CN117947974B - Prestress reinforced wood roof truss - Google Patents
Prestress reinforced wood roof truss Download PDFInfo
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- CN117947974B CN117947974B CN202410345786.4A CN202410345786A CN117947974B CN 117947974 B CN117947974 B CN 117947974B CN 202410345786 A CN202410345786 A CN 202410345786A CN 117947974 B CN117947974 B CN 117947974B
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- 239000002023 wood Substances 0.000 title claims abstract description 69
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 14
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 229910000838 Al alloy Inorganic materials 0.000 claims description 4
- 210000001015 abdomen Anatomy 0.000 claims 2
- 230000002787 reinforcement Effects 0.000 abstract description 12
- 235000008708 Morus alba Nutrition 0.000 abstract 1
- 240000000249 Morus alba Species 0.000 abstract 1
- 238000004364 calculation method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0281—Repairing or restoring roofing or roof covering
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Mechanical Engineering (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
Abstract
The invention discloses a prestress reinforced wood roof truss, relates to the technical field of reinforcement engineering of traditional wood roof trusses, and aims to solve the problems that in the prior art, at least one of historic mulberry feel and high engineering cost of a building cannot be reserved in wood roof reinforcement. The wood roof truss comprises a reinforcing device; the reinforcing device comprises a lower chord prestress pull rod, a vertical web prestress pull rod and a prestress adjusting rod; the lower chord prestress pull rod is arranged along the lower chord; the vertical web prestress pull rod is arranged along the vertical web member; the linear expansion coefficient of the prestress adjusting rod is larger than that of the lower chord prestress pull rod, the prestress adjusting rod is arranged along the direction of the lower chord prestress pull rod, one end of the prestress adjusting rod is fixedly connected with one end of the lower chord prestress pull rod, and the other end of the prestress adjusting rod is fixedly connected with the other end of the lower chord prestress pull rod. The invention can be used for reinforcing the wood roof truss.
Description
Technical Field
The invention relates to the technical field of reinforcement engineering of traditional wood roof trusses, in particular to a prestress reinforced wood roof truss.
Background
The traditional wood roof truss exists in a large number in factory buildings, warehouses, auditoriums and civil houses, and a plurality of the buildings have historic sense and commemorative significance, so that the wood roof truss has high retention value.
The reinforcement technology of the building wood roof truss is still at the stage of repairing the partial damaged components and replacing the components with serious damage at present, and the requirement of increasing the load bearing capacity of the roof load can only be removed for rework. The method can not only keep the history of the building, but also cause the waste of materials and high engineering cost.
Disclosure of Invention
In view of the above, the present invention aims to provide a prestress reinforced wood roof truss, which is used for solving the problems that the wood roof reinforcement in the prior art cannot retain at least one of the historic cang sang feeling and the high engineering cost of the building.
The aim of the invention is mainly achieved by the following technical scheme.
The invention provides a prestress reinforced wood roof truss, which comprises an original roof truss and a reinforcing device;
The original roof truss comprises upper chords, lower chords and vertical web members, wherein the number of the upper chords is 2, the number of the lower chords is 1, the two upper chords and the 1 lower chords are connected to form a triangle, the upper end of the vertical web member is fixedly connected with the upper chords, and the lower end of the vertical web member is fixedly connected with one end of the lower chords;
The reinforcing device comprises a lower chord prestress pull rod, a vertical web prestress pull rod and a prestress adjusting rod;
The lower chord prestress pull rod is arranged along the lower chord member and is arranged at the lower part of the lower chord member, one end of the lower chord prestress pull rod is fixedly connected with the lower chord member, and the other end of the lower chord prestress pull rod is fixedly connected with the other end of the lower chord member;
The vertical web prestress pull rod is arranged along the vertical web member and is overlapped with the vertical web member, the upper end of the vertical web prestress pull rod is fixedly connected with the upper end of the vertical web member, and the lower end of the vertical web prestress pull rod is fixedly connected with the lower end of the vertical web member;
The linear expansion coefficient of the prestress adjusting rod is larger than that of the lower chord prestress pull rod, and the prestress adjusting rod is arranged along the direction of the lower chord prestress pull rod and is fixedly connected with the lower chord prestress pull rod;
The span of the original roof truss is 8-12 m, the span height is 2-4 m, the constant load of the roof is 8-13 KN/m, the live load of the roof is 1.5-3 KN/m, the prestress applied by the lower chord prestress pull rod is 45-55 KN, the prestress applied by the vertical web prestress pull rod is 7-15 KN, the prestress of the lower chord prestress pull rod is balanced by the lower chord member of the original roof truss, and the prestress of the vertical web prestress pull rod is balanced by the vertical web member of the wood roof truss.
Further, a stay bar is arranged between the lower chord prestress pull bar and the lower chord member, and the lower chord prestress pull bar is in close contact with the lower chord member through the stay bar.
Further, the stay bar comprises a hanging rod, a supporting cylinder, a supporting plate, a rotating handle, a first threaded rotating rod, a second threaded rotating rod, a first threaded sleeve, a second threaded sleeve, a first heightening rod and a second heightening rod;
the upper end of the supporting cylinder is provided with an opening, the hanging rod is arranged on the outer side of the supporting cylinder, and the supporting plate is arranged above the supporting cylinder;
The support cylinder is fixedly connected with the lower chord prestress pull rod;
One end of the rotating handle is rotationally connected with the upper end of the hanging rod, the lower end of the hanging rod is clamped with the lower surface of the lower chord prestress pull rod when snow load exists, one end of the first threaded rotating rod penetrates through one side of the supporting cylinder and is fixedly connected with the other end of the rotating handle, the other end of the first threaded rotating rod is fixedly connected with one end of the second threaded rotating rod, and the other end of the second threaded rotating rod is rotationally connected with the other side of the supporting cylinder;
The first threaded sleeve is sleeved on the outer wall of the first threaded rotating rod and is in threaded connection with the first threaded rotating rod, the second threaded sleeve is sleeved on the outer wall of the second threaded rotating rod and is in threaded connection with the second threaded rotating rod, and the threaded direction of the first threaded rotating rod is opposite to that of the second threaded rotating rod;
one end of the first heightening rod is rotationally connected with the first threaded sleeve, the other end of the first heightening rod is rotationally connected with the supporting plate, the other end of the second heightening rod is rotationally connected with the second threaded sleeve, and the other end of the second heightening rod is rotationally connected with the supporting plate;
when snow load is generated by snowing, the lower end of the hanging rod moves downwards to hang on the lower surface of the lower chord member, the hanging rod drives the first threaded rotating rod and the second threaded rotating rod to rotate through the rotating handle, so that the first threaded sleeve and the second threaded sleeve are mutually close to each other in the horizontal direction, the angle between the first heightening rod and the second heightening rod and the horizontal direction is driven to be increased, and the vertical heights of the first heightening rod and the second heightening rod are increased.
Further, the lower chord prestress pull rod supports part of the lower chord through the support rod to form an inverted arch.
Further, two ends of the prestress adjusting rod are fixedly connected with the lower chord prestress pull rod through lock clamps.
Further, the number of the prestress adjusting rods is two; one of the prestress adjusting rods is close to one end of the lower chord prestress pull rod, and the other prestress adjusting rod is close to the other end of the lower chord prestress pull rod.
Further, the length of the prestress adjusting rod is greater than or equal to 1m.
Further, the wood roof truss also comprises a U-shaped plate, and the two upper chords are fixedly connected through the U-shaped plate.
Further, the lower chord prestress pull rod is made of steel.
Further, the prestress adjusting rod is made of aluminum alloy.
Compared with the prior art, the invention can realize at least one of the following beneficial effects.
A) According to the pre-stress reinforced wood roof truss provided by the invention, the lower chord pre-stress pull rod and the vertical web pre-stress pull rod are additionally arranged on the basis of the original roof truss, the lower chord pre-stress pull rod is used for pre-stress reinforcing the lower chord, the vertical web is pre-stress reinforced through the vertical web pre-stress pull rod, and the pre-stress applied by the lower chord pre-stress pull rod and the vertical web is regulated, so that the tensile force applied by the lower chord and the vertical web is zero, further damage to the tensile force of the lower chord and the vertical web can be reduced or even avoided, the integral bearing capacity of the wood roof truss is improved on the premise that the original roof truss wood is not replaced or replaced as little as possible, and the potential safety hazard existing in the original roof truss is eliminated.
B) According to the wood roof truss reinforced by the prestress, the prestress adjusting rod is arranged, the linear expansion coefficient of the prestress adjusting rod is larger than that of the lower chord prestress pull rod, and the prestress adjusting rod does not apply prestress to the lower chord prestress pull rod when in summer by utilizing the characteristic of thermal expansion and cold contraction of the prestress adjusting rod, and the prestress adjusting rod contracts and applies prestress to the lower chord prestress pull rod when in winter, so that the prestress applied to the lower chord is increased, and part or all of snow load can be offset.
In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the embodiments of the invention particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to designate like parts throughout the drawings;
FIG. 1a is a schematic view of a prestress reinforcement wood frame according to the present invention;
FIG. 1b is a schematic illustration of the positions of the prestressing adjuster rod and the lower chord prestressing tie in the prestress-reinforced wood roof truss provided by the invention;
FIG. 1c is a cross-sectional view A-A of FIG. 1 b;
FIG. 2a is a schematic illustration of the location of an end gusset in a prestressed reinforced wood roof truss according to the present invention;
FIG. 2b is a schematic illustration of the location of the lower chord node plates in the pre-stressed reinforced wood roof truss provided by the present invention;
FIG. 2c is a schematic illustration of the location of the upper chord gusset of the prestress reinforcement wood frame provided by the present invention;
FIG. 3 is a schematic illustration of the connection between a brace and a lower chord, lower chord prestress tie in a prestress reinforced wood roof truss provided by the invention, with snow loading;
FIG. 4 is a schematic illustration of the internal force of the prestressed reinforced wood roof truss according to the first embodiment of the present invention, wherein the internal force is prestressed, dead weight, constant load and live load;
FIG. 5 is a schematic diagram showing the deformation of a prestressed reinforced wood roof truss according to an embodiment of the present invention, wherein the deformation is prestressed, dead weight, constant load and live load;
FIG. 6 is a schematic diagram of the internal force of the existing roof truss subjected to dead weight + constant load + live load;
Fig. 7 is a schematic diagram of deformation of the existing roof truss subjected to dead weight, constant load and live load.
Reference numerals:
1-an upper chord; 2-bottom chords; 3-vertical web members; 4-lower chord prestress pull rod; 5-vertical web prestressing tie rod; 6-end gusset plates; 7-a lower chord node plate; 8-upper chord node plates; 9-a prestress adjusting rod; 10-hanging rods; 11-a support cylinder; 12-supporting plates; 13-turning handle; 14-a first threaded rotating rod; 15-a second threaded rotating rod; 16-a first threaded sleeve; 17-a second threaded sleeve; 18-a first height-adjusting rod; 19-a second height-adjusting rod; 20-locking clips.
Detailed Description
The following detailed description of preferred embodiments of the invention is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the invention, are used to explain the principles of the invention and are not intended to limit the scope of the invention.
The invention provides a prestress reinforced wood roof truss, which is shown in figure 1a and comprises an original roof truss and a reinforcing device.
The original roof truss comprises an upper chord member 1, a lower chord member 2 and vertical web members 3, wherein the number of the upper chord members 1 is 2, the number of the lower chord members 2 is 1, the number of the vertical web members 3 is multiple, the two upper chord members 1 and the lower chord members 2 are connected to form a triangle, the vertical web members 3 are located between the upper chord members 1 and the lower chord members 2, the upper ends of the vertical web members 3 are fixedly connected with the upper chord members 1, the lower ends of the vertical web members 3 are fixedly connected with the lower chord members 2, the vertical web members 3 are arranged along the vertical direction, and the vertical web members 3 are arranged in parallel.
The reinforcing device comprises a lower chord prestress pull rod 4 and a vertical web prestress pull rod 5, wherein the lower chord prestress pull rod 4 is arranged along the lower chord member 2, is arranged at the lower part of the lower chord member 2 and is fixedly connected with the lower chord member 2, prestress is applied to the lower chord member 2 through the lower chord prestress pull rod 4, one end of the lower chord prestress pull rod 4 is fixedly connected with the lower chord member 2, the other end of the lower chord prestress pull rod 4 is fixedly connected with the other end of the lower chord member 2, the middle parts of the lower chord prestress pull rod 4 and the lower chord member are not connected, the vertical web prestress pull rod 5 is arranged along the vertical web member 3, coincides with the vertical web member 3 and is fixedly connected with the vertical web member 3, and prestress is applied to the vertical web member 3 through the vertical web prestress pull rod 5.
The prestress of the lower chord prestress pull rod 4 and the vertical web prestress pull rod 5 is regulated, and the lower chord member 2 and the vertical web member 3 bear pressure under the premise of only considering the gravity of the wood roof truss. In actual use, the lower chord 2 and the vertical web members 3 also bear roof loads, such that the lower chord 2 and the vertical web members 3 change from being under compression to not being under compression or to being under less tension.
According to calculation and analysis, under the action of dead weight and roof load (constant load, full span active load and half span active load), the lower chord member 2 and the vertical web member 3 of the original roof truss are always subjected to tensile force, the upper chord member 1 is always subjected to compressive force, and the section strength of the members (namely the upper chord member 1, the lower chord member 2 and the vertical web member 3) of the original roof is weakened again due to the fact that the tensile strength of wood is lower than the compressive strength, and the holes, the cracks, the corrosion and the like in the manufacture and the actual use of the original roof truss are caused, so that the pull members (namely the lower chord member 2 and the vertical web member 3) cannot meet the existing bearing capacity requirement.
Compared with the prior art, the wood roof truss with the prestress reinforcement is characterized in that the lower chord prestress pull rod 4 and the vertical web prestress pull rod 5 are additionally arranged on the basis of the original roof truss, the lower chord prestress pull rod 4 is used for prestress reinforcement of the lower chord member 2, the vertical web member 3 is subjected to prestress reinforcement through the vertical web prestress pull rod 5, and the prestress applied by the lower chord prestress pull rod 4 and the vertical web member 3 is regulated, so that the tension force of the lower chord member 2 and the vertical web member 3 is reduced or even zero, further damage to the tension force of the lower chord member 2 and the vertical web member 3 can be effectively reduced or even avoided, the integral bearing capacity of the wood roof truss is improved on the premise that the original roof truss timber is not replaced or replaced as little as possible, and the potential safety hazard of the original roof truss is eliminated.
For the setting position of the lower chord prestressing drawn rod 4, the lower chord prestressing drawn rod 4 is located below the lower chord 2, for example.
Correspondingly, for the setting position of the vertical web prestress pull rod 5, the vertical web rod 3 is divided into a central vertical web rod 3 positioned at the center of the wood roof truss and side vertical web rods 3 positioned at two sides of the central vertical web rod 3, the central vertical web rod 3 corresponds to 4 vertical web prestress pull rods 5, the front end face of the central vertical web rod 3 is provided with 2 vertical web prestress pull rods 5, the rear end face of the central vertical web rod 3 is provided with 2 vertical web prestress pull rods 5, each side vertical web rod 3 corresponds to 2 vertical web prestress pull rods 5, one vertical web prestress pull rod 5 is positioned at one side of the side vertical web rod 3, which faces away from the central vertical web rod 3, and the other vertical web prestress pull rod 5 is positioned at one side of the side vertical web rod 3, which faces the central vertical web rod 3, so that a symmetrical structure can be formed, and the overall reinforcing stress uniformity of the wood roof truss is ensured.
In order to further counteract the deformation of the roof truss structure, a brace (e.g. a round steel tube) is provided between the lower chord prestressed tension rod 4 and the lower chord 2, and the lower chord prestressed tension rod 4 is in intimate contact with the lower chord 2 via the brace, and illustratively, the location of the brace corresponds to the intersection point of the vertical web member 3 and the lower chord 2, and the prestress of the lower chord prestressed tension rod 4 is adjusted so that the lower chord prestressed tension rod 4 supports part of the lower chord 2 via the brace, thereby forming an inverted arch, taking only the weight of the roof truss into consideration. Thus, in actual use, the wood roof truss also bears roof constant load, and deformation of the roof truss structure is further counteracted by the inverted arch structure.
It is noted that the stability of the connection between the upper chord 1, the lower chord 2 and the vertical web 3 also affects the overall load bearing capacity of the original roof, and therefore the pre-stressed wood roof truss described above further comprises end node plates 6, lower chord node plates 7 and upper chord node plates 8, see fig. 2a, 2b and 2c.
The end node is a connection node of the upper chord 1 and the lower chord 2, the end node plate 6 is located at a connection node of the upper chord 1 and the lower chord 2, the end node plate 6 is used for reinforcing the connection node of the upper chord 1 and the lower chord 2, the end of the lower chord prestress pull rod 4, the upper chord 1 and the lower chord 2 are fixedly connected through the end node plate 6, in the service process of the wood roof truss, two ends of the lower chord prestress pull rod 4 are connected with the end node plate 6, and the tension force of the lower chord prestress pull rod 4 is transferred to the end node plate 6.
The lower chord node is a connecting node of the vertical web member 3 and the lower chord member 2, and the lower chord node plate 7 is positioned at the connecting node of the vertical web member 3 and the lower chord member 2 and used for reinforcing the connecting node of the vertical web member 3 and the lower chord member 2, and the lower end of the vertical web prestress pull rod 5, the lower chord member 2 and the vertical web member 3 are fixedly connected through the lower chord node plate 7.
The upper chord node is a connecting node of the vertical web member 3 and the upper chord member 1, and the upper chord node plate 8 is positioned at the connecting node of the vertical web member 3 and the upper chord member 1 and used for reinforcing the connecting node of the vertical web member 3 and the upper chord member 1, and the upper end of the vertical web prestress pull rod 5, the upper chord member 1 and the vertical web member 3 are fixedly connected through the upper chord node plate 8.
The upper end of the web prestressing rod 5 is connected to the upper chord node plate 8 by a tension nut.
On the one hand, the upper chord member 1, the lower chord member 2, the vertical web member 3, the lower chord prestress pull rod 4 and the vertical web prestress pull rod 5 can be connected to form a whole through the arrangement of the end node plate 6, the lower chord node plate 7 and the upper chord node plate 8, so that the stability of the whole structure of the wood roof truss is ensured; on the other hand, the connection of the vertical web member 3, the upper chord member 1 and the lower chord member 2 is mostly joggled or creeping nail connection, deformation and rod piece separation are easy to occur under the action of tensile force, and great potential safety hazards exist, and through the arrangement of the end node plate 6, the lower chord node plate 7 and the upper chord node plate 8, each node can be effectively reinforced, and the bearing capacity of the prestress reinforced wood roof truss is further improved.
Likewise, in order to improve the connection stability of the two upper chords 1, the prestress-reinforced wood roof truss further comprises a U-shaped plate, the two upper chords 1 are fixedly connected through the U-shaped plate, the connection nodes of the two upper chords 1 are reinforced through the U-shaped plate, the connection node strength of the two upper chords 1 is ensured, and the axial forces of the upper chords 1 and the lower chords 2 are digested.
It is noted that in winter snow is additionally borne by the wood roof truss, but in summer snow load is not required to be considered, in order to be able to adaptively adjust the prestress applied by the lower chord prestress tension rod 4, the prestress-reinforced wood roof truss further comprises prestress adjusting rods 9, see fig. 1b to 1c, the linear expansion coefficient of the prestress adjusting rods 9 is larger than that of the lower chord prestress tension rod 4, the prestress adjusting rods 9 are arranged along the direction of the lower chord prestress tension rod 4, and two ends of the prestress adjusting rods 9 are fixedly connected with the lower chord prestress tension rod 4 through locking clips 20. Thus, by setting the prestressing force adjusting rod 9, and the linear expansion coefficient of the prestressing force adjusting rod 9 is larger than that of the lower chord prestressing force pull rod 4, the characteristic that the prestressing force adjusting rod 9 expands with heat and contracts with cold is utilized, when in summer, the prestressing force adjusting rod 9 does not apply prestressing force to the lower chord prestressing force pull rod 4, when in winter, the prestressing force adjusting rod 9 contracts itself, and prestressing force is applied to the lower chord prestressing force pull rod 4, so that the prestressing force applied to the lower chord member 2 is increased, and part or all of snow load can be offset.
Illustratively, the lower chord prestress pull rod 4 is made of steel, the thermal expansion coefficient of the steel bar is 11.7X10 -6 m/m DEG C, the prestress adjusting rod 9 is made of aluminum alloy, and the linear expansion coefficient of the aluminum alloy is 23.8X10 -6 m/m DEG C.
The number of the prestress adjusting rods 9 is two; one of the prestress adjusting rods 9 is close to one end of the lower chord prestress tension rod 4, and the other prestress adjusting rod 9 is close to the other end of the lower chord prestress tension rod 4
In order to fully utilize the thermal expansion and contraction characteristics of the prestress adjusting rod 9 to further improve the prestress applied to the lower chord member 2, the length of the prestress adjusting rod 9 should not be too short, and it is recommended to be not less than 1m.
Or for the balancing of snow load, the following manner may be adopted:
For the structure of the stay bar, see fig. 3, specifically, the stay bar comprises a hanging rod 10, a supporting cylinder 11, a supporting plate 12, a rotating handle 13, a first threaded rotating rod 14, a second threaded rotating rod 15, a first threaded sleeve 16, a second threaded sleeve 17, a first heightening rod 18 and a second heightening rod 19, wherein the upper end of the supporting cylinder 11 is opened, the hanging rod 10 is arranged on the outer side of the supporting cylinder 11, and the supporting plate 12 is arranged above the supporting cylinder 11; the supporting cylinder 11 is fixedly connected with the lower chord prestress pull rod 4; one end of the rotating handle 13 is rotationally connected with the upper end of the hanging rod 10, the lower end of the hanging rod 10 is clamped with the lower surface of the lower chord prestress pull rod 4 when snow load exists, the lower surface of the hanging rod is in a free state when no snow load exists, one end of the first threaded rotating rod 14 penetrates through one side of the supporting cylinder 11 and is fixedly connected with the other end of the rotating handle 13, the other end of the first threaded rotating rod 14 is fixedly connected with one end of the second threaded rotating rod 15, and the other end of the second threaded rotating rod 15 is rotationally connected with the other side of the supporting cylinder 11; the first threaded sleeve 16 is sleeved on the outer wall of the first threaded rotating rod 14 and is in threaded connection with the first threaded rotating rod 14, the second threaded sleeve 17 is sleeved on the outer wall of the second threaded rotating rod 15 and is in threaded connection with the second threaded rotating rod 15, and the threaded direction of the first threaded rotating rod 14 is opposite to that of the second threaded rotating rod 15; one end of a first height-adjusting rod 18 is rotationally connected with the first threaded sleeve 16, the other end of the first height-adjusting rod 18 is rotationally connected with the supporting plate 12, the other end of a second height-adjusting rod 19 is rotationally connected with the second threaded sleeve 17, and the other end of the second height-adjusting rod 19 is rotationally connected with the supporting plate 12; the cross section of the structure formed by part of the first screw thread rotating rod 14, part of the second screw thread rotating rod 15, the first heightening rod 18, the second heightening rod 19 and part of the supporting plate 12 is trapezoid.
When snow load is generated by snowing, an operator hangs the lower end of the hanging rod 10 on the lower surface of the lower chord 2 in a downward movement manner, and the hanging rod 10 drives the first threaded rotating rod 14 and the second threaded rotating rod 15 to rotate through the rotating handle 13; because the screw thread directions of the first screw thread rotating rod 14 and the second screw thread rotating rod 15 are opposite, the rotation of the first screw thread rotating rod 14 and the second screw thread rotating rod 15 enables the first screw thread sleeve 16 and the second screw thread sleeve 17 to be close to each other in the horizontal direction, the angle between the first heightening rod 18 and the second heightening rod 19 and the horizontal direction is driven to be increased, the vertical height of the first heightening rod 18 and the second heightening rod 19 is increased, and then the supporting plate 12 is driven to move upwards, and the downward movement of the lower chord member 2 caused by snow load is resisted.
Illustratively, the span of the original roof truss is 8-12 m, the span middle height is 2-4 m, the constant load of the roof is 8-13 KN/m, the live load of the roof is 1.5-3 KN/m, the prestress applied by the lower chord prestress pull rod 4 is 45-55 KN, the prestress applied by the vertical web prestress pull rod 5 is 7-15 KN, and the pressure generated by the lower chord member 2 is 45-50 KN under the premise of only considering the prestress and the wood roof truss gravity, and the prestress of the lower chord prestress pull rod 4 is balanced by the lower chord member 2 of the wood roof truss; the pressure generated by the central vertical web member 3 is 15-18 KN, the pressure generated by the side vertical web members 3 is 9-11 KN, and the prestress of the vertical web prestress pull rod 5 is balanced by the vertical web members 3 of the wood roof truss.
Example 1
The present embodiment analyzes the improvement of the internal force and deformation of the prestress reinforced wood frame by a specific engineering example.
Specifically, the span of the original roof truss is 10m, the span height is 3m, the constant load of the roof is 10KN/m, the live load of the roof is 2KN/m, the prestress applied by the lower chord prestress pull rod is 50KN, and the prestress applied by the vertical web prestress pull rod is 10KN.
Under the premise of considering only the prestress and the gravity of the wood roof truss, the pressure generated by the lower chord member is 48.3KN, the prestress of the lower chord prestress pull rod is balanced by the lower chord member of the wood roof truss, that is, the pressure generated by the prestress applied to the lower chord prestress pull rod on the lower chord member of the wood roof truss is basically equal, and the prestress of the lower chord prestress pull rod is borne by the lower chord member only, so that other members of the wood roof truss are not basically influenced, and particularly, no additional internal force is generated on the upper chord member; the pressure generated by the central vertical web member is 16.7KN, the pressure generated by the side vertical web members is 9-11 KN, namely, the prestress of the vertical web prestress pull rod is balanced by the vertical web members of the wood roof truss, that is, the pressure generated by the prestress applied to the vertical web prestress pull rod on the vertical web members of the wood roof truss is basically equal, the prestress of the vertical web prestress pull rod is born only by the vertical web members, and the prestress of other members of the wood roof truss is basically not influenced, and particularly, the additional internal force is not generated on the upper chord members. At the same time, the bottom chord creates an inverted arch of 1.8mm upwards.
Under the same load, the internal force and deformation of the wood roof truss reinforced by the prestress are shown in fig. 4 to 5, the internal force and deformation of the original roof truss not reinforced by the prestress are shown in fig. 6 to 7, and the comparison of the calculation results of the two schemes is shown in table 1.
Table 1 comparison of internal forces and deformations of reinforced and unreinforced wood roof truss
| Prestress reinforcement | Unreinforced (not reinforced) | Data proportion | |
| Lower chord tension (KN) | 30.4 | 103 | 0.30 |
| Upper chord pressure (KN) | 126.3 | 126.4 | 1.00 |
| Center vertical web member tension (KN) | 25.7 | 56.0 | 0.46 |
| Side vertical web member tension (KN) | 6.7 | 25.2 | 0.26 |
| Maximum vertical displacement (mm) | 6.4 | 9.9 | 0.65 |
By comparison, it can be seen that:
On the one hand, the prestress reinforced wood roof truss is adopted, the lower chord member tension is 30% of the original roof truss, the central vertical web member tension is 46% of the original roof truss, the side vertical web member tension is 26% of the original roof truss, the prestress is added to enable the stress of the lower chord member and the vertical web member of the original roof truss to be greatly reduced, and the original roof truss can meet the stress requirement without replacement. On the other hand, the prestress reinforcement improves the vertical displacement of the wood roof truss, and the calculation result is only 65% of that of the original roof truss; in yet another aspect, the pre-stressing does not increase the load on the upper chord.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. The prestress reinforced wood roof truss is characterized by comprising an original roof truss and a reinforcing device;
The original roof truss comprises two upper chords, one lower chord and one vertical web member, wherein the number of the upper chords is two, the number of the lower chords is one, the two upper chords and the one lower chord are connected to form a triangle, the upper end of the vertical web member is fixedly connected with the upper chord, and the lower end of the vertical web member is fixedly connected with the lower chord;
the reinforcing device comprises a lower chord prestress pull rod, a vertical web prestress pull rod and a prestress adjusting rod;
the lower chord prestress pull rod is arranged along the lower chord member and is arranged at the lower part of the lower chord member, one end of the lower chord prestress pull rod is fixedly connected with the lower chord member, and the other end of the lower chord prestress pull rod is fixedly connected with the other end of the lower chord member;
The vertical web prestress pull rod is arranged along the vertical web member and is overlapped with the vertical web member, the upper end of the vertical web prestress pull rod is fixedly connected with the upper end of the vertical web member, and the lower end of the vertical web prestress pull rod is fixedly connected with the lower end of the vertical web member;
The linear expansion coefficient of the prestress adjusting rod is larger than that of the lower chord prestress pull rod, and the prestress adjusting rod is arranged along the direction of the lower chord prestress pull rod and fixedly connected with the lower chord prestress pull rod;
the span of former roof truss is 8~12m, and span height is 2~4m, and roofing constant load is 8~13KN/m, and roofing live load is 1.5~3KN/m, the prestressing force that lower chord prestressing force pull rod applyed is 45~55KN, the prestressing force that erect abdomen prestressing force pull rod applyed is 7~15KN, the prestressing force of lower chord prestressing force pull rod is all balanced by the lower chord member of former roof truss, the prestressing force of erect abdomen prestressing force pull rod is all balanced by the erect web member of former roof truss.
2. The pre-stressed reinforced wood roof truss of claim 1, wherein a brace is disposed between the lower chord pre-stressing tension rod and the lower chord, the lower chord pre-stressing tension rod being in intimate contact with the lower chord via the brace.
3. The pre-stressed reinforced wood roof truss of claim 2, wherein the brace comprises a hanger bar, a support tube, a support plate, a swivel handle, a first threaded swivel bar, a second threaded swivel bar, a first threaded sleeve, a second threaded sleeve, a first elevation bar, and a second elevation bar;
the upper end of the supporting cylinder is provided with an opening, the hanging rod is arranged on the outer side of the supporting cylinder, and the supporting plate is arranged above the supporting cylinder;
The support cylinder is fixedly connected with the lower chord prestress pull rod;
One end of the rotating handle is rotationally connected with the upper end of the hanging rod, the lower end of the hanging rod is clamped with the lower surface of the lower chord prestress pull rod when snow load exists, one end of the first threaded rotating rod penetrates through one side of the supporting cylinder and is fixedly connected with the other end of the rotating handle, the other end of the first threaded rotating rod is fixedly connected with one end of the second threaded rotating rod, and the other end of the second threaded rotating rod is rotationally connected with the other side of the supporting cylinder;
The first threaded sleeve is sleeved on the outer wall of the first threaded rotating rod and is in threaded connection with the first threaded rotating rod, the second threaded sleeve is sleeved on the outer wall of the second threaded rotating rod and is in threaded connection with the second threaded rotating rod, and the threaded direction of the first threaded rotating rod is opposite to that of the second threaded rotating rod;
one end of the first heightening rod is rotationally connected with the first threaded sleeve, the other end of the first heightening rod is rotationally connected with the supporting plate, one end of the second heightening rod is rotationally connected with the second threaded sleeve, and the other end of the second heightening rod is rotationally connected with the supporting plate;
When snow load is generated by snowing, the lower end of the hanging rod moves downwards to hang on the lower surface of the lower chord prestress pull rod, the hanging rod drives the first threaded rotating rod and the second threaded rotating rod to rotate through the rotating handle, the first threaded sleeve and the second threaded sleeve are close to each other in the horizontal direction, the angle between the first heightening rod and the second heightening rod and the horizontal direction is driven to be increased, and the vertical heights of the first heightening rod and the second heightening rod are increased.
4. A pre-stressed reinforced wood roof truss according to claim 3, wherein the lower chord pre-stressing ties brace a portion of the lower chord by braces to form an inverted arch.
5. The pre-stressed wood roof truss of claim 1, wherein the pre-stressed adjustment bar is fixedly attached at both ends to the lower chord pre-stressed tie bar by means of locking clips.
6. The pre-stressed reinforced wood roof truss of claim 1, wherein the number of pre-stress adjustment bars is two;
one of the prestress adjusting rods is close to one end of the lower chord prestress pull rod, and the other prestress adjusting rod is close to the other end of the lower chord prestress pull rod.
7. The pre-stressed reinforced wood roof truss of claim 1, wherein the length of the pre-stress adjustment bar is greater than or equal to 1m.
8. The pre-stressed reinforced wood roof truss of claim 1, wherein the original roof truss further comprises a U-shaped plate, and wherein the two upper chords are fixedly connected by the U-shaped plate.
9. The pre-stressed wood roof truss of claim 1, wherein the lower chord pre-stressed tie is steel.
10. The pre-stressed wood roof truss of claim 1, wherein the pre-stress adjustment bar is made of aluminum alloy.
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| KR101065633B1 (en) * | 2010-10-05 | 2011-09-20 | 대명건설(주) | Prestressed steel tubular truss beam by external prestressing method |
| CN105421813B (en) * | 2015-12-07 | 2017-10-13 | 中国建筑第八工程局有限公司 | The external prestress strengthening method of concrete truss |
| CN106930467B (en) * | 2017-05-08 | 2020-05-08 | 南京工业大学 | Combined roof truss with FRP cable at lower chord |
| CN110821204A (en) * | 2017-10-16 | 2020-02-21 | 叶长青 | Reinforcement construction method of concrete roof beam |
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| CN217175906U (en) * | 2022-03-25 | 2022-08-12 | 郑州大学 | Concrete floor reinforcing structure and combined truss |
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| CN217400442U (en) * | 2022-06-15 | 2022-09-09 | 中建一局华江建设有限公司 | Steel construction reinforced (rfd) large-span wood roof truss structure |
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