桁２１ｂに取り替え、その後、上記各主桁４，５，６の荷重を、上記各外主桁４，６をジャッキアップした状態の各ジャッキ２０ａ，２０ｂと、上記新設の他方の端横桁２１ｂをジャッキアップさせたジャッキ２０ｄに受替えることで、上記既設の一方の端横桁８ａに主桁４，５，６の荷重が掛からないようにした状態で、該既設の一方の端横桁８ａを、新設の一方の端横桁２１ａに取り替えることができるため、鋼製橋脚１の既設の横梁３の下側に増設横梁を取り付けるための上下方向のスペースが確保できないために主桁フルウェブ化工事を適用できないＩ桁橋においても、上記既設の各端横桁８ａ，８ｂの新設の各端横桁２１ａ，２１ｂへの取替作業を確実に実施することができる。 Thus, according to the cross girder replacement method of the present invention, it is installed on the jack-up cradle 17 and 19a, 19b for the outer main girder and the end cross girder temporarily installed on the cross beam 3 of the steel pier 1. Each of the outer main girders 4 and 6 and one of the existing end cross girders 8a and 8b, for example, one side of the existing end of the jacks 20a, 20b, 20c and 20d. By previously jacking up the girders 8a, the existing other end cross beam 8b is installed in a state where the load of the main girders 4, 5, 6 is not applied to the existing other end cross beam 8b. The other end horizontal girder 21b is replaced, and then the loads of the main girders 4, 5, 6 are changed to the jacks 20a, 20b with the outer main girders 4, 6 jacked up, and the other newly installed Jack 2 with end cross girder 21b jacked up In the state where the load of the main girders 4, 5 and 6 is not applied to the existing one end cross beam 8a, the existing one end cross beam 8a Because it can be replaced with the end cross girder 21a, the I-girder cannot be applied to the main girder full web construction because the vertical space for mounting the additional cross beam cannot be secured under the existing cross beam 3 of the steel pier 1 Even in the bridge, the above-described existing end cross beams 8a and 8b can be reliably replaced with the newly installed end cross beams 21a and 21b.

更に、上記各桁受ブラケット９ａ，９ｂ，９ｃの補修、補強や、その上側の既設の支承１０の新規支承１６への取り替えを行うことが可能になるため、支承１０の新規支承１６への取り替えによる機能回復と、支承周りの補強を行うことが可能になる。 Furthermore, since it becomes possible to repair and reinforce each girder bracket 9a, 9b, 9c and to replace the existing support 10 on the upper side with the new support 16, the replacement of the support 10 to the new support 16 is possible. It becomes possible to perform functional recovery and reinforce around the bearing.

次に、図１５乃至図２１（イ）（ロ）（ハ）は本発明の実施の他の形態として、図１乃至図１４の実施の形態の応用例を示すもので、既設の各端横桁８ａ，８ｂの新設の各端横桁２１ａ，２１ｂへの取り替えを行った後、該新設の各端横桁２１ａ，２１ｂと中主桁５の桁端とを、横梁３の各橋軸方向面に設置してある既設の桁受ブラケット９ａ，９ｃと桁受ブラケット９ｂに新規支承１６を介してそれぞれ支持させるようにする構成に代えて、既設の各端横桁８ａ，８ｂの新設の各端横桁２１ａ，２１ｂへの取り替えを行った後、各外主桁４，６の切欠き部１８を設けた桁端と、上記中主桁５の桁端とを、横梁３の各橋軸方向面に新設する外主桁４，６用の支点用ブラケット３５と、中主桁用の既設の桁受ブラケット９ｂに、新規支承１６を介してそれぞれ支持させるようにしたものである。 Next, FIGS. 15 to 21 (a), (b), and (c) show application examples of the embodiment of FIGS. 1 to 14 as other embodiments of the present invention. After replacing the newly installed end cross girders 21a and 21b of the girders 8a and 8b, the newly installed end cross girders 21a and 21b and the girder end of the middle main girder 5 are connected to each bridge axis direction of the cross beam 3. Instead of the configuration in which the existing girder brackets 9a, 9c and girder bracket 9b installed on the surface are supported by the new support 16 respectively, each of the existing end girder 8a, 8b is newly installed. After the replacement to the end cross girders 21a and 21b, the girder end provided with the notch 18 of each of the outer main girders 4 and 6 and the girder end of the middle main girder 5 are connected to each bridge shaft of the cross beam 3. The new bearing 16 is mounted on the fulcrum bracket 35 for the outer main girders 4 and 6 newly installed on the direction surface and the existing girder bracket 9b for the middle main girder. It is obtained so as to support each.

図１５は手順のフローを示すもので、図１に示したステップＡ１（ＳＡ１）からステップＡ９（ＳＡ９）までと同様の手順において、ステップＡ３（ＳＡ３）におけるジャッキアップ操作によって既設の各桁受ブラケット９ａ，９ｃと、その上の既設の各支承１０に各主桁４，５，６の荷重が掛からない状態となる上記ステップＡ３（ＳＡ３）より後の所要の時点で、既設の各端横桁８ａ，８ｂの支持に用いられていた既設の各桁受ブラケット９ａ，９ｃと、その上の既設の支承１０をそれぞれ撤去する。 FIG. 15 shows a flow of the procedure. In the procedure similar to that from step A1 (SA1) to step A9 (SA9) shown in FIG. 1, each existing girder bracket is obtained by the jack-up operation in step A3 (SA3). 9a, 9c, and each existing end cross beam at a required time after step A3 (SA3) where the loads of the main girders 4, 5, 6 are not applied to the existing support 10 on the upper side. The existing girder brackets 9a and 9c used for supporting 8a and 8b and the existing support 10 thereon are removed.

すなわち、たとえば、ステップＡ４（ＳＡ４）における既設の他方の端横桁８ｂの撤去に続いて、図１６に示すように、該既設の他方の端横桁８ｂに対応する既設の桁受ブラケット９ｃとその上側の既設の支承１０を撤去しておくようにする（ステップＡ４ａ：ＳＡ４ａ）。又、ステップＡ８（ＳＡ８）における既設の一方の端横桁８ａの撤去に続いて、図１７に示すように、該既設の一方の端横桁８ａに対応する既設の桁受ブラケット９ａとその上側の既設の支承１０を撤去しておくようにする（ステップＡ８ａ：ＳＡ８ａ）。 That is, for example, following the removal of the existing other end cross beam 8b in step A4 (SA4), as shown in FIG. 16, the existing beam receiving bracket 9c corresponding to the other end side cross beam 8b, The existing support 10 on the upper side is removed (step A4a: SA4a). Further, following the removal of the existing one end cross beam 8a in step A8 (SA8), as shown in FIG. 17, the existing beam receiving bracket 9a corresponding to the existing one end cross beam 8a and the upper side thereof. The existing support 10 is removed (step A8a: SA8a).

その後、上記ステップＡ９（ＳＡ９）までの手順を進めることにより、既設の各端横桁８ａ，８ｂが新設の各端横桁２１ａ，２１ｂに取り替えられた後は、図１８（イ）に示すように、鋼製橋脚１の横梁３に設けてある第１の端横桁ジャッキアップ用受台１９ａ上に設置してあるジャッキ２０ｃにより、新設の一方の端横桁２１ａのジャッキアップを行う一方、各外主桁４，６をジャッキアップしていた各主桁用ジャッキアップ用受台１７上のジャッキ２０ａ，２０ｂをジャッキダウンする（ステップＡ１２：ＳＡ１２）。これにより、上記各主桁４，５，６の荷重が、各外主桁４，６より各ジャッキ２０ａ，２０ｂと各外主桁ジャッキアップ用受台１７を介して、又、上記新設の他方の端横桁２１ｂよりジャッキ２０ｄと第２の端横桁ジャッキアップ用受台１９ｂを介して、それぞれ上記横梁３に伝えられて支持されていた状態から、該各主桁４，５，６の荷重が、上記新設の各端横桁２１ａ，２１ｂよりそれぞれ対応する各ジャッキ２０ｃ、２０ｄと第１と第２の各端横桁ジャッキアップ用受台１９ａ，１９ｂを介して上記横梁３に伝えられて支持される状態に受替えられるようになる。よって、上記各外主桁用ジャッキアップ用受台１７及びその上の各ジャッキ２０ａ，２０ｂには上記各主桁４，５，６の荷重が作用しなくなるため、この状態で、図１８（ロ）に示すように、上記横梁３の各橋軸方向面より上記各外主桁用ジャッキアップ用受台１７及びその上の各ジャッキ２０ａ，２０ｂを撤去する（ステップＡ１３：ＳＡ１３）。 Thereafter, by proceeding with the procedure up to step A9 (SA9), after the existing end cross beams 8a and 8b are replaced with the newly installed end cross beams 21a and 21b, as shown in FIG. In addition, the jack 20c installed on the first end cross girder jack-up cradle 19a provided on the cross beam 3 of the steel pier 1 is used to jack up the new one end cross girder 21a, The jacks 20a and 20b on the main girder jack-up cradle 17 that have jacked up the outer main girders 4 and 6 are jacked down (step A12: SA12). As a result, the loads of the main girders 4, 5 and 6 are transferred from the outer main girders 4 and 6 through the jacks 20a and 20b and the outer main girder jack-up receiving base 17, and the other newly installed From the state where the main beams 4, 5 and 6 are supported by being transmitted to and supported by the cross beam 3 from the end cross beam 21b via the jack 20d and the second end cross beam jack-up cradle 19b. The load is transmitted to the cross beam 3 from the newly installed end cross beams 21a and 21b via the corresponding jacks 20c and 20d and the first and second end cross beam jack up stands 19a and 19b, respectively. To be supported. Accordingly, since the loads of the main girders 4, 5, and 6 do not act on the outer main girder jack-up receiving base 17 and the upper jacks 20a, 20b thereon, in this state, FIG. ), The outer main girder jack-up cradle 17 and the jacks 20a and 20b thereon are removed from the bridge axial direction surfaces of the horizontal beams 3 (step A13: SA13).

その後、上記のようにして各外主桁用ジャッキアップ用受台１７とジャッキ２０ａ，２０ｂ、及び、既設の端横桁８ａ，８ｂにそれぞれ対応していた既設の桁受ブラケット９ａ，９ｃと既設の支承１０が撤去された状態で、図１９（イ）（ロ）に示すように、上記鋼製橋脚１の横梁３の各橋軸方向面における上記各外主桁４，６の切欠き部１８を設けた桁端の直下となる位置に、外主桁４，６用の支点用ブラケット３５をそれぞれ取り付け、その上側に新規支承１６を設置する（ステップＡ１４：ＳＡ１４）。更に、この際、中主桁５の桁端には、図１１乃至図１４に示したと同様の手順で補修、補強を施して新たな切欠き部７ａを形成しておくようにすると共に、該中主桁５に対応する既設の桁受ブラケット９ｂに後述する所要の補強を施し、該桁受ブラケット９ｂ上の支承１０の新規支承１６への取り替えを行うようにする。 After that, the outer main girder jack-up cradle 17 and the jacks 20a and 20b and the existing girder brackets 9a and 9c and the existing girder brackets 9a and 9c respectively corresponding to the existing end cross beams 8a and 8b are installed. With the support 10 removed, as shown in FIGS. 19 (a) and 19 (b), the notch portions of the outer main girders 4 and 6 on the bridge axial direction surfaces of the cross beam 3 of the steel pier 1 are provided. The fulcrum brackets 35 for the outer main girders 4 and 6 are respectively attached to positions directly below the end of the spar provided with 18 and the new support 16 is installed on the upper side thereof (step A14: SA14). Further, at this time, at the end of the middle main beam 5, repair and reinforcement are performed in the same procedure as shown in FIGS. 11 to 14 to form a new notch 7 a, and Necessary reinforcement described later is applied to the existing girder bracket 9b corresponding to the middle main girder 5, and the bearing 10 on the girder bracket 9b is replaced with a new bearing 16.

その後、図２０に示すように、上記新設の各端横桁２１ａ，２１ｂをジャッキアップしている各ジャッキ２０ｃ，２０ｄをジャッキダウンさせることで、上記各外主桁４，６の桁端を、上記横梁３に新設した各支点用ブラケット３５上の新規支承１６の上に載置して支持させると共に、中主桁５の桁端を、補強後の桁受ブラケット９ｂ上の新規支承１６の上に載置して支持させるようにする（ステップＡ１５：ＳＡ１５）。 Then, as shown in FIG. 20, the jack ends of the outer main girders 4 and 6 are lowered by jacking down the jacks 20c and 20d jacking up the newly installed end transverse girders 21a and 21b. It is placed on and supported by the new support 16 on each fulcrum bracket 35 newly provided on the transverse beam 3, and the end of the middle main girder 5 is placed on the new support 16 on the reinforced girder bracket 9b. (Step A15: SA15).

しかる後、上記各端横桁ジャッキアップ用受台１９ａ，１９ｂとその上のジャッキ２０ｃ、２０ｄをそれぞれ撤去して（ステップＡ１６：ＳＡ１６）、端横桁取替作業、及び、支承取替作業を終了する。これにより、図２１（イ）（ロ）（ハ）に示すように、各主桁４と５及び各主桁５と６の桁端縁部同士が取り替えられた新設の端横桁２１ａ，２１ｂにより連結され、且つ上記各外主桁４，６の新たに切欠き部１８を設けた桁端を、鋼製橋脚１の横梁３の橋軸方向面における下部所要個所に設けた支点用ブラケット３５の上側に新規支承１６を介してそれぞれ支持させ、且つ上記中主桁５の補強された切欠き部７ａが設けてある桁端を、上記補強した桁受ブラケット９ｂの上側に新規支承１６を介して支持させ、更に、既設の端横桁８ａ，８ｂを支持していた既設の各桁受ブラケット９ａ，９ｃが撤去された構成を有するＩ桁橋が形成されるようになる。 After that, each of the end cross girder jack-up receiving bases 19a and 19b and the jacks 20c and 20d thereon are removed (step A16: SA16), and the end cross girder replacement work and the bearing replacement work are performed. finish. As a result, as shown in FIGS. 21 (a), (b), and (c), the new end cross beams 21a and 21b in which the main edge portions 4 and 5 and the main edge portions 5 and 6 are replaced with each other. , And a fulcrum bracket 35 provided at the lower required position in the bridge axial direction surface of the cross beam 3 of the steel pier 1 with the end of the outer main girder 4 and 6 provided with the notch 18 newly provided. The upper end of the spar is supported by the new support 16 and the reinforced notch portion 7a of the middle main girder 5 is provided on the upper side of the reinforced girder bracket 9b via the new support 16. Further, an I-girder bridge having a configuration in which the existing girder receiving brackets 9a and 9c supporting the existing end cross beams 8a and 8b are removed is formed.

上記ステップＡ１４（ＳＡ１４）にて、鋼製橋脚１の横梁３の各橋軸方向面に各外主桁４，６用の支点用ブラケット３５を設ける場合は、図１９（ロ）に示す如く、上記横梁３の各橋軸方向面の下部所定個所に、上記各支点用ブラケット３５を、それぞれ下端側が上記横梁３の下方へ所要寸法突出するように配置して取り付けると共に、該各外主桁用支点用ブラケット３５の下端突出部の横梁３を挟んで橋軸方向に対応するもの同士の間に、上記横梁３の下側を通って橋軸方向に延びる連結部材３６を配置し、該連結部材３６の長手方向両端部を上記各支点用ブラケット３５の下端突出部にそれぞれ一体に取り付けると共に、該連結部材３６の上端部を上記横梁３の下フランジの下側に一体に取り付けるようにしてある。更に、上記横梁３の各橋軸方向面における上記各支点用ブラケット３５の取付個所の内側となる該横梁３のウェブ内面の所要個所同士の間に、横梁３内で橋軸方向に延びる横梁内部補強材３７を配置して、その長手方向両端部を上記横梁３のウェブ内面の所要個所にそれぞれ一体に取り付けると共に、該横梁内部補強材３７の下端部を、上記横梁３の下フランジの上面に一体に取り付けることで、支承周りとなる上記横梁３における上記各支点用ブラケット３５の設置個所を補強することができるようにしてある。 In step A14 (SA14), when the fulcrum brackets 35 for the outer main girders 4 and 6 are provided on each bridge axial direction surface of the cross beam 3 of the steel pier 1, as shown in FIG. The fulcrum brackets 35 are mounted at predetermined locations below the bridge-axis-direction surfaces of the horizontal beams 3 so that their lower ends protrude below the horizontal beams 3 with required dimensions, and for the outer main girders. A connecting member 36 extending in the bridge axis direction through the lower side of the horizontal beam 3 is disposed between the members corresponding to the bridge axis direction across the horizontal beam 3 of the lower end protruding portion of the fulcrum bracket 35, and the connecting member Both end portions in the longitudinal direction of 36 are integrally attached to the lower end protruding portions of the fulcrum brackets 35, and the upper end portion of the connecting member 36 is integrally attached to the lower side of the lower flange of the transverse beam 3. Further, the interior of the transverse beam extending in the direction of the bridge axis in the transverse beam 3 between the required locations on the inner surface of the web of the transverse beam 3 which is the inside of the attachment portion of the bracket 35 for each fulcrum on each bridge axis direction surface of the transverse beam 3. Reinforcing members 37 are arranged, and both longitudinal ends thereof are integrally attached to required portions of the inner surface of the web of the cross beam 3, and the lower ends of the cross beam internal reinforcing members 37 are attached to the upper surface of the lower flange of the cross beam 3. By attaching them integrally, it is possible to reinforce the installation locations of the fulcrum brackets 35 in the transverse beam 3 around the support.

上記中主桁５の桁端を支持するために鋼製橋脚１の横梁３の各橋軸方向面に設けてある既設の桁受ブラケット９ｂを補強する場合は、たとえば、図１９（ハ）に示す如く、上記横梁３の橋軸方向の両面に設けてある各桁受ブラケット９ｂの下側に、上記横梁３の下フランジの下側を通して一連に延びる桁受ブラケット補強部材３８を配置すると共に、該桁受ブラケット補強部材３８の上端部を、上記橋幅方向中央の各桁受ブラケット９ｂの下側及び上記横梁３の下フランジの下面に一体に取り付けて、上記各桁受ブラケット９ｂの補強を行うようにしてある。 In order to reinforce the existing girder bracket 9b provided on each bridge axial direction surface of the cross beam 3 of the steel pier 1 in order to support the end of the middle main girder 5, for example, as shown in FIG. As shown in the figure, a girder bracket reinforcing member 38 extending in series through the lower side of the lower flange of the horizontal beam 3 is arranged below each girder bracket 9b provided on both sides in the bridge axis direction of the horizontal beam 3, The upper end portion of the girder bracket reinforcing member 38 is integrally attached to the lower side of each girder bracket 9b in the center in the bridge width direction and the lower surface of the lower flange of the transverse beam 3 to reinforce each girder bracket 9b. To do.

その他、図１乃至図１４に示したものと同一のものには同一符号が付してある。 Other components that are the same as those shown in FIGS. 1 to 14 are denoted by the same reference numerals.

このように、本実施の形態によれば、上記実施の形態と同様の効果を得ることができ、更に、各外主桁４，６の桁端を、鋼製橋脚１の横梁３の橋軸方向面に新設する各支点用ブラケット３５に上記新規支承１６を介して支持させることができると共に、中主桁５の桁端を補強した桁受ブラケット９ｂに新規支承１６を介して支持させることができるため、各主桁４，５，６の荷重を支持する支承１０の新規支承１６への取り替えを行うことで機能回復を図ることができると共に、支承周りの補強を実施することが可能になる。 Thus, according to the present embodiment, the same effects as those of the above-described embodiment can be obtained, and furthermore, the girder ends of the outer main girders 4 and 6 are connected to the bridge shaft of the cross beam 3 of the steel pier 1. Each of the fulcrum brackets 35 newly provided on the directional surface can be supported via the new support 16, and can be supported via the new support 16 on the girder bracket 9 b in which the end of the middle main girder 5 is reinforced. Therefore, it is possible to recover the function by replacing the bearing 10 supporting the loads of the main girders 4, 5 and 6 with the new bearing 16, and to reinforce the bearings. .

図２２乃至図３０（イ）（ロ）（ハ）は本発明の実施の更に他の形態を示すもので、図２２にフローを示す如き手順としてある。 22 to 30 (a), (b), and (c) show still another embodiment of the present invention, and the procedure is as shown in the flow chart of FIG.

すなわち、図３５（イ）（ロ）（ハ）及び図３６に示したと同様に、桁端がフルウェブの外主桁４，６と、桁端に切欠き部７を有する中主桁５とを備えて、鋼製橋脚１の横梁３における橋軸方向面に突設した桁受ブラケット９ａ，９ｂ，９ｃに、上記中主桁５の切欠き部７の上側の桁端、及び、上記中主桁５と各外主桁４，６の桁端縁部同士を接続する端横桁８ａ，８ｂの橋幅方向外側端部寄り個所を、支承１０を介してそれぞれ支持させるようにしてなる構成のＩ桁橋における上記各外主桁４，６の桁端の下部に、図２３（イ）（ロ）に示す如く、切欠き部１８をそれぞれ設ける（ステップＢ１：ＳＢ１）。なお、該各外主桁４，６の桁端に切欠き部１８を設ける場合は、図８乃至図１０に示したと同様の手順で行うようにすればよい。 That is, as shown in FIGS. 35 (A), (B), (C) and FIG. 36, the outer main girders 4 and 6 with full webs at the end of the web and the middle main girders 5 having the notches 7 at the end of the girders. The beam support brackets 9a, 9b, and 9c projecting on the bridge axial direction surface of the cross beam 3 of the steel pier 1 are connected to the upper end of the notch 7 of the middle main beam 5 and the middle A configuration in which the positions near the outer end in the bridge width direction of the end cross girders 8a and 8b that connect the end edges of the main girder 5 and the outer main girders 4 and 6 are supported via the support 10, respectively. As shown in FIGS. 23 (A) and 23 (B), notches 18 are respectively provided at the lower ends of the outer main girders 4 and 6 in the I-girder bridge (step B1: SB1). In addition, what is necessary is just to carry out in the same procedure as shown in FIG. 8 thru | or FIG.

次に、鋼製橋脚１の横梁３の各橋軸方向面における上記各外主桁４，６の桁端の直下となる所要個所に、上記各外主桁４，６に設けた切欠き部１８の内側で橋軸方向に突出する新規桁受ブラケット３９をそれぞれ設ける（ステップＢ２：ＳＢ２）。なお、上記横梁における上記新規桁受ブラケット３９の取り付け個所は、図１９に示した横梁３の支点用ブラケット３５の取り付け個所と同様に、連結部材３６と横梁内部補強材３７で補強するようにしてあるものとする。 Next, the notch portions provided in the outer main girders 4 and 6 are provided at required positions directly below the beam ends of the outer main girders 4 and 6 on the respective bridge axial directions of the cross beams 3 of the steel pier 1. A new girder bracket 39 that protrudes in the direction of the bridge axis is provided inside 18 (step B2: SB2). The mounting position of the new girder bracket 39 in the horizontal beam is reinforced by the connecting member 36 and the horizontal beam internal reinforcing material 37 in the same manner as the mounting position of the fulcrum bracket 35 of the horizontal beam 3 shown in FIG. It shall be.

又、図２３（イ）（ハ）に示す如く、上記横梁３の各橋軸方向面における上記既設の各端横桁８ａ，８ｂの橋幅方向内側端部寄り個所と対応する個所の下部位置に、図２（イ）（ロ）（ハ）に示した第１の端横桁ジャッキアップ用受台１９ａ及び図５（イ）（ロ）に示した第２の端横桁ジャッキアップ用受台１９ｂと同様の端横桁ジャッキアップ用受台１９ａ及び１９ｂを、上記各端横桁８ａ，８ｂの下方位置まで突出させてそれぞれ設ける（ステップＢ３：ＳＢ３）。 Further, as shown in FIGS. 23 (a) and 23 (c), the lower position of the portion corresponding to the portion closer to the inner end portion in the bridge width direction of each of the existing end cross girders 8a and 8b on each bridge axial direction surface of the cross beam 3 2 (a), (b) and (c), the first end cross beam jack up receiving base 19a and the second end cross beam jack up receiver shown in FIGS. The end cross girder jack-up receiving bases 19a and 19b similar to the base 19b are provided so as to protrude to the positions below the end cross girders 8a and 8b (step B3: SB3).

更に、図２３（イ）（ロ）に二点鎖線で示すように、上記各外主桁４，６における桁端より所要寸法離れた個所の橋幅方向の外側面に、上記横梁３の近傍まで延びるアウトリガー４０をそれぞれ仮設する（ステップＢ４：ＳＢ４）。この際、上記外主桁４，６における上記アウトリガー４０の取り付け個所を補強するために、図２３（イ）（ハ）に二点鎖線で示すように、上記各外主桁４，６の桁端より所要寸法離れた個所の橋幅方向の内側面と、上記中主桁５の桁端より所要寸法離れた個所の橋幅方向両側面との間に、それぞれ橋幅方向に延びる仮設横桁４１を配置して、該各仮設横桁４１の両端部を、上記各外主桁４，６の橋幅方向内側面と、上記中主桁５の橋幅方向の両側面にそれぞれ取り付けておくようにする。 Further, as shown by the two-dot chain line in FIGS. 23 (a) and 23 (b), in the vicinity of the cross beam 3 on the outer side surface in the bridge width direction at a position away from the end of each of the outer main girders 4 and 6 by a required dimension. Each of the outriggers 40 extending to the temporary position is temporarily installed (step B4: SB4). At this time, in order to reinforce the attachment position of the outrigger 40 in the outer main girders 4 and 6, as shown by two-dot chain lines in FIGS. Temporary cross girders extending in the bridge width direction between the inner side surface in the bridge width direction at the required distance from the end and both side surfaces in the bridge width direction at the required distance from the girder edge of the middle main girder 5 41, and both end portions of the temporary horizontal girders 41 are respectively attached to the inner side surfaces of the outer main girders 4 and 6 in the bridge width direction and the both side surfaces of the middle main girder 5 in the bridge width direction. Like that.

一方、上記横梁３の各橋軸方向面における上記各アウトリガー４０と対応する橋幅方向両端寄り所要個所の下部位置には、上記各アウトリガー４０の下方位置まで突出するジャッキアップ用受台４２を、たとえば、上記新規桁受ブラケット３９と一体物として設ける（ステップＢ５：ＳＢ５）。 On the other hand, at the lower position of the necessary position near the both ends in the bridge width direction corresponding to each of the outriggers 40 on each bridge axial direction surface of the horizontal beam 3, a jack-up cradle 42 protruding to a position below each of the outriggers 40 is provided. For example, the new girder bracket 39 is provided as an integral part (step B5: SB5).

その後、図２４（イ）（ロ）に示す如く、上記各アウトリガー４０の下方に位置する各ジャッキアップ用受台４２と、上記既設の一方の端横桁８ａの下方に位置する第１の端横桁ジャッキアップ用受台１９ａに、それぞれジャッキ４３ａ，４３ｂとジャッキ４３ｃをそれぞれ設置して、該各ジャッキ４３ａ，４３ｂ，４３ｃにより、その上方の上記各アウトリガー４０及び上記既設の一方の端横桁８ａを介して上記各主桁４，５，６を同時にジャッキアップする（ステップＢ６：ＳＢ６）。これにより、上記各主桁４，５，６の荷重は、上記各アウトリガー４０より上記各ジャッキ４３ａ，４３ｂと各ジャッキアップ用受台４２を介して、又、上記既設の一方の端横桁８ａより上記ジャッキ４３ｃと第１の端横桁ジャッキアップ用受台１９ａを介して、それぞれ上記鋼製橋脚１の横梁３に伝えられて支持されるようになる。よって、既設の他方の端横桁８ｂ、及び、既設の各桁受ブラケット９ａ，９ｂ，９ｃとその上の支承１０には上記各主桁４，５，６からの荷重が作用しなくなるため、この状態で、図２５（イ）に示す如く、各既設の端横桁８ａ，８ｂの支持に用いられていた既設の各桁受ブラケット９ａ及び９ｃと、その上側の各支承１０を撤去する（ステップＢ７：ＳＢ７）。 Thereafter, as shown in FIGS. 24 (a) and 24 (b), the jack-up pedestals 42 positioned below the respective outriggers 40 and the first ends positioned below the existing one end cross beam 8a. The jacks 43a, 43b and the jack 43c are respectively installed on the cross beam jack-up cradle 19a. The jacks 43a, 43b and 43c allow the outriggers 40 above and one of the existing end cross girders. The main girders 4, 5 and 6 are jacked up simultaneously via 8a (step B6: SB6). As a result, the loads of the main girders 4, 5, and 6 are supplied from the outriggers 40 through the jacks 43a and 43b and the jack-up pedestals 42, and the existing one end cross beam 8a. Further, it is transmitted to and supported by the horizontal beam 3 of the steel pier 1 through the jack 43c and the first end cross beam jack up cradle 19a. Therefore, the load from the main girders 4, 5 and 6 does not act on the existing other end horizontal girder 8b and the existing girder brackets 9a, 9b, 9c and the support 10 thereon. In this state, as shown in FIG. 25 (a), the existing girder brackets 9a and 9c used for supporting the existing end cross beams 8a and 8b and the upper supports 10 are removed ( Step B7: SB7).

次いで、図２５（ロ）に示すように、上記各主桁４，５，６の荷重が作用しなくなった状態の既設の他方の端横桁８ｂを、その長手方向両端部を中主桁５と他方の外主桁６よりそれぞれ切り離すことで撤去し（ステップＢ８：ＳＢ８）、その後、上記中主桁５及び他方の外主桁６における上記既設の他方の端横桁８ｂの撤去部分に、図１１（イ）（ロ）乃至図１４に示したと同様の手順や、図８（イ）（ロ）乃至図１０に示したと同様の手順による所要の補強を行ってから、図２５（ハ）に示すように、該中主桁５と他方の外主桁６の各切欠き部７，１８の上側の補強された桁端縁部同士の間に、橋幅方向に延びる新設の他方の端横桁２１ｂを一体に取り付ける（ステップＢ９：ＳＢ９）。 Next, as shown in FIG. 25 (b), the existing other end cross beam 8b in a state where the load of each of the main girders 4, 5 and 6 does not act on the middle main girder 5 at both longitudinal ends thereof. And the other outer main girder 6 are removed by separating them from each other (step B8: SB8), and then, in the removed portion of the existing other end horizontal girder 8b in the middle main girder 5 and the other outer main girder 6, After performing necessary reinforcement by the same procedure as shown in FIGS. 11 (a) to (b) to 14 and the same procedure as shown in FIGS. 8 (a) to (b) to FIG. As shown in Fig. 2, the other end of the newly installed extending in the width direction of the bridge between the reinforced end portions of the upper notches 7 and 18 of the middle main girder 5 and the other outer main girder 6 The cross beam 21b is attached integrally (step B9: SB9).

上記のようにして既設の他方の端横桁８ｂが新設の他方の端横桁２１ｂに取り替えられた後は、図２６（イ）に示すように、上記新設の他方の端横桁２１ｂの下方に位置する第２の端横桁ジャッキアップ用受台１９ｂ上に別のジャッキ４３ｄを設置して、該ジャッキ４３ｄにより上記新設の他方の端横桁２１ｂのジャッキアップを行う一方、上記既設の一方の端横桁８ａをジャッキアップしていた上記第１の端横桁ジャッキアップ用受台１９ａ上のジャッキ４３ｃをジャッキダウンする（ステップＢ１０：ＳＢ１０）。これにより、上記各主桁４，５，６の荷重が、各アウトリガー４０より各ジャッキ４３ａ，４３ｂと各ジャッキアップ用受台４２を介して、又、上記既設の一方の端横桁８ａよりジャッキ４３ｃと第１の端横桁ジャッキアップ用受台１９ａを介してそれぞれ上記横梁３に伝えられて支持されていた状態から、該各主桁４，５，６の荷重が、上記各アウトリガー４０より各ジャッキ４３ａ，４３ｂと各ジャッキアップ用受台４２を介して、又、上記新設の他方の端横桁２１ｂよりジャッキ４３ｄと第２の端横桁ジャッキアップ用受台１９ｂを介して、それぞれ上記横梁３に伝えられて支持される状態に受替えられるようになる。 After the existing other end cross beam 8b is replaced with the new other end cross beam 21b as described above, as shown in FIG. 26 (a), below the new other end cross beam 21b. Another jack 43d is installed on the second end cross-girder jack-up cradle 19b located at a position, and the other end cross-girder 21b is jacked up by the jack 43d. The jack 43c on the cradle 19a for the first end cross girder jack up which has been jacked up the end cross girder 8a is jacked down (step B10: SB10). As a result, the loads of the main girders 4, 5, 6 are jacked from the outriggers 40 via the jacks 43a, 43b and the jack-up cradle 42, and from the existing one end lateral girder 8a. 43c and the first end cross-girder jack-up cradle 19a are transmitted to and supported by the cross beam 3, and the loads of the main girders 4, 5 and 6 are applied from the outriggers 40, respectively. Via the jacks 43a and 43b and the jack-up cradle 42, or from the other newly installed end cross-girder 21b via the jack 43d and the second end cross-girder jack-up cradle 19b, respectively. The state is transferred to the horizontal beam 3 and supported.

よって、上記既設の一方の端横桁８ａ及び第１の端横桁ジャッキアップ用受台１９ａ上のジャッキ４３ｃには、上記各主桁４，５，６の荷重が作用しなくなるため、この状態で、図２６（ロ）に示すように、上記ジャッキ４３ｃを撤去する（ステップＢ１１：ＳＢ１１）。更に、図２７（イ）に示すように、上記各主桁４，５，６の荷重が作用しなくなった状態の既設の一方の端横桁８ａを、その長手方向両端部を一方の外主桁４と中主桁５よりそれぞれ切り離すことで撤去する（ステップＢ１２：ＳＢ１２）。 Therefore, the load of the main girders 4, 5 and 6 does not act on the jack 43c on the one end cross girder 8a and the first end cross girder jack-up cradle 19a. Then, as shown in FIG. 26 (b), the jack 43c is removed (step B11: SB11). Further, as shown in FIG. 27 (a), the existing one end cross beam 8a in a state in which the load of each of the main girders 4, 5 and 6 does not act on the both ends in the longitudinal direction is arranged on one outer main beam. It is removed by separating it from the girder 4 and the middle main girder 5 (step B12: SB12).

次いで、上記一方の外主桁４と中主桁５における上記既設の一方の端横桁８ａの撤去部分に、図１１（イ）（ロ）乃至図１４に示したと同様の手順や、図８（イ）（ロ）乃至図１０に示したと同様の手順による所要の補強を行ってから、図２７（ロ）に示すように、該一方の外主桁４と中主桁５の切欠き部１８，７の上側の補強された桁端縁部同士の間に、橋幅方向に延びる新設の一方の端横桁２１ａを一体に取り付ける（ステップＢ１３：ＳＢ１３）。 Next, the same procedure as shown in FIGS. 11 (A) to 11 (B) or FIG. 8 is applied to the removed portion of the existing one end cross beam 8a in the one outer main beam 4 and the middle main beam 5. (A) After performing the necessary reinforcement in the same procedure as shown in (B) to FIG. 10, as shown in FIG. 27 (B), the notched portions of the one outer main girder 4 and the middle main girder 5 A newly installed one end cross girder 21a extending in the bridge width direction is integrally attached between the reinforced girder edge portions on the upper side of 18 and 7 (step B13: SB13).

上記ステップＢ１３（ＳＢ１３）までの手順を終えることで既設の各端横桁８ａ，８ｂが各新設の端横桁２１ａ，２１ｂへ取り替えられた後は、図２８に示す如く、中主桁５支持用の各桁受ブラケット９ｂの上側に設置してある既設の支承１０を撤去すると共に、上記各桁受ブラケット９ｂの下側に、図１９（ハ）に示したと同様の桁受ブラケット補強部材３８を取り付けて、上記各桁受ブラケット９ｂの補強を行うようにする（ステップＢ１４：ＳＢ１４）。又、中主桁５の桁端を、図１１（イ）（ロ）乃至図１４に示したと同様の手順により補強すると共に、当初の切欠き部７より一回り大きな補強された切欠き部７ａを形成しておくようにする。 After the procedure up to the above step B13 (SB13) is completed and the existing end cross beams 8a and 8b are replaced with the new end cross beams 21a and 21b, the middle main beam 5 is supported as shown in FIG. The existing support 10 installed on the upper side of each girder bracket 9b is removed, and a girder bracket reinforcing member 38 similar to that shown in FIG. 19C is provided on the lower side of each girder bracket 9b. Is attached to reinforce each girder bracket 9b (step B14: SB14). Further, the end of the middle main girder 5 is reinforced by a procedure similar to that shown in FIGS. 11 (A) to 11 (B), and the reinforced notched portion 7a is slightly larger than the original notched portion 7. To form.

その後、図２９（イ）（ロ）に示すように、上記補強された中主桁５支持用の各桁受ブラケット９ｂの上側と、上記各新規桁受ブラケット３９の上側に、それぞれ新規の支承１６を設けた後、上記各アウトリガー４０と新設の他方の端横桁２１ｂをジャッキアップしている各ジャッキアップ用受台４２上のジャッキ４３ａ，４３ｂと第２の端横桁ジャッキアップ用受台１９ｂ上のジャッキ４３ｄをジャッキダウンすることで、上記各新規支承１６の上側に、上記中主桁５の切欠き部７ａの上側の桁端と、上記各外主桁４，６に新たに設けた切欠き部１８の上側の桁端をそれぞれ載置させて、上記中主桁５及び各外主桁４，６の荷重を、上記各新規支承１６と、上記補強された桁受ブラケット９ｂ及び上記各新規桁受ブラケット３９を介して上記鋼製橋脚１の横梁３に伝えて受けさせるようにする（ステップＢ１５：ＳＢ１５）。 After that, as shown in FIGS. 29 (A) and 29 (B), new supports are respectively provided on the upper side of each of the reinforced beam support brackets 9b for supporting the middle main beam 5 and on the upper side of each of the new beam support brackets 39. 16, jacks 43a and 43b on each jackup receiving base 42 jacking up each of the above outriggers 40 and the other newly installed end transverse girder 21b and the second end crossing girder jackup receiving base By jacking down the jack 43d on 19b, it is newly provided on the upper side of each new bearing 16, on the upper side of the notch 7a of the middle main beam 5 and on each of the outer main beams 4 and 6. The upper girder ends of the cutout portions 18 are respectively placed so that the loads of the middle main girder 5 and the outer main girder 4 and 6 are transferred to the new support 16 and the reinforced girder bracket 9b. Above each new girder bracket 39 So as to subject tell crossbeam 3 steel pier 1 (step B15: SB15).

上記のようにして各主桁４，５，６の荷重を、各新規支承１６、及び、桁受ブラケット９ｂ及び各新規桁受ブラケット３９を介して上記横梁３に支持させた後は、上記各端横桁ジャッキアップ用受台１９ａ，１９ｂ及び各アウトリガー４０及び各仮設横桁４１及び残りの各ジャッキ４３ａ，４３ｂ，４３ｄをそれぞれ撤去して（ステップＢ１６：ＳＢ１６）、端横桁取替作業、及び、支承取替作業を終了する。これにより、図３０（イ）（ロ）（ハ）に示すように、各主桁４と５及び各主桁５と６の桁端縁部同士が取り替えられた新設の端横桁２１ａ，２１ｂにより連結され、且つ上記各外主桁４，６の新たに切欠き部１８を設けた桁端を、鋼製橋脚１の横梁３の橋軸方向面における下部所要個所に設けた新規桁受ブラケット３９の上側に新規支承１６を介してそれぞれ支持させ、且つ上記中主桁５の補強された切欠き部７ａが設けてある桁端を、上記補強した桁受ブラケット９ｂの上側に新規支承１６を介して支持させ、更に、上記既設の各端横桁８ａ，８ｂを支持していた既設の各桁受ブラケット９ａ，９ｃが撤去された構成を有するＩ桁橋が形成されるようになる。 After the loads of the main girders 4, 5 and 6 are supported on the cross beam 3 through the new bearings 16 and the girder brackets 9b and the new girder brackets 39 as described above, The end cross girder jack-up cradle 19a, 19b, each outrigger 40, each temporary cross girder 41 and the remaining jacks 43a, 43b, 43d are respectively removed (step B16: SB16), and the end cross girder replacement work is performed. And the bearing replacement work is finished. As a result, as shown in FIGS. 30 (a), (b), and (c), new end cross beams 21a and 21b in which the end portions of the main beams 4 and 5 and the main beam 5 and 6 are replaced with each other. And a new girder bracket in which the end of the outer main girder 4 and 6 provided with a notch 18 is provided at a lower required position in the bridge axial direction of the cross beam 3 of the steel pier 1. The upper end of 39 is supported by a new support 16 and the end of the middle main girder 5 is provided with a reinforced notch 7a. The new support 16 is mounted on the upper side of the reinforced girder bracket 9b. Further, an I-girder bridge having a configuration in which the existing girder brackets 9a and 9c supporting the existing end cross beams 8a and 8b are removed is formed.

その他、図１６乃至図２１（イ）（ロ）（ハ）に示したものと同一のものには同一符号が付してある。 In addition, the same components as those shown in FIGS. 16 to 21 (a), (b), and (c) are denoted by the same reference numerals.

このように、本実施の形態によっても、図１乃至図１４の実施の形態と同様の効果を得ることができ、更に、各外主桁４，６の桁端を、鋼製橋脚１の横梁３の橋軸方向面に新設する各新規桁受ブラケット３９に新規支承１６を介して支持させることができると共に、中主桁５の桁端を補強した桁受ブラケット９ｂに新規支承１６を介して支持させることができるため、各主桁４，５，６の荷重を支持する支承１０の新規支承１６への取り替えを行うことで機能回復を図ることができると共に、支承周りの補強を実施することができる。 As described above, the present embodiment can provide the same effects as those of the embodiment shown in FIGS. 1 to 14, and the outer ends of the outer main girders 4 and 6 are connected to the cross beam of the steel pier 1. It is possible to support each new girder bracket 39 newly installed on the bridge axial direction surface 3 via the new support 16 and also to the girder bracket 9b in which the end of the middle main girder 5 is reinforced via the new support 16. Because it can be supported, the function can be restored by replacing the bearing 10 that supports the loads of the main girders 4, 5 and 6 with the new bearing 16, and reinforcement around the bearing can be performed. Can do.

図１５乃至図２１（イ）（ロ）（ハ）の実施の形態、及び、図２２乃至図３０（イ）（ロ）（ハ）の実施の形態においては、いずれも、鋼製橋脚１の横梁３の各橋軸方向面に設けてある各桁受ブラケット９ａ，９ｂ，９ｃのうち、中主桁５に対応する既設の桁受ブラケット９ｂについて、桁受ブラケット補強部材３８による補強を施した後、該補強された既設の桁受ブラケット９ｂの上側に、別途補強された中主桁５の桁端を、新規支承１６を介して支持させるようにしてあるが、各外主桁４，６を直接又はアウトリガーを介してジャッキアップすると共に、一方の端横桁８ａをジャッキアップしたとき、又は、上記各外主桁４，６を上記と同様にジャッキアップした状態で且つ取り替えられた他方の新設の端横桁２１ｂをジャッキアップしたときに、上記各主桁４，５，６の荷重が作用しなくなっている状態の上記中主桁５に対応する既設の桁受ブラケット９ｂを、新規の桁受ブラケットに取り替えるようにしてもよい。 15 to 21 (a) (b) (c) and the embodiment of FIGS. 22 to 30 (b), (b), and (c), all of the steel pier 1 Of the girder brackets 9a, 9b, 9c provided on each bridge axial direction surface of the cross beam 3, the existing girder bracket 9b corresponding to the middle main girder 5 is reinforced by the girder bracket reinforcing member 38. After that, the end of the middle main girder 5 reinforced separately is supported on the upper side of the reinforced existing girder bracket 9b through the new support 16, but each outer main girder 4 and 6 is supported. Is jacked up directly or via an outrigger, and when one end cross beam 8a is jacked up, or the other main girders 4 and 6 are jacked up in the same manner as described above and the other one replaced. Jack up the new end girder 21b Sometimes, the existing girder bracket 9b corresponding to the middle main girder 5 in a state where the loads of the main girder 4, 5, 6 are not applied may be replaced with a new girder bracket. .

すなわち、図３１乃至図３４（イ）（ロ）は本発明の実施の更に他の形態として、上記したように中主桁５用の既設の桁受ブラケット９ｂの新規桁受ブラケットへの取り替えを実施する場合の適用例を示すもので、たとえば、図３１に手順のフローを示すように、図２２乃至図３０（イ）（ロ）（ハ）の実施の形態と同様の構成において、図２２のステップＢ１３（ＳＢ１３）までの手順を終えることで、図２５（ロ）（ハ）及び図２７（イ）（ロ）に示したように、既設の各端横桁８ａ，８ｂの新設の端横桁２１ａ，２１ｂへ取り替えを行った後、図３２（イ）に示す如く、各外主桁４，６に仮設したアウトリガー４０と他方の新設の端横桁２１ｂをジャッキアップした状態のままで、鋼製橋脚１の横梁３の各橋軸方向面に中主桁５に対応させて設けてある桁受ブラケット９ｂを撤去する（ステップＢ１７：ＳＢ１７）。 That is, FIGS. 31 to 34 (a) and (b) show, as another embodiment of the present invention, replacement of the existing girder bracket 9b for the middle main girder 5 with a new girder bracket as described above. An application example in the case of implementation is shown. For example, as shown in the flow of the procedure in FIG. 31, in the same configuration as the embodiment of FIGS. 22 to 30 (A), (B), and (C), FIG. By completing the procedure up to step B13 (SB13), as shown in FIGS. 25 (b) (c) and 27 (b) (b), the newly installed ends of the respective end cross beams 8a, 8b are provided. After the replacement to the horizontal beams 21a and 21b, as shown in FIG. 32 (a), the outriggers 40 temporarily installed in the outer main beams 4 and 6 and the other newly installed end horizontal beam 21b remain jacked up. Corresponding to the main main girder 5 on each bridge axial direction surface of the cross beam 3 of the steel pier 1 Thereby to remove the Keta受 bracket 9b which is provided (step B17: SB17).

次いで、図３２（ロ）に示す如く、上記鋼製橋脚１の横梁３の各橋軸方向面における上記中主桁５用の既設の桁受ブラケット９ｂの撤去部分に、中主桁５用の新規の桁受ブラケット４４を設ける。この際、該中主桁５用の新規桁受ブラケット４４を補強するために、該新規桁受ブラケット４４を、第１及び第２の各端横桁ジャッキアップ用受台１９ａ，１９ｂに一体に取り付けるようにしてある（ステップＢ１８：ＳＢ１８）。 Next, as shown in FIG. 32 (b), the removal portion of the existing girder bracket 9b for the middle main girder 5 on each bridge axial direction surface of the cross beam 3 of the steel pier 1 is attached to the middle main girder 5 A new girder bracket 44 is provided. At this time, in order to reinforce the new girder bracket 44 for the middle main girder 5, the new girder bracket 44 is integrated with the first and second end lateral girder jack-up cradles 19a and 19b. They are attached (step B18: SB18).

その後、図３３（イ）（ロ）に示す如く、上記新設された中主桁５支持用の新規桁受ブラケット４４の上側と、上記鋼製橋脚１の横梁３の各橋軸方向面に各外主桁４，６に対応させて設けてある各外主桁４，６支持用の新規桁受ブラケット３９の上側に、それぞれ新規の支承１６を設けた後、各アウトリガー４０と新設の他方の端横桁２１ｂをジャッキアップしている各ジャッキアップ用受台４２上のジャッキ４３ａ，４３ｂと第２の端横桁ジャッキアップ用受台１９ｂ上のジャッキ４３ｄをジャッキダウンすることで、上記各新規支承１６の上側に、上記中主桁５における切欠き部７ａの上側の桁端と、上記各外主桁４，６における新たに設けた切欠き部１８の上側の桁端をそれぞれ載置させて、上記中主桁５及び各外主桁４，６の荷重を、上記各新規支承１６と、それぞれ対応する各新規桁受ブラケット４４及び３９を介して上記鋼製橋脚１の横梁３に伝えて受けさせるようにする（ステップＢ１９：ＳＢ１９）。 After that, as shown in FIGS. 33 (a) and (b), the upper side of the newly installed new girder bracket 44 for supporting the middle main girder 5 and each bridge axial direction surface of the cross beam 3 of the steel pier 1 are respectively shown. After providing a new support 16 on the upper side of the new girder bracket 39 for supporting the outer main girders 4 and 6 provided corresponding to the outer main girders 4 and 6, respectively, each of the outriggers 40 and the other newly installed By jacking down jacks 43a and 43b on each jack-up receiving base 42 jacking up the end cross-girder 21b and jack 43d on the second end cross-girder jack-up receiving base 19b, the above-mentioned new On the upper side of the support 16, the upper end of the notch 7 a in the middle main girder 5 and the upper end of the newly provided notch 18 in each of the outer main girders 4, 6 are mounted. The load on the middle main girder 5 and the outer main girder 4 and 6 And said each new bearing 16, respectively, via each new Keta受 brackets 44 and 39 corresponding to like undergo tell crossbeam 3 above steel pier 1 (step B19: SB19).

上記のようにして中主桁５と各外主桁４，６の荷重を、各新規桁受ブラケット４４と３９を介して上記横梁３に支持させた後は、上記各アウトリガー４０及び各仮設横桁４１及び残りの各ジャッキ４３ａ，４３ｂ，４３ｄをそれぞれ撤去して（ステップＢ２０：ＳＢ２０）、端横桁取替作業、及び、支承取替作業を終了する。 After the loads of the middle main girder 5 and the outer main girders 4 and 6 are supported on the horizontal beam 3 via the new girder brackets 44 and 39 as described above, the outriggers 40 and the temporary horizontal beams are arranged. The girder 41 and the remaining jacks 43a, 43b, 43d are respectively removed (step B20: SB20), and the end cross girder replacement work and the bearing replacement work are finished.

これにより、図３４（イ）（ロ）に示すように、各主桁４と５及び各主桁５と６の桁端縁部同士が取り替えられた新設の端横桁２１ａ，２１ｂにより連結され、且つ上記各外主桁４，６の新たに切欠き部１８を設けた桁端と、上記中主桁５の補強された切欠き部７ａが設けてある桁端とを、鋼製橋脚１の横梁３の橋軸方向面における下部所要個所に設けた対応する新規桁受ブラケット３９と４４の上側に新規支承１６を介してそれぞれ支持させ、更に、上記既設の各端横桁８ａ，８ｂを支持していた既設の各桁受ブラケット９ａ，９ｃが撤去された構成を有するＩ桁橋が形成されるようになる。なお、本実施の形態では、上記したように中主桁５支持用の新規桁受ブラケット４４を、第１及び第２の各端横桁ジャッキアップ用受台１９ａ，１９ｂに一体に取り付けるようにしてあることから、該各上記端横桁ジャッキアップ用受台１９ａ，１９ｂは残置するようにしてある。 Thus, as shown in FIGS. 34 (a) and (b), the main girder 4 and 5 and the girder edge portions of the main girder 5 and 6 are connected by the newly-installed end cross beams 21a and 21b. Further, the end of the girder provided with the notch 18 of each of the outer main girders 4 and 6 and the end of the girder provided with the reinforced notch 7a of the middle main girder 5 are connected to the steel pier 1. Are supported on the upper side of the corresponding new girder brackets 39 and 44 provided at the lower required positions on the bridge axial direction surface of the horizontal beam 3 via the new support 16, and the above-mentioned existing end girders 8a and 8b are respectively supported. An I-girder bridge having a configuration in which the existing girder brackets 9a and 9c that have been supported are removed is formed. In the present embodiment, as described above, the new girder bracket 44 for supporting the middle main girder 5 is integrally attached to the first and second end cross girder jack-up cradles 19a and 19b. Therefore, each of the end cross girder jack-up receiving bases 19a, 19b is left behind.

その他、図２３乃至３０（イ）（ロ）（ハ）に示したものと同一のものには同一の符号が付してある。 In addition, the same components as those shown in FIGS. 23 to 30 (a), (b), and (c) are denoted by the same reference numerals.

このように、本実施の形態によれば、図２２乃至図３０（イ）（ロ）（ハ）の実施の形態と同様の効果に加えて、中主桁５の桁端を、鋼製橋脚１の横梁３の橋軸方向面に新設する中主桁５支持用の新規桁受ブラケット４４に新規支承１６を介して支持させることで、該中主桁５を支持する支承回りの補強を実施することができる。 Thus, according to the present embodiment, in addition to the same effects as those of the embodiments of FIGS. 22 to 30 (a), (b), and (c), the end of the middle main girder 5 is connected to the steel pier. The support for supporting the middle main girder 5 is reinforced by supporting the middle main girder 5 on the new girder bracket 44 for supporting the middle main girder 5 newly installed on the surface of the cross beam 3 of the horizontal beam 1. can do.

なお、上記横梁３の橋軸方向面に設けてある中主桁５支持用の既設の桁受ブラケット９ｂの新規桁受ブラケット４４への取り替えは、ステップＢ６（ＳＢ６）で図２４に示したと同様に、各外主桁４，６に設けたアウトリガー４０と既設の一方の端横桁８ａをジャッキアップすることにより、各主桁４，５，６の荷重を、上記既設の中主桁５支持用の桁受ブラケット９ｂより抜いた以降であれば、ステップＢ７（ＳＢ７）の前、あるいは、該ステップＢ７（ＳＢ７）からステップＢ１３（ＳＢ１３）までの間の任意のステップ間で行うようにしてもよい。 The replacement of the existing girder bracket 9b for supporting the middle main girder 5 provided on the bridge axis direction surface of the horizontal beam 3 with the new girder bracket 44 is the same as that shown in FIG. 24 in step B6 (SB6). Further, the outriggers 40 provided on the outer main girders 4 and 6 and the existing one end lateral girder 8a are jacked up to support the load of the main girders 4, 5 and 6 on the existing middle main girder 5 above. If it is after it has been removed from the girder support bracket 9b, it may be performed before step B7 (SB7) or between arbitrary steps between step B7 (SB7) and step B13 (SB13). Good.

又、上記中主桁５支持用の新規桁受ブラケット４４は、鋼製橋脚１の横梁３の橋軸方向面における既設の中主桁５支持用の桁受ブラケット９ｂの撤去部分を補強する等して、該部分に単独で取り付けて各主桁４，５，６より作用する荷重を支持するための十分な強度を得ることができれば、第１及び第２の各端横桁ジャッキアップ用受台１９ａ，１９ｂとは分離させた状態で設けるようにしてもよい。よって、この場合は、上記中主桁５を該中主桁５支持用の新規桁受ブラケット４４に支持させた後に各主桁４，５，６の荷重の支持には関与しなくなる上記第１及び第２の各端横桁ジャッキアップ用受台１９ａ，１９ｂは、図３４に示したステップＢ２０で撤去するようにすればよい。 The new girder bracket 44 for supporting the middle main girder 5 reinforces the removed portion of the girder bracket 9b for supporting the middle main girder 5 on the surface of the bridge 3 in the direction of the bridge axis of the steel pier 1. If the sufficient strength to support the load acting from the main girders 4, 5 and 6 can be obtained by attaching to the part alone, the first and second end cross girder jack-up receptacles are provided. You may make it provide in the state isolate | separated from the bases 19a and 19b. Therefore, in this case, after the middle main girder 5 is supported by the new girder receiving bracket 44 for supporting the middle main girder 5, the first first will not be involved in supporting the loads of the main girders 4, 5 and 6. The second end cross beam jack-up cradle 19a, 19b may be removed in step B20 shown in FIG.

なお、図示してないが、図１５乃至図２１の実施の形態においても、図１におけるステップＡ３（ＳＡ３）と同様のステップＡ３（ＳＡ３）、すなわち、図３に示したように各外主桁と既設の一方の端横桁８ａをジャッキアップすることにより、各主桁４，５，６の荷重を、上記既設の中主桁５支持用の桁受ブラケット９ｂより抜いた以降であれば、ステップＡ１５（ＳＡ１５）で図２０に示したように新設の各端横桁２１ａ，２１ｂをジャッキダウンして上記各主桁４，５，６からの荷重が中主桁５支持用の桁受ブラケットに作用するまでの任意の時点で、鋼製橋脚１の横梁３の橋軸方向面に設けてある中主桁５支持用の既設の桁受ブラケット９ｂの新規桁受ブラケットへの取り替えを行うようにしてもよい。 Although not shown, also in the embodiment of FIGS. 15 to 21, step A3 (SA3) similar to step A3 (SA3) in FIG. 1, that is, each outer main girder as shown in FIG. If the load of each main girder 4, 5, 6 is removed from the existing girder bracket 9 b for supporting the middle main girder 5 by jacking up the existing one end cross girder 8 a, In step A15 (SA15), as shown in FIG. 20, the newly installed end cross girders 21a, 21b are jacked down so that the load from the main girders 4, 5, 6 is supported by the middle main girder 5 support bracket. At any time until it acts on the bridge, the existing girder bracket 9b for supporting the middle main girder 5 provided on the surface of the bridge 3 in the cross beam direction of the steel pier 1 is replaced with a new girder bracket. It may be.

更には、図１乃至図１４の実施の形態において、ステップＡ３（ＳＡ３）で図３に示したように各外主桁と既設の一方の端横桁８ａをジャッキアップすることにより、各主桁４，５，６の荷重を、上記既設の中主桁５支持用の桁受ブラケット９ｂより抜いた後、ステップＡ１０（ＳＡ１０）で図７に示したように、各外主桁４，６と新設の他方の端横桁２１ｂのジャッキダウンを行って、各主桁４，５，６からの荷重が中主桁５支持用の桁受ブラケットに作用するまでの任意の時点で、鋼製橋脚１の横梁３の橋軸方向面に設けてある中主桁５支持用の既設の桁受ブラケット９ｂの新規桁受ブラケットへの取り替えを行うようにしてもよい。 Furthermore, in the embodiment shown in FIGS. 1 to 14, each main girder is jacked up in step A3 (SA3) as shown in FIG. 3 to each outer main girder and the existing one end girder 8a. After the loads 4, 5 and 6 are removed from the above-mentioned existing girder bracket 9b for supporting the middle main girder 5, as shown in FIG. 7 in step A10 (SA10), each outer main girder 4, 6 and Steel bridge pier at any point in time until the load from each main girder 4, 5, 6 acts on the girder bracket for supporting the middle main girder 5 by jacking down the newly installed other end girder 21 b The existing girder bracket 9b for supporting the middle main girder 5 provided on the surface in the bridge axis direction of the one horizontal beam 3 may be replaced with a new girder bracket.

なお、本発明は上記実施の形態のみに限定されるものではなく、既設の端横桁８ａ，８ｂの新設の端横桁２１ａ，２１ｂへの取り替え順序は逆にしてもよい。 In addition, this invention is not limited only to the said embodiment, You may reverse the replacement order of the existing end cross beam 8a, 8b to the new end cross beam 21a, 21b.

図１乃至図１４の実施の形態、及び、図１５乃至図２１（イ）（ロ）（ハ）の実施の形態で用いる第２の端横桁ジャッキアップ用受台１９ｂは、中主桁５と他方の外主桁６との間で行う既設の他方の端横桁８ｂの撤去作業、及び、新設の他方の端横桁２１ｂの取り付け作業に支障を来さなければ、ステップＡ２（ＳＡ２）で横梁３の各橋軸方向面の所定個所へ第１の端横桁ジャッキアップ用受台１９ａを設置するときに、同時に設置を行うようにしてもよい。 The second end cross girder jack-up cradle 19b used in the embodiment of FIGS. 1 to 14 and the embodiments of FIGS. Step A2 (SA2) if there is no problem in the removal work of the existing other end cross beam 8b and the installation work of the newly installed other end cross beam 21b performed between the outer main beam 6 and the other outer main beam 6. When the first end cross girder jack-up cradle 19a is installed at a predetermined location on each bridge axial direction surface of the cross beam 3, the installation may be performed at the same time.

又、第１の端横桁ジャッキアップ用受台１９ａは、一方の外主桁４と中主桁５との間で行う既設の一方の端横桁８ａの撤去作業、及び、新設の一方の端横桁２１ａの取り付け作業に該第１の端横桁ジャッキアップ用受台１９ａが邪魔になる場合は、該作業の間、撤去するようにしてもよい。 In addition, the first end cross girder jack-up cradle 19a is used to remove the existing one end cross girder 8a between the outer main girder 4 and the middle main girder 5 and If the first end cross beam jack-up cradle 19a is in the way of attaching the end cross beam 21a, it may be removed during the operation.

図１５乃至図２１（イ）（ロ）（ハ）の実施の形態におけるステップＡ４ａ（ＳＡ４ａ）とステップＡ８ａ（ＳＡ８ａ）で行う各既設の端横桁８ａ，８ｂを支持していた既設の桁受ブラケット９ａ，９ｃの撤去は、ステップＡ３（ＳＡ３）における各主桁４，５，６のジャッキアップ操作の後、ステップＡ１５（ＳＡ１５）で各主桁４，５，６の桁端を新規支承１６の上に載置するまでの間であれば、任意の時点で行うようにしてもよい。 The existing girder support supporting each of the existing end cross beams 8a and 8b performed in step A4a (SA4a) and step A8a (SA8a) in the embodiment of FIGS. The brackets 9a and 9c are removed by jacking up the main girders 4, 5 and 6 in step A3 (SA3) and then attaching the end of the main girders 4, 5 and 6 to the new support 16 in step A15 (SA15). It may be performed at an arbitrary time as long as it is until it is placed on.

又、図１５乃至図２１（イ）（ロ）（ハ）の実施の形態では、各既設の端横桁８ａ，８ｂを各新設の端横桁２１ａ，２１ｂにそれぞれ取り替えた後、該各新設の端横桁２１ａ，２１ｂのジャッキアップによる各主桁４，５，６の荷重の支持を行った状態で、ステップＡ１３（ＳＡ１３）で各外主桁ジャッキアップ用受台１７を撤去してから、ステップＡ１４（ＳＡ１４）で各外主桁支点用ブラケット３５を新たに設けるようにしているが、上記各外主桁ジャッキアップ用受台１７を、各外主桁４，６を新規支承１６を介して支承するための上記各外主桁支点用ブラケット３５を兼ねる機能を有するものとしてもよい。この場合は、ステップＡ１３（ＳＡ１３）では、各外主桁ジャッキアップ用受台１７は残したまま、該各外主桁ジャッキアップ用受台１７上のジャッキ２０ａ，２０ｂのみを撤去するようにした後、ステップＡ１４（ＳＡ１４）で、上記各外主桁ジャッキアップ用受台１７上に新規支承１６を設置するようにすればよい。 Further, in the embodiment shown in FIGS. 15 to 21 (a), (b), and (c), each of the existing end cross beams 8a and 8b is replaced with each of the newly installed end cross beams 21a and 21b. After removing the outer main girder jack-up cradle 17 in step A13 (SA13) in a state where the loads of the main girder 4, 5, 6 are supported by jack-up of the end horizontal girders 21a, 21b. In step A14 (SA14), the outer main girder fulcrum brackets 35 are newly provided. However, the outer main girder jack-up receiving base 17 is replaced with the outer main girder 4 and 6 and the new support 16 is mounted. It is good also as what has the function which doubles as the bracket 35 for each said outer main girder fulcrum for supporting via. In this case, in step A13 (SA13), only the jacks 20a and 20b on the outer main girder jack-up cradle 17 are removed while the outer main girder jack-up cradle 17 remains. Thereafter, in step A14 (SA14), the new support 16 may be installed on each of the outer main girder jack-up receiving bases 17.

図２２乃至図３０（イ）（ロ）（ハ）の実施の形態では、各主桁４，５，６の荷重の３点の支承個所のうち、中主桁５の桁端以外の２点の支承個所を、既設の各端横桁８ａ，８ｂより各外主桁４，６の桁端へ変更するものとして示したが、支承個所の変更が必要ない場合は、既設の各桁受ブラケット９ａと９ｃを撤去することなく、該各桁受ブラケット９ａ，９ｂを適宜補強してから、該各既設の桁受ブラケット９ａ，９ｃ上に、取り替えられた新設の端横桁２１ａ，２１ｂを、新規支承１６を介して載置して支持させるようにしてもよい。 22 to 30 (a), (b), and (c), two points other than the end of the middle main girder 5 out of the three bearing points of the loads of the main girder 4, 5, 6 are used. Is shown as changing from the existing end girder 8a, 8b to the end of each outer main girder 4, 6, but if there is no need to change the support location, each existing girder bracket Without removing 9a and 9c, each girder bracket 9a, 9b is appropriately reinforced, and the replaced new end girder 21a, 21b is placed on each existing girder bracket 9a, 9c. You may make it mount and support via the new support 16. FIG.

桁端がフルウェブの外主桁４，６と、桁端に切欠き部７を有する中主桁５の隣接する桁端縁部同士を橋幅方向に延びる横桁で接続すると共に、上記各主桁４，５，６の荷重を、各主桁４と５，各主桁５と６の桁端縁部同士を接続している各支承用の横桁の位置で支承するようにしてある形式のＩ桁橋であれば、中主桁５を複数本具備した多主Ｉ桁橋における上記各支承用の横桁の取り替えにも適用してよい。更には、首都高速道路の高架橋以外のＩ桁橋にも適用してよい。 The girder ends are connected to the outer main girders 4 and 6 of the full web and the adjacent girder edge edges of the middle main girder 5 having the notch portion 7 at the girder ends with the horizontal girder extending in the bridge width direction. The loads of the main girders 4, 5 and 6 are supported at the positions of the horizontal girders for each support which connect the end edges of the main girders 4 and 5 and the main girders 5 and 6. If it is a type I girder bridge, it may be applied to the replacement of the above-mentioned horizontal girder for a multi-main I girder bridge having a plurality of middle main girder 5. Furthermore, the present invention may be applied to I-girder bridges other than viaducts on the Metropolitan Expressway.

更に又、主桁の桁端縁部同士を接続し、且つ主桁の荷重を支承する横桁を備えていれば、Ｉ桁橋以外のいかなる形式の桁橋にも適用してよい。 Furthermore, the present invention may be applied to any type of girder bridge other than the I-girder bridge as long as the girder edges of the main girder are connected to each other and a horizontal girder for supporting the load of the main girder is provided.

その他本発明の要旨を逸脱しない範囲内で種々変更を加え得ることは勿論である。 Of course, various modifications can be made without departing from the scope of the present invention.

１鋼製橋脚（橋脚）
３横梁
４外主桁
５中主桁
６外主桁
８ａ，８ｂ端横桁（支承用の横桁）
９ａ，９ｂ，９ｃ桁受ブラケット
１０支承
１６新規支承
２１ａ，２１ｂ新設の端横桁（新設の横桁）
３５支点用ブラケット
３９新規桁受ブラケット
４４新規桁受ブラケット 1 Steel pier (pier)
3 Cross beam 4 Outer main girder 5 Middle main girder 6 Outer main girder 8a, 8b End horizontal girder (horizontal girder for support)
9a, 9b, 9c Girder brackets 10 Bearings 16 New bearings 21a, 21b Newly installed end cross beams (new cross beams)
35 Bracket for fulcrum 39 New girder bracket 44 New girder bracket

Claims

橋幅方向両端部に位置する各外主桁と橋幅方向の内側に位置する中主桁とを、橋脚の横梁と平行に橋幅方向に延びる別々の支承用の横桁で接続し、且つ上記橋脚の横梁の橋軸方向の側面に突設した桁受ブラケットに、上記中主桁の桁端と、上記各支承用の横桁の橋幅方向外側端部寄り個所を、それぞれ支承を介して支持させてなる桁橋における上記各外主桁をジャッキアップすると共に、上記各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップした状態で、上記各支承用の横桁のうちの他方の外主桁側の横桁を、新しい横桁に取り替え、次いで、上記各外主桁をジャッキアップした状態で、上記取り替えられた他方の新設の横桁をジャッキアップし、上記支承用の一方の外主桁側の横桁をジャッキダウンしてから、該ジャッキダウンした一方の横桁を新しい横桁に取り替えるようにすることを特徴とする横桁取替方法。 Each outer main girder located at both ends of the bridge width direction and the middle main girder located inside the bridge width direction are connected by separate support cross beams extending in the bridge width direction in parallel with the transverse beam of the bridge pier, and The girder bracket projecting on the side of the bridge pier's cross beam in the direction of the bridge axis is connected to the end of the middle main girder and the position near the outer edge of the bridge girder in the width direction of the bridge. Jacking up each outer main girder in the girder bridge that is supported by the jack, and jacking up one outer main girder side of the above-mentioned horizontal girder for each support, Replace the horizontal beam on the other outer main beam side of the horizontal beam with a new horizontal beam, and then jack up the other newly installed horizontal beam with the other outer main beam jacked up. Jacking down the cross beam on one outer main beam side for the above-mentioned support, Cross beams replacement method characterized by so replace one crossbeam which is in to the new crossbeam.

各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、各支承用の横桁の橋幅方向外側端部寄り個所の支持に用いられていた各桁受ブラケットを撤去するようにし、更に、支承用の他方及び一方の横桁が新設の横桁に取り替えられた状態で、各外主桁の桁端を、該各外主桁の桁端直下位置にそれぞれ新設した各ブラケットに新規支承を介して載置すると共に、中主桁の桁端を、対応する桁受ブラケット上に既設の支承に取り替えて設けた新規支承を介して載置するようにする請求項１記載の横桁取替方法。 Each outer main girder was jacked up and replaced when one of the horizontal girder for each support was jacked up, or when each outer main girder was jacked up When the other newly installed girder is jacked up, it is used to support the part near the outer edge of the bridge width direction of each girder support bracket among the girder brackets protruding from the girder beam. In addition, each girder bracket is removed, and the end of each outer main girder is connected to the girder of each outer main girder in the state that the other and one cross girder for support are replaced with new ones. Place it on each newly installed bracket directly under the edge via a new support, and place the end of the middle main girder on the corresponding girder bracket by replacing it with an existing support. The method for replacing a cross girder according to claim 1.

各外主桁をジャッキアップすると共に、各支承用の横桁のうちの一方の外主桁側の横桁をジャッキアップしたとき、又は、各外主桁をジャッキアップした状態で、取り替えられた他方の新設の横桁をジャッキアップしたときに、橋脚の横梁に突設してある各桁受ブラケットのうち、中主桁の桁端の支持に用いられていた既設の桁受ブラケットを、新たな桁受ブラケットに取り替えて、中主桁の桁端を、上記取り替えた新設の桁受ブラケット上に新規支承を介して載置するようにする請求項１又は２記載の横桁取替方法。 Each outer main girder was jacked up and replaced when one of the horizontal girder for each support was jacked up, or when each outer main girder was jacked up When the other newly installed girder is jacked up, the existing girder brackets used to support the girder ends of the middle main girder are replaced with new ones. 3. A method for replacing a girder according to claim 1 or 2, wherein a girder end of the middle main girder is replaced with a new girder bracket and placed on the replaced girder bracket newly installed via a new support.