US1976188A - Arcuate truss - Google Patents

Description

n. NQTAWA ARCUATE TRUSS Filed NGVn l, 1953 2 Sheets-Sheet 2 Patented Oct. 9, 1934 ABCUATE TRUSS Ichiro Nozawa, Tsukishima, Kyobashi-Ku,

Tokyo, Japan Application November 1, 1933, Serial No. 696,275 In Japan December 26, 1932 3 Claims. (Cl. 1118-1) My invention relates to improvements in trusses and more particularly in structure of arcuate By arcuate truss, I mean truss the vertical section of which takes any of such shapes :is parabolic, semi-circular and other convexed curvatures of substantially continuous nature.

It is well recognized in the art that parabola'. is the ideal shape or the vertical section of a truss with vertical loads imposed thereon, by virtue ci the fact that it eliminates bending moment 'throughout the section. A real parabola, however, is hardly obtained in a steel truss, and in practice, a convexed curve of an approximate parabola, semi-circle or equivalent arcute form is utilized in place of real parabola.

It is also well known that a structure is very strong against twisting stress, if it includes diegonal members. Consequently, when the arcuate truss above-speciiied is mainly made of di` agonal members, it may have maximum mechanical strength with least amount of material.

One object of my invention is to obtain arcuate trusses of the above-mentioned nature with simple and economical construction and with least .number of kinds of component elements.

Another object of my invention is to provide arcuate trusses which are readily assembled and disassembled, and easy in renewal of component elements.

A further object of my invention is to provide component elements for arcuate trusses which are readily made oi' comercial angle bars, I- bars, channel bars, etc., and of relatively short dimensions and light weight adapted for easy and prompt assembling and disassembling works, transportation, storing, etc.

A further object of my invention is to provide arcuate. trusses composed of a large number of light unit-elements having substantially uni- J iorm shape 'and length, the trusses still having adequate mechanical strength particularly against vertical load and twisting stress.

There are still other objects and particularities of my invention, which, together with the construction thereof, will be made clear in the following descriptions in connection with the accompanying drawings, wherein:-

Fig. 1 is a perspective view showing one embodiment of my invention, the back half being shown by dotted lines for clearness.

Fig. 2 is an elevational view of another embodiment of my invention, the front half being partly broken away and the vertical section along the centre being shown by dotted lines.

Fig. 3 is an extended elevational view of one portion of the arcuate truss shown in Fig. 1 or 2.

Figs. 4 and 5 show two examples oi the unitelement used in the structure.

Figs. 6 and 7 are fragmental perspective views 60 of the arcuate truss respectively composed of the unit-elements shown in Figs. 4 and 5.

Fig. 8 is a fragmental perspective view of the lower portion of the arcuate truss shown in Fig. l or 2.

Fig. 9 is an elevational view of the joint structure shown in Fig. 8.

Fig. 1G shows an element shown in Figs. 8 and 9.

Referring now to Fig. 1, the arcuate truss embodying my invention has a'substantially semicylindrical overall form, while in Fig. 2, the truss has a substantially semi-spherical form. It may take any other form, as far as the vertical section thereof has a substantially continuous convexed curvature. The trusses shown in Figs. 1 and 2 respectively have a substantially semi-circular vertical section.

The 'truss is composed of a large number of unit-elements l disposed in inclination to the horizon or ground G alternately in opposite di- 8 rections, and forming a network as a whole. Each element 1 has a pair of joint plates 2 secured to both sides of the element midway of its length, and an aligned pair of other unit-elements 1 are secured to said joint plates 2 at the ends of the 85 latters or incident unit-elements, thus forming a substantially X-shaped structure, as clearly shown in Fig. 3. If the angle a, which is embraced between the adjacent unit-elements 1 formingV each X-shaped structure, is denite throughout 90 the truss, the truss will have a substantially semioylindrical formas shown in Fig. 1, while the truss will have a substantially semi-spherical form if the angle a is gradually varied along the vertical periphery, as shown in Fig. 2. 95

Each element 1 comprises a pair of spaced and parallel side bars 3 and 4 which are connected with each other by a plurality of connecting members 5 and 6, some of them being arranged perpendicular to the side bars as shown by 6, while 100 the others 5 being arranged diagonally. They are secured to the side bars' at the endsby suitable means such as riveting. Welding may also be utilized. The perpendicular connecting member 6 may be disposed at each end of the element 1 as shown in Fig. 4, or at the centre of the element l as shown in Fig. 5. The side members 3 and 4 may conveniently be made of commercial angle bars, and are bent at the centre thereof to embrace a suitable and equal angle b inside the 110 truss, respectively. The angle b determines the radius of curvature of vertical section of the truss. It must also be observed that the lower or inner side bar 4 is slightly shorter in length than the upper or outer side bar 3 for adaptation to the curvature.

The joint plates 2 are secured to the side bars 3 and 4 respectively by rivets 7 for example, and provided with a plurality of perforations 8 which register with corresponding perforations in the adjacent ends of the two unit-elements 1 incident to the joint, and through which perforations securing means are inserted to secure the incident unit-elements to the joint plate 2. As the securing means, rivets 9 may be used as shown in Fig. 6, or bolts and nuts 10 may be used as shown in Fig. 7. If the bolts and nuts l0 are used for securing the incident unit-elements to the joint plates 2, the truss may be easily disassembled.

The joint structure shown in Fig. 6, wherein unit-elements as shown in Fig. 4 are used, and

that shown in Fig. 7, wherein unit-elements as shown in Fig. 5 are used, are replaceable with each other. They merely differ from each other in that two perpendicular connecting members 6 act as supporting pillars for the pair of spaced joint plates 2 in the former, while in the latter a single member 6 acts for the' same purpose.

If desired, each of the side bars 3 and 4 may be made of two angle bars disposed in side-byside relation in order to insure the -mechanical strength of the truss, throughout or in one portion of the arcuate truss. In Figs. l and 2, the lower portions of the trusses are constructed of unit-elements 1 of such doubled nature, and the details thereof are shown in Figs. 8 to 10. In order to further strengthen the structure, horizontal connecting bars 11 may be disposed between adjacent joint plates 2 and suitably secured thereto at the ends. In such cases, the joint plates 2 must be so shaped that they have ample area. for riveting or bolting the horizontal connecting bars 11 to the plates, as well as for the unit-elements l incident to the joint.

It will be obvious that the alternate unit-elements 1" forming the border portions of the truss must have a half length of the normal unit-element 1 or 1', in order to obtain linear border lines. Such shorter unit-elements 1" may conveniently be obtained by cutting the normal unitelement 1 as shown in Fig. 4 into two at the centre thereof or at the vertex of the angle b.

In practice, the unit-elements 1 are say 4 metres in length and 0.6 metre in width, and they may be easily transported and handled. Since all the unit-elements extend diagonally and secured with each other forming a network, the truss can withstand considerable twisting stress. The truss also has arcuate Vertical section, and the mechanical strength thereof against vertical stress or load can be maximum with the least amount of material.

I claim as my invention:

l. An arcuate metal structure comprising a plurality of unit-elements inclined alternately in opposite directions, each of Asaid unit-elements comprising a pair of parallel side bars which are spaced apart transversely of the structure and slightly different in length and bent inwardly about the centre of their lengths, a plurality of connecting members for said pair of side bars, and a pair of joint plates respectively secured to said pair of side bars at the centre thereof, and each unit-element being connected by its centrally arranged joint plates with the ends of two adjacent and aligned unit-elements in such a manner that the arcuate structure so formed.

presents in front elevation diamond-shaped spaces between the each unit-element.

2. An arcuate metal structure according to claim 1, in which some of said connecting members are disposed perpendicular to said side bars while the others are disposed diagonally to said side bars.

3. An arcuate metal structure comprising a plurality of iirst unit-elements and a plurality of second unit-elements the length of which is a half of said rst unit-elements, all of said unitelements being inclined in opposite directions, each of said first unit-elements comprising a pair of parallel side bars which are spaced apart transversely of the structure and slightly dilerent in length and bent inwardly about the centre of their lengths, a plurality of connecting members for said pair of side bars, and a pair of joint plates respectively secured to said pair of side bars at the centre thereof, while each of said second unit-elements comprising a pair of parallel side bars which are spaced apart transversely of the structure and slightly different in length and a plurality of connecting members therefor, and each of said first unit-elements being connected by its centrally arranged joint plates with the ends of two adjacent and aligned unit-elements in such a manner that the arcuate structure so formed presents in front elevation diamond-shaped spaces between the each unitelement.

ICHIRO NOZAWA.

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