A broken line shaped prefabricated concrete roof truss template fastening fixture and a construction method based thereon

Abstract

This invention relates to the field of building construction technology, and in particular to a formwork fastening clamp for a zigzag precast concrete roof truss and a construction method based thereon. The formwork fastening clamp includes a first insert, a second insert, a bottom crossbar, and a locking device. The bottom crossbar is connected to the first and second inserts via a socket joint and is locked in place by the locking device. This invention solves the problems existing in the prior art and provides an integrated solution for formwork fastening, sleeper support, hoisting gap reservation, and prevention of concrete adhesion. After the precast beam is demolded, the bottom crossbar can be directly left below the beam to act as a sleeper, and the upper beam can still be directly precast on top of the lower beam. During hoisting, there is a rope gap between the two beams, which effectively avoids concrete adhesion between the upper and lower beams, improving the forming quality and construction efficiency of the zigzag precast concrete roof truss.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a zigzag-shaped precast concrete roof truss formwork fastening clamp and a construction method based thereon. Background Technology

[0002] Zygmalion-shaped precast concrete roof trusses are typically used in large-span bungalows with spans exceeding 25 meters. Their upper chord is zigzag-shaped, closely resembling the roof load line, resulting in uniform internal forces within the members. Compared to traditional steel roof trusses, this significantly reduces the workload of high-altitude hoisting and on-site assembly during steel structure construction. It solves a series of pain points affecting construction schedule and quality, such as cumbersome construction processes, low safety, high material costs, difficulty in controlling welding quality, and numerous high-altitude operations. Zygmalion-shaped precast concrete roof trusses exhibit strong integrity, good spatial stability, and superior seismic and lateral displacement resistance compared to traditional steel roof trusses, making them suitable for factories with seismic intensity of 7-8 degrees. Furthermore, zigmalion-shaped precast concrete roof trusses use less concrete and steel reinforcement, resulting in lighter weight and indirectly reducing the load on lower columns and foundations, lowering foundation costs, and saving more materials than steel roof trusses for the same span.

[0003] The zigzag precast concrete roof truss utilizes a prestressed concrete structure, offering fire resistance, corrosion resistance, and aging resistance. It requires minimal maintenance and boasts a service life far exceeding that of steel roof trusses. Furthermore, the zigzag precast concrete roof truss primarily employs a horizontal, layered prefabrication method, enabling mass production and centralized curing. This results in high site utilization, high prefabrication efficiency, a high first-pass yield rate for components, and low construction difficulty. It can be constructed using either a prefabrication plant with on-site hoisting or on-site prefabrication in open areas, minimizing disruption to existing construction work, reducing the number of construction steps, and improving overall construction efficiency.

[0004] When constructing a zigzag precast concrete roof truss, high precision is required in the positioning of the formwork, as well as its rigidity and uniform stress distribution. Traditional formwork fixing methods often employ single-point reinforcement using steel pipe couplers and tie bolts, which suffers from problems such as loose fit at the zigzag section, easy formwork bulging and grout leakage, uneven reinforcement stress, low assembly and disassembly efficiency, and poor versatility. Furthermore, traditional precasting methods commonly involve directly precasting the upper beam on top of the lower beam, only applying a release agent to the lower beam's top surface. Due to the high concrete grade and long curing time of the precast beams, concrete adhesion is highly likely; and during hoisting, the lack of gap between the two precast beams makes rope threading difficult.

[0005] Therefore, there is an urgent need for a formwork fastening clamp that is quick-adjustable and reliably locked and compatible with the zigzag precast concrete roof truss, as well as a construction method that can prevent concrete adhesion, has a high turnover rate, is easy to install and dismantle, and is easy to hoist. Summary of the Invention

[0006] This invention solves the problems existing in the prior art and provides a formwork fastening clamp for a zigzag precast concrete roof truss and a construction method based thereon. It adopts an integrated solution for formwork fastening, sleeper support, hoisting gap reservation, and prevention of concrete adhesion. After the precast beam is demolded, the bottom crossbar can be directly left under the beam to serve as a sleeper, and the upper beam can still be directly precast on the top surface of the lower beam. During hoisting, there is a rope gap between the two beams, which effectively avoids concrete adhesion between the upper and lower beams, thus improving the forming quality and construction efficiency of the zigzag precast concrete roof truss.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A zigzag-shaped precast concrete roof truss formwork fastening clamp includes insert one, insert two, a bottom horizontal bar, and a locking device. The top surface of the bottom horizontal bar directly contacts the concrete. Inserts one and two are located around the perimeter of the formwork, and the bottom horizontal bar is connected to inserts one and two via a socket joint. After being locked in place by the locking device, they form the formwork fastening clamp. Insert one is an L-shaped structure composed of a horizontal bar and a vertical bar, and insert two is an L-shaped structure composed of a horizontal bar and a vertical bar. Horizontal bars one and two are inserted together. The horizontal bar one... Multiple positioning holes are provided, and a fixing hole is provided on the second horizontal bar; the two ends of the bottom horizontal bar are respectively provided with pole insertion hole one and pole insertion hole two, and pole one and pole two are inserted into the corresponding pole insertion hole one and pole insertion hole two respectively; the inner distance between pole insertion hole one and pole insertion hole two is equal to the cross-sectional width of the roof truss beam at the corresponding position + template thickness + back rib thickness; the lock includes a plate, the positioning holes and fixing holes are the same size, the thickness of the plate is less than the width of the positioning holes and fixing holes in the corresponding direction, and a gasket is provided at the gap.

[0008] Both plug-in 1 and plug-in 2 are made of rectangular tubing, while the bottom crossbar is made of square tubing.

[0009] The lock consists of a plate, a top plate, and a handle. The top plate is vertically connected to the plate, and the top surface of the top plate is equipped with a handle.

[0010] A construction method based on the aforementioned polygonal precast concrete roof truss formwork fastening clamp includes the following steps: (1) Before the prefabrication of the zigzag precast concrete roof truss, the installation position of the template fastening clamps shall be determined according to the template design drawing, and the space for the bottom horizontal bar shall be reserved. Before the template is installed, the bottom horizontal bar shall be placed in the set position, and then the template shall be assembled. After the template is installed and the dimensions of each part are verified to be qualified, the template back ribs and template surface that are in direct contact with the template fastening clamps shall be cleaned. (2) At each template fastening clamp installation location, adjust the insertion length of plug-in one and plug-in two according to the cross-sectional width of the corresponding part of the roof truss beam, the template thickness and the back rib thickness, thus completing the length pre-adjustment; (3) Insert the first upright of plug-in 1 and the second upright of plug-in 2 into the corresponding upright insertion hole 1 and upright insertion hole 2 of the bottom crossbar respectively, so that each member of plug-in 1 and plug-in 2 fits tightly against the template or template back rib of the corresponding part. Then adjust the overall angle of the template fastening clamp to make it perpendicular to the beam of the corresponding part. Finally, insert the insert plate in the lock into the corresponding positioning insertion hole and fixing insertion hole. The gap between the insert plate and the insertion hole is tightened and fixed by adding a shim. (4) After all the template fastening clamps are installed, inspect them. Use sponge strips or sealant to seal the template joints, bolt holes and the junction of the template and the fixed mold base to prevent grout leakage. (5) After the concrete pouring is completed and the demolding strength is reached, remove the lock and remove plug 1 and plug 2 as a whole from the bottom crossbar. The bottom crossbar is left below the precast beam. (6) When the zigzag precast concrete roof truss is precast in layers, the bottom crossbar forms a uniform gap between the upper and lower beams, which not only avoids the concrete from sticking together between the upper and lower beams, but also allows the hoisting rope to pass through the gap between the two beams for hoisting.

[0011] Compared with the prior art, the beneficial effects of the present invention are: (1) The template fastening clamp adopts a socket structure, which is convenient and quick to install and disassemble: Plug 1, Plug 2 and bottom crossbar are all socket connections, which do not require welding. Multiple sockets are prefabricated, which is highly adaptable, and the installation and disassembly are convenient and quick, greatly improving the construction efficiency.

[0012] (2) One material for multiple uses: After demolding, the bottom crossbar is left directly under the beam to serve as sleeper, and there is no need to lay support pads between beams of each layer, which reduces the construction process.

[0013] (3) Reserved hoisting gap: After the bottom crossbar is placed, a gap is formed between the beams of each layer. The hoisting rope can easily pass through during hoisting. Compared with the method of manually prying the gap when applying the release agent, it is easier to hoist.

[0014] (4) The problem of concrete adhesion has been completely solved: the bottom crossbars isolate the upper and lower beams, completely preventing the concrete from sticking together and ensuring the integrity and appearance quality of the beams.

[0015] (5) Strong versatility: The template fastening clamp has the characteristics of "expansion and contraction adjustment and socket positioning", which can be adapted to the zigzag precast concrete roof trusses of different heights, spans and thicknesses.

[0016] (6) Reliable reinforcement: After the template fastening clamps are used, the template is subjected to uniform force and the fold lines are tightly fitted, which can effectively avoid problems such as bulging, leakage, and deformation.

[0017] (7) Economical and durable: The template fastening clamps can be made of square tubes and steel plates. The structure is simple, the overall strength is high, and it can be reused, which helps to reduce construction costs. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of the plug-in described in this invention.

[0019] Figure 2 This is a three-dimensional structural diagram of the second plug-in described in this invention.

[0020] Figure 3 This is a three-dimensional structural diagram of the bottom crossbar described in this invention.

[0021] Figure 4 This is a three-dimensional structural diagram of the positioning insert described in this invention.

[0022] Figure 5 This is a schematic diagram of the combination of plug-in one and plug-in two described in this invention.

[0023] Figure 6 This is a schematic diagram of the combination of the template fastening clamp described in this invention.

[0024] In the diagram: 1-Plug 1; 11-Horizontal bar 1; 12-Upright bar 1; 13-Positioning hole; 2-Plug 2; 21-Horizontal bar 2; 22-Upright bar 2; 23-Fixing hole; 3-Bottom horizontal bar; 31-Upright bar insertion hole 1; 32-Upright bar insertion hole 2; 4-Lock; 41-Insertion plate; 42-Top plate; 43-Handle. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 6 As shown, the present invention provides a zigzag-shaped precast concrete roof truss formwork fastening clamp, comprising insert 1, insert 2, bottom crossbar 3, and locking device 4; wherein the top surface of the bottom crossbar 3 directly contacts the concrete, insert 1 and insert 2 are located around the formwork, and the bottom crossbar 3 is connected to insert 1 and insert 2 by a socket joint, and is locked and fixed by the locking device 4 to form the formwork fastening clamp; as shown Figure 1 As shown, the plug-in 1 is an L-shaped structure composed of a crossbar 11 and a vertical bar 12, as follows: Figure 2 As shown, plug-in 2 is an L-shaped structure composed of crossbar 21 and upright 22, with crossbar 11 and crossbar 21 plugged in; multiple positioning holes 13 are provided on crossbar 11, and fixing holes 23 are provided on crossbar 21; as shown Figure 3As shown, the bottom crossbar 3 has pole insertion hole 1 31 and pole insertion hole 2 32 at both ends, and pole 1 12 and pole 2 22 are inserted into the corresponding pole insertion hole 1 31 and pole insertion hole 2 32, respectively; the inner distance between pole insertion hole 1 31 and pole insertion hole 2 32 is equal to the cross-sectional width of the roof truss beam at the corresponding position + template thickness + back rib thickness; the lock 4 includes a plate 41, and the positioning insertion hole 13 and fixing insertion hole 23 are the same size. The thickness of the plate 41 is less than the width of the positioning insertion hole 13 and fixing insertion hole 23 in the corresponding direction. A shim is provided at the gap (the gap between the plate 41 and the insertion hole is used for fine adjustment, and after adjustment, a shim is added at the gap to lock and fix it).

[0026] Both plug-in 1 and plug-in 2 are made of rectangular tubing, while the bottom crossbar 3 is made of square tubing.

[0027] like Figure 4 As shown, the lock 4 consists of a plate 41, a top plate 42 and a handle 43. The top plate 42 is vertically connected to the plate 41, and the top surface of the top plate 42 is provided with a handle 43.

[0028] The construction method based on a polygonal precast concrete roof truss formwork fastening clamp of the present invention includes the following steps: (1) Before the prefabrication of the zigzag precast concrete roof truss, the installation position of the template fastening clamps shall be determined according to the template design drawing, and the placement space of the bottom horizontal bar 3 shall be reserved. Before the template is installed, the bottom horizontal bar 3 shall be placed in the set position, and then the template shall be assembled. After the template is installed and the dimensions of each part are verified to be qualified, the template back ribs and template surface that are in direct contact with the template fastening clamps shall be cleaned. (2) At each template fastening clamp installation point, adjust the insertion length of plug-in 1 and plug-in 2 according to the cross-sectional width of the corresponding part of the roof truss beam, the template thickness and the back rib thickness, thus completing the length pre-adjustment (e.g. Figure 5 (as shown) (3) such as Figure 6 As shown, insert the upright 12 of plug-in 1 and the upright 22 of plug-in 2 into the corresponding upright insertion holes 31 and 32 of the bottom crossbar 3, respectively, so that each member of plug-in 1 and plug-in 2 fits tightly against the template or template back rib of the corresponding part (i.e., the template fastening clamp fits tightly against the template). Then adjust the overall angle of the template fastening clamp to make it perpendicular to the beam of the corresponding part. Finally, insert the insert plate 41 in the lock 4 into the corresponding positioning insertion hole 13 and fixing insertion hole 23. The gap between the insert plate 41 and the insertion hole (including the positioning insertion hole 13 and the fixing insertion hole 23) is tightened by adding a shim. (4) After all the template fastening clamps are installed, inspect them. Use sponge strips or sealant to seal the template joints, bolt holes and the junction of the template and the fixed mold base to prevent grout leakage. (5) After the concrete pouring is completed and the demolding strength is reached, take out the lock 4, remove the plug 1 and plug 2 as a whole from the bottom crossbar 3, and leave the bottom crossbar 3 under the precast beam. (6) When the zigzag precast concrete roof truss is precast in layers, the bottom crossbar 3 forms a uniform gap between the upper and lower beams, which not only avoids the concrete sticking between the upper and lower beams, but also allows the hoisting rope to pass through the gap between the two beams for hoisting.

[0029] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0030] Example: In this embodiment, the fastening fixture for the zigzag precast concrete roof truss formwork includes insert one, insert two, bottom crossbar, and lock.

[0031] The first horizontal bar of the first plug is made of a rectangular steel tube with a cross section length of 50mm × 30mm × 2.5mm (wall thickness), and the first vertical bar is made of a rectangular steel tube with a cross section length of 40mm × 30mm × 3mm (wall thickness). Four positioning holes with a cross section length of 40mm × 5mm are opened on the first horizontal bar.

[0032] The second horizontal bar of the plug is made of a rectangular steel tube with a wall thickness of 55mm×35mm×2.5mm, and the second vertical bar is made of a rectangular steel tube with a wall thickness of 40mm×30mm×3mm. A 40mm×5mm fixing hole is opened on the second horizontal bar. When connecting, the second horizontal bar is inserted into the outside of the first horizontal bar.

[0033] The bottom crossbar is made of a rectangular steel tube with a cross-sectional length of 50mm × 50mm × 5mm (wall thickness). Two upright insertion holes, each 40mm × 30mm, are opened at each end. The inner distance between upright insertion holes one and two is equal to the cross-sectional width of the roof truss beam at the corresponding position, plus the thickness of the formwork and the thickness of the back brace.

[0034] The lock consists of a plate, a top plate, and a handle. The plate and top plate are made of steel plates measuring 40mm (width) × 60mm (length) × 5mm (thickness), and the handle is made of ø12 steel bars.

[0035] In this embodiment, after the template and template fastening clamps are installed, concrete is poured. After the template reaches the demolding strength, the lock is removed, and plug-in one and plug-in two are removed from the bottom crossbar as a whole. The bottom crossbar is left below the beam as a sleeper. Plug-in one, plug-in two and the lock are reused.

[0036] In this embodiment, the zigzag precast concrete roof truss is precast in layers, with a total of 4 layers. The bottom crossbars form a uniform gap between the upper and lower beams, and there is no concrete adhesion between the upper and lower beams. During hoisting, the hoisting rope passes between the two beams and lifts each beam in sequence.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A type of fastening clamp for precast concrete roof truss formwork, characterized in that, The system includes insert one, insert two, a bottom crossbar, and a locking device. The top surface of the bottom crossbar is in direct contact with the concrete. Inserts one and two are located around the perimeter of the formwork. The bottom crossbar is connected to inserts one and two through a socket joint, and the formwork fastening fixture is formed by locking the bottom crossbar. Insert one is an L-shaped structure composed of a crossbar and a vertical bar, and insert two is an L-shaped structure composed of a crossbar and a vertical bar. Crossbar one and crossbar two are inserted into each other. Multiple positioning holes are provided on crossbar one, and fixing holes are provided on crossbar two. The bottom crossbar has a vertical bar insertion hole one and a vertical bar insertion hole two at its two ends, and vertical bars one and two are inserted into the corresponding vertical bar insertion holes one and two, respectively. The inner distance between vertical bar insertion holes one and two is equal to the cross-sectional width of the roof truss beam at the corresponding position + the formwork thickness + the back rib thickness. The locking device includes a plate. The positioning holes and fixing holes are the same size. The thickness of the plate is less than the width of the positioning holes and fixing holes in the corresponding direction. A gasket is provided at the gap.

2. The fastening clamp for a polygonal precast concrete roof truss formwork according to claim 1, characterized in that, Both plug-in 1 and plug-in 2 are made of rectangular tubing, while the bottom crossbar is made of square tubing.

3. The fastening clamp for a polygonal precast concrete roof truss formwork according to claim 1, characterized in that, The lock consists of a plate, a top plate, and a handle. The top plate is vertically connected to the plate, and the top surface of the top plate is equipped with a handle.

4. A construction method based on the fastening clamps for the polygonal precast concrete roof truss formwork as described in claim 1, 2, or 3, characterized in that, Includes the following steps: (1) Before the prefabrication of the zigzag precast concrete roof truss, the installation position of the template fastening clamps shall be determined according to the template design drawing, and the space for the bottom horizontal bar shall be reserved; before the template is installed, the bottom horizontal bar shall be placed in the set position, and then the template shall be assembled. After the template installation is completed and all dimensions are verified to be within acceptable limits, clean the template back ribs and template surface that are in direct contact with the template fastening clamps. (2) At each template fastening clamp installation location, adjust the insertion length of plug-in one and plug-in two according to the cross-sectional width of the corresponding part of the roof truss beam, the template thickness and the back rib thickness, thus completing the length pre-adjustment; (3) Insert the first upright of plug-in 1 and the second upright of plug-in 2 into the corresponding upright insertion hole 1 and upright insertion hole 2 of the bottom crossbar respectively, so that each member of plug-in 1 and plug-in 2 fits tightly against the template or template back rib of the corresponding part. Then adjust the overall angle of the template fastening clamp to make it perpendicular to the beam of the corresponding part. Finally, insert the insert plate in the lock into the corresponding positioning insertion hole and fixing insertion hole. The gap between the insert plate and the insertion hole is tightened and fixed by adding a shim. (4) After all the template fastening clamps are installed, inspect them. Use sponge strips or sealant to seal the template joints, bolt holes and the junction of the template and the fixed mold base to prevent grout leakage. (5) After the concrete pouring is completed and the demolding strength is reached, remove the lock and remove plug 1 and plug 2 as a whole from the bottom crossbar. The bottom crossbar is left below the precast beam. (6) When the zigzag precast concrete roof truss is precast in layers, the bottom crossbar forms a uniform gap between the upper and lower beams, which not only avoids the concrete from sticking together between the upper and lower beams, but also allows the hoisting rope to pass through the gap between the two beams for hoisting.

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