CN112523515B

CN112523515B - Construction method of pre-bent laminated wood-concrete composite beam

Info

Publication number: CN112523515B
Application number: CN202110063690.5A
Authority: CN
Inventors: 徐云; 王雪娇
Original assignee: North China University of Water Resources and Electric Power
Current assignee: North China University of Water Resources and Electric Power
Priority date: 2021-01-18
Filing date: 2021-01-18
Publication date: 2022-03-08
Anticipated expiration: 2041-01-18
Also published as: CN112523515A

Abstract

A construction method of a pre-bent laminated wood-concrete composite beam comprises the following steps: a. selecting a bent glued wood beam as an embedded stiff skeleton of the composite beam; b. drilling a plurality of holes in the center line of the bent glued wood beam, penetrating steel strands in the drilled holes, and installing extrusion heads at the tail ends of the steel strands at the bottom of the glued wood beam; c. fixing the bent glued wood beam arch downwards, installing an upper support frame on the upper part of the bent glued wood beam, and fixedly connecting the upper support frame with the bent glued wood beam; d. concentrating the end of the steel strand penetrated by the bent glued wood beam in the step b on a tool anchor; e. a counterforce device is arranged between the top of the upper support frame and the tool anchor; f. formally pre-bending, namely loading counter force step by step through a counter force device until the glued wood beam reaches a horizontal state without camber and deflection; g. pouring first-stage concrete; h. and releasing the pre-bending force after the strength of the first-stage concrete reaches 95%, and pouring second-stage concrete. The invention has simple construction process and strong operability.

Description

Construction method of pre-bent laminated wood-concrete composite beam

Technical Field

The invention relates to the field of building and bridge engineering, in particular to a construction method of a pre-bent laminated wood-concrete composite beam.

Background

The pre-bent composite beam is a novel composite structure system developed by combining the characteristics of a steel reinforced concrete structure and partial prestressed concrete, and has been widely applied to house construction, ports, bridges and underground engineering in countries such as Europe, America and Japan after years of research and practice since the invention was first invented in 1949. Along with the rapid improvement of national economic level, scientific and technological innovation is vigorously advocated in recent years, the design and construction technology of the pre-bending composite beam is also greatly developed, but an insurmountable gap still exists from large-scale application, and the method mainly comprises the following steps: large steel consumption, relatively high cost of single span, complex construction process and the like.

Disclosure of Invention

The traditional construction process of the steel-concrete pre-bent composite beam mainly comprises two modes of single-beam bending and double-beam bending simultaneous loading and prepressing, and the construction of the composite beam is completed by relying on pre-bending force applying equipment, and the construction equipment and the construction process flow are very complicated, so that the bottleneck problem of hindering the development of the pre-bent composite beam in China is solved.

The invention aims to provide a novel construction method of a pre-bent laminated wood-concrete composite beam, which organically combines a prestressed tendon tensioning technology and a novel laminated wood material by referring to a prestressed concrete construction process, simplifies the original construction method in a unique way and makes the construction and manufacture of the pre-bent laminated wood-concrete composite beam possible.

The purpose of the invention is realized by the following technical scheme:

a construction method of a pre-bent laminated wood-concrete composite beam comprises the following steps:

a. selecting a bent glued wood beam as an embedded stiff skeleton of the composite beam;

b. drilling a plurality of holes in the center line of the bent glued wood beam, penetrating steel strands in the drilled holes, and installing extrusion heads at the tail ends of the steel strands at the bottom of the glued wood beam;

c. fixing the bent glued wood beam arch downwards, installing an upper support frame on the upper part of the bent glued wood beam, and fixedly connecting the upper support frame with the bent glued wood beam;

d. c, concentrating the end part of the steel strand penetrated by the bent glued wood beam in the step b on a tool anchor at the top of the upper support frame;

e. a counterforce device is arranged between the top of the upper support frame and the tool anchor;

f. formally pre-bending, namely loading counter force step by step through a counter force device until the glued wood beam reaches a horizontal state without camber and deflection;

g. pouring first-stage concrete, installing a concrete template, then pouring the concrete, embedding most of the glued wood beam and the extrusion head at the bottom of the glued wood beam in the first-stage concrete, wherein the height of the concrete is more than half of the height of the glued wood beam;

h. and after the strength of the first-stage concrete reaches 95%, releasing the pre-bending force, fastening an extrusion head on the steel strand at the upper part of the glued wood beam, shearing the steel strand at the upper part of the glued wood beam, pouring second-stage concrete, and maintaining to finish the manufacture of the pre-bent glued wood-concrete composite beam.

According to the construction method of the pre-bent laminated wood-concrete composite beam, after the strength of the second-stage concrete meets the requirement, the upper support frame is detached, and the redundant laminated wood beam parts at two ends are subtracted, so that the pre-bent laminated wood-concrete composite beam is obtained.

In the construction method of the pre-bent laminated wood-concrete composite beam, the bent laminated wood beam selected in the step a is an I-shaped section laminated wood beam/rectangular section laminated wood beam.

According to the construction method of the pre-bent laminated wood-concrete composite beam, the water content of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam is less than 12%, the outer layer of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam is coated with waterproof paint, and carbon fiber cloth is pasted on the upper surface and the lower surface of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam.

In the construction method of the pre-bent laminated wood-concrete composite beam, the drilling positions on the bent laminated wood beam in the step b are uniformly distributed on the bent laminated wood beam.

According to the construction method of the pre-bent laminated wood-concrete composite beam, in the step b, the drilling positions on the bent laminated wood beam are respectively the cross section center lines at the beam lengths of 2L/8, 3L/8, 4L/8, 5L/8 and 6L/8.

In the construction method of the pre-bent laminated wood-concrete composite beam, in the step b, after the hole is drilled in the bent laminated wood beam, the adhesive is coated around the drilled hole.

In the step h, after the strength of the first-stage concrete reaches 95%, an extrusion head at the upper part of the pre-bent glued wood beam is fastened, the steel strands are cut off step by step, the template is removed, the pre-bent glued wood beam with the first-stage concrete is turned over by 180 degrees to enable the arch crown to face upwards, then the template is installed, and second-stage concrete is poured to complete the construction of the pre-bent glued wood-concrete combined beam.

By adopting the technical scheme, the invention has the beneficial effects that:

the invention relates to a construction process based on two combined structure beams: one is to use the pouring process of the first-stage concrete and the second-stage concrete of the traditional I-shaped section steel beam/rectangular section steel beam-concrete pre-bending combination beam for reference; the other is a prestressed tension process for the reference of prestressed concrete construction. By organically combining the two processes with the new material, the original construction equipment and construction process are greatly simplified, and a design scheme with simple construction process and strong operability is provided for the construction of the I-shaped section pre-bent laminated wood-concrete composite beam and the construction of the rectangular section pre-bent laminated wood-concrete composite beam.

Drawings

Fig. 1 is a schematic pre-bending view of an i-section curved laminated timber beam according to the present invention.

Fig. 2 is a left side view of fig. 1.

Fig. 3 is a schematic structural view of a pre-bent glued wood beam with an I-shaped section.

Fig. 4 is a left side view of fig. 3.

Fig. 5 is a schematic diagram of a steel strand arrangement.

Fig. 6 is a schematic view of a first-stage concrete pouring position of the I-shaped section laminated wood beam.

Fig. 7 is a left side view of fig. 6.

Fig. 8 is a schematic view of a laminated wood beam-concrete composite beam of i-shaped section pre-bent after first-stage concrete.

Fig. 9 is a left side view of fig. 8.

Fig. 10 is a schematic view of a second-stage concrete post-preflex laminated wood-concrete beam with an i-section.

Fig. 11 is a left side view of fig. 10.

Fig. 12 is a schematic pre-bending view of a rectangular cross-section curved laminated wood beam of the present invention.

Fig. 13 is a schematic view of a pre-bent rectangular cross-section laminated wood beam structure.

Fig. 14 is a schematic view of a rectangular-section laminated wood beam in concrete pouring in one stage.

Fig. 15 is a schematic view of a rectangular cross-section laminated wood beam-concrete composite beam pre-bent after first stage concrete.

Fig. 16 is a schematic view of a post-pre-curved rectangular cross-section laminated wood-concrete composite beam of the present invention.

Fig. 17 is a view of construction equipment for a pre-bent laminated wood-concrete composite beam according to the present invention.

Fig. 18 is a left side view of fig. 17.

Detailed Description

The structure and operation of the present invention will be described in detail below with reference to fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6, fig. 7, fig. 8, fig. 9, fig. 10, fig. 11, fig. 12, fig. 13, fig. 14, fig. 15, and fig. 16.

Example 1

As shown in fig. 1 to 10, a construction method of a pre-bent laminated wood-concrete composite beam, which is a construction method of a pre-bent laminated wood-concrete composite beam with an i-shaped cross section in the present embodiment, includes the following steps:

a. selecting a bent I-shaped section laminated wood beam 18 as an embedded stiff skeleton of the composite beam: compared with an I-shaped section steel beam, the laminated wood beam has simpler manufacturing process and cost in design, material taking, processing and other aspects, replaces welding with a gluing mode, and can effectively reduce the problems of stress concentration, fatigue damage and the like caused by welding seams. Because the I-shaped section timber beams can be designed into different spans according to the size of the flange, the I-shaped section timber beams have more selectivity and flexibility. In consideration of the pre-stressing and load-bearing functions of the wooden beams in the whole composite beam, the web and the flange of the I-shaped section laminated wooden beam are both selected to be structural composite material LVL (laminated veneer lumber) with higher strength. Enough process margin is reserved in the length design of the glued wood beam, and the purpose is to prevent the reverse deformation in the manufacturing process of the pre-bent composite beam. The original water content of the wooden beam can be greatly changed by pouring the concrete, the strength of the glued wooden beam is directly influenced, therefore, after the original glued wooden beam is processed, the water content of the glued wooden beam is strictly controlled to be below 12%, and 3 layers of waterproof paint are coated to block the invasion of water. Considering that the concrete can reach the target strength after about 20 days, and the tensile side of the wood beam is very easy to be broken in the process, the carbon fiber cloth 17 needs to be adhered to the upper side and the lower side of the wood beam in the process of tensioning so as to enhance the tensile strength of the whole wood beam and ensure the integrity of the beam body and the construction safety in the whole tensioning process.

b. Uniformly drilling a plurality of holes in the center line of the bent glued wood beam, penetrating steel strands 7 in the drilled holes, and installing extrusion heads at the tail ends of the steel strands at the bottom of the glued wood beam; in the experiment, the specific positions of the drill holes were as follows: drilling holes at the center lines of an upper flange 16 and a lower flange 15 at two sides of an I-shaped section glued wood beam web 14 with sections of 2L/8, 3L/8, 4L/8, 5L/8 and 6L/8 for calculating the beam length, installing steel strands 7 in the drilling holes at the positions of 2L/8, 3L/8, 4L/8, 5L/8 and 6L/8 in the middle, and installing extrusion heads 8 at the tail ends of the steel strands at the bottom of the wood beam. Holes are drilled at the two ends of the bent glued wood beam to be used as counter-force supports, and holes are preferably drilled at the positions, 1L/8 and 7L/8 of the calculated beam length, of the bent glued wood beam to be used as counter-force supports. Before the pre-bending force is applied, the relative position of the perforated point and the central line of the beam needs to be checked carefully, and the camber and the lateral bending radian of each control section are measured again, so that the allowable deviation is as follows: the mid-span camber is less than 8mm, and the mid-span lateral curvature is less than 3mm, as shown in fig. 1, in order to prevent the beam body from being stressed eccentrically to cause transverse instability.

c. The bent I-shaped section laminated wood beam is fixed with the arch facing downwards, an upper support frame is arranged at the upper part of the bent laminated wood beam, and the upper support frame is fixedly connected with the bent laminated wood beam; the bent glued wood beam is fixed, and the opening on the bent glued wood beam can generate stress concentration, so that the local stress redistribution of the flange part is caused, therefore, the adhesive is coated at the junction of the steel strand and the opening of the flange, the stress loss caused by the opening can be effectively compensated, and the occlusion degree of the steel strand and the opening of the flange is greatly improved. The pre-bending force applied by the hydraulic jack transfers the load to the counter-force supporting structure through the steel strand and the extrusion head, and then primary positioning and fixing of the glued wood beam are completed (as shown in figures 1 and 2).

f. and (4) pressure testing, namely testing the pressure of the bent glued wood beam before formal pre-bending so as to eliminate residual deformation in the bent glued wood beam. After comprehensive inspection is carried out, the pre-bending force can be loaded step by step after the extrusion heads, the reverse support positions and the acting force meet the requirements are determined; checking the actual pre-bending force by controlling the final downwarping amplitude of the midspan section, and observing the transverse displacement and transverse support stress conditions of the glued wood beam at any time in the loading process; and when the deflection of the glued wood beam meets the requirement, recording the actual pre-bending force, then unloading step by step, and finally measuring the residual deflection.

And (3) performing formal pre-bending, namely loading counter force step by step through a counter force device until the glued wood beam reaches a horizontal state without camber and deflection, namely pre-bending the glued wood beam 19 with the I-shaped section without camber, controlling according to the deflection value of the wood beam in the loading process, and reloading the pre-bending force when the deflection value reaches a design value and the difference of actual stress force exceeds 5%, as shown in figures 3 and 4.

In the case of the stepwise applied reaction force, as shown in fig. 5, the distance between the reaction point and the dome of the curved laminated wood beam (i.e., the midpoint of the curved laminated wood beam) is d1, the distance between the reaction point and the nearest drill holes on both sides of the dome of the curved laminated wood beam is d2, the distance between the reaction point and the slightly distant drill holes on both sides of the dome of the curved laminated wood beam is d3, the first steel strand in the midpoint of the curved laminated wood beam is in a straightened state, and the length L1= d1,

a second steel strand is arranged below the steel strand on the nearest drill holes on two sides of the middle, the vertical distance h2 from the reaction point to the second steel strand is less than d1 by delta h1, and the length L2= d2+ delta h1 of the second steel strand; the steel strand on the drill hole slightly far away from the two sides in the middle is a third steel strand, the vertical distance h3 from the reaction point to the third steel strand is less than d1 by delta h2, and the length L3= d3+ delta h2 of the third steel strand.

When primary counter-force loading is carried out, the first steel strand is pulled to be lifted upwards to the position flush with the drill hole corresponding to the second steel strand, and the second steel strand is just straightened; carrying out secondary counter-force loading, wherein the first steel strand and the second steel strand are uniformly subjected to upward tension, the arch crown of the bent glued wooden beam and the symmetrical positions at two sides of the arch crown are uniformly subjected to upward tension, and the third steel strand is just straightened until the bent glued wooden beam is pulled to be level with the drill hole corresponding to the third steel strand; and carrying out three-stage counter-force loading, wherein the first steel strand, the second steel strand and the third steel strand are all subjected to upward pulling force until the bent glued wood beam is flattened to reach an arch-free state.

g. Pouring first-stage concrete, installing a concrete template, then pouring the concrete, embedding most of the glued wood beam and the extrusion head at the bottom in the first-stage concrete 12, wherein the height of the concrete exceeds the height of the upper and lower extrusion heads of the lower wing plate and the lower wing plate of the glued wood beam; after determining that the wooden beam has no cracking, transverse instability and the like, a concrete template can be installed, and then concrete above C40 is poured on the lower flange part, wherein the concrete pouring positions are shown in figures 6 and 7. It should be noted that before and during the casting process, the stress conditions of the steel strand and the extrusion head need to be checked repeatedly to avoid the problems of damage to the extrusion head and the steel strand caused by the construction.

h. Releasing the pre-bending force after the strength of the first-stage concrete reaches 95%, checking the combination condition of the wood beam and the concrete after the strength of the first-stage concrete reaches 95% of the design strength, ensuring that no concrete and the local cracking of the wood beam exist, then fastening an extrusion head at the upper part of the wood beam, releasing the pre-bending force step by step, and bearing the pre-pressing force generated by the wood beam on the concrete due to the inverted arch of the wood beam to obtain the inverted arch pre-bent I-shaped section glued wood beam 20; meanwhile, due to the constraint of concrete, the camber of the pre-bent beam is less than the pre-camber value of the original wood beam, as shown in fig. 8 and 9. Then the extrusion head on the steel strand at the upper part of the glued wood beam is fastened, and the steel strand at the upper part of the glued wood beam is cut off.

The gradual releasing pre-bending force is gradually released from two sides to the middle, namely, the steel strands are gradually sheared inwards from two sides of the laminated wood.

i. And (5) pouring second-stage concrete, subtracting the redundant wood beam part and the steel strands from the composite beam in the step h, leaving the residual steel strands and the extrusion heads in the structure, reversely mounting the beam body to enable the arch crown to be upward after the composite beam is conveyed to the spanning position of the construction site, then mounting a template, binding steel bars, pouring second-stage concrete 13, and finishing the construction of the final pre-bent composite beam, as shown in figures 10 and 11.

The I-shaped section pre-bent laminated wood-concrete composite beam is formed by embedding an I-shaped section laminated wood beam in concrete, completely wrapping a lower wing plate of the I-shaped section laminated wood beam in the first-stage concrete by first-stage pouring concrete, then performing second-stage concrete pouring on a web plate and an upper wing plate of the remaining exposed I-shaped section, and completely wrapping the I-shaped section laminated wood beam in the concrete.

Example 2

As shown in fig. 12 to 16, a method for constructing a pre-bent laminated wood-concrete composite beam, which is a method for constructing a pre-bent laminated wood-concrete composite beam with a rectangular cross section, includes the following steps:

a. selecting a bent glued wood beam 21 with a rectangular section as an embedded stiff skeleton of the composite beam: compared with an I-shaped section steel beam, the rectangular section glued wood beam has the advantages that the production process of the original pre-arch I-shaped section steel beam is really reduced from the aspects of designing and manufacturing wood beams with arch degree, span, size and the like, and the problems of stress concentration, fatigue damage and the like of the I-shaped section steel beam caused by welding seams are effectively reduced. The pre-bent glued wood beam plays a role in exerting prestress in the whole composite beam and also plays a role in bearing external load. The wood beam can be selected from structural composite materials with rectangular section, such as LVL (laminated veneer lumber), PSL (parallel strand lumber), LSL (laminated strand lumber) and laminated wood. According to construction drawings and a process, in order to ensure that the camber after manufacturing reaches a design standard, a pre-set anti-deformation measure is considered in the manufacturing process of the glued wood beam, and process allowances are added at two ends of the total length. The strength of the wooden beam depends on the moisture content of wood, and in order to prevent the original moisture content of the glued wooden beam from being changed due to the pouring of concrete in the manufacturing process of the combined beam, the moisture content of the glued wooden beam needs to be strictly controlled below 12%, and 3 layers of waterproof paint need to be coated after the manufacturing is finished, so that the moisture isolation effect is achieved. In the period of about 20 days for the concrete to reach the target strength, the glued wood beam is easy to be stretched and broken at the midspan part, so that carbon fiber cloth needs to be adhered to the upper side and the lower side of the stretched wood beam in the manufacturing process of the wood beam, the tensile strength of the whole glued wood beam is enhanced, and the wood beam is prevented from being broken due to stretching.

b. Uniformly drilling a plurality of holes in the center line of the bent glued wood beam, penetrating steel strands in the drilled holes, and installing extrusion heads at the tail ends of the steel strands at the bottom of the glued wood beam; in the experiment, the specific positions of the drill holes were as follows: in order to be able to apply the pre-bending force evenly, pre-drilling holes at the 2L/8, 3L/8, 4L/8, 5L/8, 6L/8 center lines of the bent glued wood beam for the purpose of installing steel strands is required. Holes are drilled at the two ends of the bent glued wood beam to be used as counter-force supports, and holes are preferably drilled at the positions, 1L/8 and 7L/8 of the calculated beam length, of the bent glued wood beam to be used as counter-force supports. In order to ensure that a stress point is strictly controlled at the central line position of a beam and prevent the transverse instability of the wood beam caused by eccentric stress, the on-site glued wood beam needs to be retested before prebending, and mainly the camber and the lateral curvature radian of each control section are measured to allow deviation: midspan camber is less than 8mm, midspan lateral curvature is less than 3mm, and the location of the web centerline predrilled hole at the control section is identified unambiguously, as shown in fig. 12.

c. Fixing the bent glued wood beam with the arch facing downwards, installing an upper support frame on the upper part of the bent glued wood beam, and fixedly connecting the upper support frame with the bent glued wood beam;

installing steel strands at the opening of the glued wood beam, in order to raise the adhesive force between the steel strands and the glued wood beam, pre-coating adhesive on the contact part of the steel strands and the glued wood beam, collecting 5 steel strands at a hydraulic jack, installing 5 extrusion heads at the bottom of the glued wood beam, applying initial pre-bending force through the jack, and completing the primary positioning and fixing of the glued wood beam by means of the steel strands and a counter-force supporting structure, as shown in fig. 12.

f. and (4) bending test, namely bending test of the glued wood beam, and performing test bending after comprehensively checking and determining that each extrusion head, the reverse support position and the acting force meet the requirements. In order to eliminate residual deformation inside the laminated wood beam, the laminated wood beam is subjected to pressure testing before formal pre-bending, pre-bending force is applied step by step, the final down-bending amplitude of the cross-middle section is controlled, and meanwhile, the actual pre-bending force is checked. The transverse displacement and the transverse support stress condition of the glued wood beam are observed at any time in the stress application process. When the deflection of the glued wood beam meets the requirement, recording the actual pre-bending force, then unloading step by step, and finally measuring the residual deflection and using a level gauge for measuring the deflection.

And (3) performing formal pre-bending, gradually loading counter force through a counter force device, controlling the loading process according to the bending value of the glued wood beam, and performing pre-bending loading again when the bending value reaches the design value and the difference of the actual force application exceeds 5%. As shown in fig. 14 and 15, the pre-bent laminated wood beam 22 having a rectangular section without camber is obtained until the laminated wood pre-bent beam reaches a horizontal state without camber and without deflection.

The method for gradually loading the counterforce is the same as the method for bending the glued beam with the I-shaped section.

g. Pouring first-stage concrete, installing a concrete template, then pouring the concrete, embedding most of the glued wood beam and the extrusion head at the bottom of the glued wood beam in the first-stage concrete, wherein the height of the concrete is more than half of the height of the glued wood beam; after determining that the non-camber laminated wood beam has no cracking, transverse instability and other problems, a concrete template can be installed, and then concrete is poured into high-performance concrete with the concrete content of more than C40 (as shown in FIG. 14).

h. And releasing the pre-bending force after the strength of the first-stage concrete reaches 95%. After the strength and the elastic modulus of the concrete reach 95% of the designed values in the first period, the upper extrusion head of the glued wood beam is fastened, the pre-bending force F is released step by step, the pre-pressing force generated by the glued wood pre-bending beam is applied to the concrete, the whole wood beam restores the partial camber, namely the rectangular-section pre-bent glued wood beam 23, and the reverse camber of the rectangular-section pre-bent glued wood beam 23 is smaller than the pre-camber of the original glued wood beam due to the action of the concrete (as shown in figures 14 and 15).

i. And (5) pouring second-stage concrete, subtracting the redundant wood beam part and the steel strands from the composite beam in the step h, leaving the residual steel strands and the extrusion heads in the structure, reversely mounting the beam body to enable the arch crown to be upward after the composite beam is conveyed to the spanning position of the construction site, then mounting a template, binding steel bars, pouring second-stage concrete, and finishing the construction of the final pre-bent composite beam, as shown in fig. 16.

The rectangular-section pre-bent laminated wood-concrete composite beam is formed by embedding a rectangular-section laminated wood beam in concrete, completely wrapping the lower part of the rectangular-section laminated wood beam in the first-stage concrete by first-stage pouring concrete, then carrying out second-stage concrete pouring on the rest exposed rectangular-section laminated wood beam, and completely wrapping the rectangular-section laminated wood beam in the concrete.

When the pre-bent laminated wood-concrete composite beam is constructed, the pre-bent laminated wood-concrete composite beam construction equipment is used, as shown in figures 17 and 18, and comprises a support frame for fixing the bent laminated wood beam, wherein the support frame is formed by connecting an upper support frame 4 and a lower support frame 6 through bolts 5. Before the upper supporting frame is not installed with the lower supporting frame, a place with a large area needs to be selected according to the design span of the combination beam, the foundation is reinforced and the anchor piles are driven into the foundation, and the four supporting points of the lower supporting frame are fixed on the foundation through anchor bolts. The top of the upper supporting frame is provided with a tool anchor 1, a plurality of steel strands 7 used for penetrating through the bending beam are arranged between the upper supporting frame and the lower supporting frame, one end of each steel strand is provided with two extrusion heads 8, the other end of each steel strand penetrates through the tool anchor and is fixed on the tool anchor, and the top of the tool anchor and the top of the upper supporting frame is provided with a counter-force device 2.

The top of the upper support frame is provided with a limiting plate 3, the top of the upper support frame and the limiting plate are respectively and correspondingly provided with a through hole for the steel strand to pass through, the counter-force device is arranged between the limiting plate and the tool anchor, and the limiting plate is used as a supporting platform of the counter-force device. The lower supporting frame is formed by fixedly connecting a left trapezoid frame, a right trapezoid frame, a front underframe and a rear underframe which are respectively connected with the left trapezoid frame and the right trapezoid frame, the front end and the rear end of the top of the left trapezoid frame and the right trapezoid frame are respectively provided with a platform 9 for mounting bolts, the upper supporting frame is formed by a left triangular frame, a right triangular frame and a top beam, the top of the left triangular frame and the top of the right triangular frame are fixed on the top beam, the front end and the rear end of the left triangular frame and the front end and the rear end of the right triangular frame are respectively provided with a platform for mounting bolts, the bolts respectively penetrate through the platform at the front end of the left triangular frame and the corresponding platform at the front end of the left trapezoid frame to fix the front end of the left triangular frame and the front end of the left trapezoid frame together, and the bolts respectively penetrate through the platform at one end of the left triangular frame and the corresponding platform at the rear end of the left trapezoid frame to fix the rear end of the left triangular frame and the rear end of the left trapezoid frame together; the bolts respectively penetrate through the platform at the front end of the right tripod and the platform at the front end of the corresponding right trapezoid frame to fix the front end of the right tripod and the front end of the left trapezoid frame together, the bolts respectively penetrate through the platform at the rear end of the right tripod and the platform at the rear end of the corresponding right trapezoid frame to fix the rear end of the right tripod and the rear end of the right trapezoid frame together, and the limiting plate is fixed on the top beam.

A field with a larger area is selected according to the design span of the composite beam, the foundation is reinforced and the anchor piles are driven into the foundation, and the four supporting points of the lower supporting frame are fixed on the foundation through the anchor bolts.

The bent laminated wood beam is placed on the lower support frame in an arch-downward manner, and then the upper support frame is fixed on the lower support frame through bolts, so that the bent laminated wood beam is fixed between the lower support frame and the lower support frame. The technological allowance added at the two ends of the length of the glued wood beam extends out of the two sides of the lower supporting frame and the lower supporting frame. A plurality of steel strands are gathered to a hydraulic jack, the steel strands and the pre-bent glued wood beam are fixed through a tool anchor and an extrusion head, initial pre-bending force is applied through the jack, and initial positioning and fixing of the glued wood beam are completed through the steel strands and three structures of 4 platform reaction points on the left and right of an upper support frame structure.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the overall concept of the invention, and these should be considered as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicability of the patent.

Claims

1. A construction method of a pre-bent laminated wood-concrete composite beam comprises the following steps:

c. fixing the bent glued wood beam with the arch facing downwards, installing an upper support frame on the upper part of the bent glued wood beam, and fixedly connecting the upper support frame with the bent glued wood beam; the curved glued wood beam arch faces downwards, namely the curved glued wood beam arch is propped against the lower opening upwards;

h. and releasing the pre-bending force after the strength of the first-stage concrete reaches 95%, fastening an extrusion head on the steel strand at the upper part of the glued wood beam, shearing the steel strand at the upper part of the glued wood beam, pouring second-stage concrete, and curing to obtain the pre-bent glued wood-concrete composite beam.

2. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: and after the strength of the second-stage concrete meets the requirement, removing the upper support frame, and subtracting the redundant glued wood beam parts at two ends to obtain the pre-bent glued wood-concrete combined beam.

3. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: the bent glued wood beam selected in the step a is an I-shaped section glued wood beam/rectangular section glued wood beam.

4. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 3, wherein: the water content of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam is less than 12%, waterproof paint is coated on the outer layer of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam, and carbon fiber cloth is pasted on the upper surface and the lower surface of the bent I-shaped section laminated wood beam/rectangular section laminated wood beam.

5. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: the drilling positions on the bent laminated wood beam are uniformly distributed on the bent laminated wood beam.

6. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: and b, drilling holes on the bent glued wood beam at the cross-section center lines with the beam lengths of 2L/8, 3L/8, 4L/8, 5L/8 and 6L/8 respectively.

7. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: and b, after drilling holes in the bent glued wood beam, coating adhesive around the drilled holes.

8. The construction method of the pre-bent laminated wood-concrete composite beam according to claim 1, wherein: and h, after the strength of the first-stage concrete reaches 95%, fastening an extrusion head at the upper part of the bent glued wood beam, shearing the steel strands step by step, removing the template, turning the pre-bent glued wood beam with the first-stage concrete for 180 degrees to enable the vault to face upwards, then installing the template, pouring second-stage concrete, and completing construction of the pre-bent glued wood-concrete combined beam.