Combined beam concrete roof with hollow tube shear member and anti-cracking construction method

Abstract

The application provides a composite beam concrete roof with a hollow pipe shear member and a crack-resistant construction method. The hollow pipe shear member is used for connecting a steel beam and a concrete roof. The shear connecting member can be bent in two directions through orthogonal circular holes in the middle of the pin rod, releases the deformation constraint between the concrete roof and the steel beam flange, improves the crack resistance of the concrete roof, and has firm anti-pulling effect, which can prevent the separation of the concrete roof and the steel beam. The construction method requires equipment including a hollow pipe shear connecting member, a lifting ring anchoring member, a steel beam, a steel wire rope and a through-type jack. The pre-compression stress is applied to the concrete roof to enhance the crack resistance of the roof. The construction method is simple, the equipment requirement is low, the through-type jack, the cable and the lifting ring can be used repeatedly, and the economic benefit is high. The hollow pipe shear connecting member has simple structure, convenient material selection, low material cost and strong engineering applicability, and has good application prospect.

Description

Technical Field

[0001] This invention relates to the field of composite structure bridge engineering technology, and in particular to the concrete top slab of a composite beam with hollow tube shear members and a crack-resistant construction method. Background Technology

[0002] In continuous composite beam bridges, the common cross-sectional structure consists of steel beams and a concrete top slab, connected by traditional pin connectors, and the entire structure bears the load as a whole. However, under load, the concrete top slab at the pier top experiences tensile force, while the steel beam experiences compressive force. The pins firmly connect the steel beam and the concrete top slab, preventing slippage. In this case, the pins bear significant shear force. When the tensile force on the concrete top slab exceeds the standard value of concrete tensile strength, the top slab is prone to cracking, affecting the durability of the structure.

[0003] To solve this problem, there are two main approaches. One approach is to apply prestress to the concrete top slab at the support location of the continuous bridge to offset the tensile stress generated under the load. The drawback is that the construction process is complex and increases the construction cost, and the equipment cannot be reused. The other approach is to wrap the shear members with materials such as rubber or foam to release the strong constraint between the concrete top slab and the steel beam through deformation. However, the disadvantage is that it requires the addition of elastic materials, special equipment for processing, and is easily disturbed during construction.

[0004] Therefore, this invention proposes a novel hollow tube shear connector and a construction method that is convenient and economical to prevent cracking of the concrete top slab. This method not only improves the durability of composite structure bridges, but also allows for the reuse of construction equipment, resulting in good economic efficiency and fast construction speed. Summary of the Invention

[0005] Technical Objective: To address the aforementioned technical problems, this invention proposes a composite beam concrete slab with hollow tube shear members and a crack-resistant construction method. This method not only introduces sufficient compressive stress into the concrete slab, effectively reducing the tensile stress and enhancing its crack resistance, but also features a simple and efficient on-site construction method, reliable construction quality, reusable construction equipment, and compliance with low-carbon design requirements.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] The composite beam concrete top slab with hollow tube shear members according to the present invention includes: hollow tube shear connectors, which are used to be arranged on the upper flange of the steel beam at the pier position;

[0008] Before the pouring of the tension concrete top slab at the top of the steel beam at the pier location, the hollow tube shear connector is arranged on the upper flange of the steel beam, and the lifting ring anchor is symmetrically installed at both ends of the lower flange plate of the steel beam and the pier concrete.

[0009] One end of the wire rope is connected to the lifting ring anchor of the lower flange of the steel beam, and the other end is connected to the lifting ring anchor of the pier.

[0010] Before pouring the concrete top slab in the tension zone, the through-hole jack is placed between the steel wire ropes of the steel beam lifting ring anchor and the pier lifting ring anchor. The through-hole jack is used to apply tension to the steel wire ropes, causing the steel beam to arch and deform elastically. After the concrete top slab of the pier is poured and the strength meets the design requirements, the through-hole jack is released, and the steel beam rebounds and deforms, generating pre-compression stress on the concrete top slab.

[0011] According to the present invention, a composite beam concrete top slab with hollow tube shear members is provided. The hollow tube shear connector includes a nail head and a nail rod for connecting the steel beam and the concrete top slab. The nail rod is a hollow tube and has two orthogonal holes formed by machining. The bottom end of the nail rod is vertically welded to the top of the negative moment steel beam of the composite beam, and the top end of the nail rod is connected to the nail head.

[0012] According to the present invention, in a composite beam concrete slab with hollow tube shear members, the nail rods are made of low-yield-point steel with a yield strength between 200 MPa and 300 MPa. The diameter d1 of the orthogonal holes is 1 / 5 to 1 / 2 of the nail rod diameter d0, and there are two of them. The inner diameter d2 of the hollow tube is 1 / 5 to 3 / 5 of the nail rod diameter d0. The position of the orthogonal holes should be determined by finite element calculation based on the safety level of the concrete slab and the expected slip deformation x. The diameter d3 of the nail head is capable of resisting separation and lifting between the concrete slab and the steel beam.

[0013] According to the present invention, in a composite beam concrete top slab with hollow tube shear members, the lifting ring anchor is provided with a lifting ring hole for connecting to one end of the wire rope.

[0014] According to the present invention, in the composite beam concrete top slab with hollow tube shear members, the bolts of the lifting ring anchor are connected to the lower flange holes of the steel beam by nuts and washers, and the bolts of the lifting ring anchor are welded to the reinforcing bars in the pier concrete. The lifting ring and bolts are determined according to the design tension of the cable, and the design tension of the cable is determined by the preload required by the structure.

[0015] The present invention discloses a method for crack-resistant construction of a composite beam concrete top slab with hollow tube shear connectors. During construction, a certain number of hollow tube shear connectors are first vertically welded to the upper flange of the steel beam at the pier top. Then, the lifting ring anchors are symmetrically installed at both ends of the lower flange plate of the steel beam and the concrete of the pier. One end of a steel wire rope is connected to the lifting ring anchor of the lower flange of the steel beam, and the other end is connected to the lifting ring anchor of the pier.

[0016] Since the concrete slab and steel beam are connected by hollow tube shear connectors, the steel beam does not constrain the compressive deformation of the concrete slab. By changing the tension value of the through-hole jack, the axial deformation of the concrete slab can be controlled. If the crack resistance of the concrete slab is high, the tension of the through-hole jack can be increased to dynamically control the crack resistance.

[0017] The specific steps of the construction method are as follows:

[0018] S1. Based on the displacement calculation value under the action of tensile force on the concrete top slab at the pier, design the inner and outer diameters of the hollow tube of the nail rod and the position of the orthogonal hole;

[0019] S2. Orthogonal holes are formed in the nail rod at the factory through machining.

[0020] S3. Before pouring the tension concrete top slab at the top of the steel beam at the pier location, arrange the hollow tube shear connector on the upper flange of the steel beam, and symmetrically install the lifting ring anchors on the left and right sides of the lower flange plate of the steel beam and the pier concrete.

[0021] S4. One end of the wire rope is connected to the lifting ring anchor of the lower flange of the steel beam, and the other end is connected to the lifting ring anchor of the pier.

[0022] S5. Before pouring the concrete top slab in the tension zone, the through-hole jack is placed between the steel wire ropes of the steel beam lifting ring anchor and the pier lifting ring anchor. The through-hole jack is used to apply tension to the steel wire ropes, causing the steel beam to arch and undergo elastic deformation.

[0023] S6. After the concrete slab at the top of the pier is poured and the strength meets the design requirements, release the through-hole jack. The steel beam will rebound and deform, generating pre-stress on the concrete slab.

[0024] Beneficial effects:

[0025] (1) When the hollow tube shear connector of the present invention is used in a composite beam bridge, the shear connector can deform under pressure, release the constraint between the steel beam and the concrete top plate, thereby reducing the tensile stress generated in the concrete top plate, preventing cracking of the concrete top plate, and improving the durability of the composite structure.

[0026] (2) The composite beam concrete top plate anti-crack construction method of the present invention can be used in composite beam bridges to realize the introduction of axial pressure on the concrete top plate at the pier, and provide a certain compressive stress reserve for the bridge deck in the negative bending moment zone when the bridge is completed. Moreover, the compressive stress level can be controlled by the tension construction of the through-hole jack, thereby effectively offsetting the tensile force generated by the concrete top plate in the negative bending moment zone under the action of shrinkage, creep and moving load.

[0027] (3) The hollow tube shear connector has the same pull-out resistance as the traditional pin connector, which can prevent the concrete top slab from separating from the steel beam.

[0028] (4) This construction method does not require additional building materials. The lifting ring anchors, wire ropes and through-hole jacks used in construction can be reused, which reduces construction costs and makes construction simple and fast.

[0029] (5) The present invention provides a method for constructing a composite beam concrete top slab with hollow tube shear members to resist cracking. This method can introduce sufficient compressive stress into the concrete top slab of a continuous beam bridge pier, thereby offsetting the tensile stress generated in the concrete top slab during the use of the bridge. This ensures that the bridge deck is under pressure under normal use, prevents the concrete top slab from cracking, improves the durability of the bridge, and the construction equipment is simple, efficient, reusable, and economical. Attached Figure Description

[0030] Figure 1 A schematic diagram of the top of a bridge pier using a composite structure with hollow tube shear connectors;

[0031] Figure 2 This is a schematic diagram of step one of the construction method for crack-resistant concrete top slab of composite beam according to the present invention;

[0032] Figure 3 This is a schematic diagram of step two in the construction method for crack-resistant concrete top slab of composite beam according to the present invention;

[0033] Figure 4 This is a schematic diagram of step three in the construction method for crack-resistant concrete top slab of composite beam according to the present invention;

[0034] Figure 5 This is a schematic diagram of step four in the construction method for crack-resistant concrete top slab of composite beam according to the present invention;

[0035] Figure 6 This is a schematic diagram of step five in the construction method for crack-resistant concrete top slab of composite beam according to the present invention.

[0036] Explanation of reference numerals in the attached drawings: 1-Hollow tube shear connector; 11-Nail head; 12-Nail rod; 121-Orthogonal hole; 2-Steel beam; 21-Upper flange; 22-Web plate; 23-Lower flange; 3-Concrete top plate; 4-Lifting ring anchor; 41-Nut; 42-Bolt; 5-Wire rope; 6-Through-type jack; 7-Concrete pier. Detailed Implementation

[0037] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] The following description, with reference to the accompanying drawings, illustrates a composite beam concrete roof slab with hollow tube shear members, according to an embodiment of the present invention:

[0039] like Figure 1 , Figure 2 The image shows a composite beam concrete top slab with hollow tube shear members as described in this invention, comprising: a hollow tube shear connector 1; a steel beam 2 consisting of an upper flange 21, a web 22, and a lower flange 23; the hollow tube shear connector 1 is used to be arranged on the upper flange 21 of the steel beam 2 at the pier 7 position.

[0040] The hollow tube shear connector 1 includes a nail head 11 and a nail rod 12, which are used to connect the steel beam 2 and the concrete top slab 3. The nail rod 121 is a hollow tube and has two orthogonal holes 121 formed by machining. The bottom end of the nail rod 12 is vertically welded to the top of the steel beam 2 in the negative bending moment zone of the composite beam, and the top end of the nail rod 12 is connected to the nail head 11.

[0041] It should be noted that the nail rod 12 is made of low yield point steel, with a yield strength between 200MPa and 300MPa. The diameter d1 of the two orthogonal holes 121 is 1 / 5 to 1 / 2 of the diameter d0 of the nail rod 121, and the inner diameter d2 of the hollow tube is 1 / 5 to 3 / 5 of the diameter d0 of the nail rod 12. The position of the orthogonal holes 121 should be determined based on the safety level of the concrete top slab 3 and the expected slip deformation x. The diameter d3 of the nail head 11 is sufficient to resist separation and lifting between the concrete top slab 3 and the steel beam 2.

[0042] like Figure 2-3 As shown: Before pouring the tension concrete top plate 3 on the top of the steel beam 2 at the pier 7 position, the hollow tube shear connector 1 is arranged on the upper flange 21 of the steel beam 2, and the lifting ring anchor 4 is symmetrically set at both ends of the lower flange plate 23 of the steel beam 2 and the concrete of the pier 7.

[0043] The lifting eye anchor 4 is connected to the concrete pier 7 by bolts 42, which are welded to the longitudinal reinforcement in the pier 7. The anchorage length l of the bolt 42 in the pier 7 is not less than 10 times the diameter d of the bolt 42. The dimensions of the lifting eye anchor 4, bolt 42, and nut 41 are determined according to the design tension of the wire rope 5.

[0044] The lifting ring anchor 4 is connected to the lower flange 23 of the steel beam 2 by bolts 42. The lower flange 23 of the steel beam 2 is provided with screw holes for installing the bolts 42. The bolts 42 of the lifting ring anchor 4 are connected to the holes of the lower flange 23 of the steel beam 2 by nuts 41 and washers. The bolts 42 of the lifting ring anchor 4 are also welded to the reinforcing bars in the concrete of the bridge pier. The diameter of the lifting ring and bolts is determined according to the design tension of the wire rope 5.

[0045] The two ends of the through-type jack 6 are respectively equipped with steel wire ropes 5; the steel wire rope 5 at one end of the through-type jack 6 is connected to the lifting ring anchor 4 of the lower flange 23 of the steel beam 2; the steel wire rope 5 at the other end of the through-type jack 6 is connected to the lifting ring anchor 4 of the steel beam on the pier 7.

[0046] After the lifting ring anchor 4 is securely installed, the through-hole jack 6 is deployed to apply eccentric pressure F to the steel beam 2. The wire rope 5 at one end of the through-hole jack 6 is connected to the lifting ring anchor 4 on the lower flange 23 of the steel beam 2; the wire rope 5 at the other end of the through-hole jack 6 is connected to the steel beam lifting ring anchor 4 on the pier 7.

[0047] The through-hole jack 6 applies tension to the steel wire rope 5 through the oil pump, causing the steel beam 2 to be eccentrically compressed. The upper flange 21 of the steel beam arches upward with a certain elastic deformation x1, where x1≥x0, and x0 is the displacement of the concrete top slab at the pier under external load or temperature.

[0048] like Figure 4 , Figure 5 , Figure 6 As shown, a method for crack-resistant construction of a composite beam concrete roof slab with hollow tube shear members is as follows: The steps are as follows:

[0049] S1. Calculate the displacement value x of the concrete top plate at 7 piers under tensile force according to the finite element method, and design the inner diameter d1 and outer diameter d0 of the hollow tube of nail rod 12 and the diameter d2 of the orthogonal hole 121.

[0050] S2. Orthogonal holes 121 are formed on the nail rod 12 by machining in the factory;

[0051] S3. Before pouring the tension concrete top plate 3 on the top of the steel beam 2 at the pier 7 position, arrange the hollow tube shear connector 1 on the upper flange 21 of the steel beam 2, and symmetrically set the lifting ring anchor 4 on the left and right sides of the lower flange plate 23 of the steel beam 2 and the concrete of the pier 7.

[0052] S4. One end of the wire rope 5 is connected to the lifting ring anchor 4 of the lower flange 23 of the steel beam 2, and the other end is connected to the lifting ring anchor of the pier 7.

[0053] S5. Before pouring the concrete top slab 3 in the tension zone, the through-hole jack 5 is placed between the steel wire rope 5 of the steel beam 2 lifting ring anchor 4 and the bridge pier 7 lifting ring anchor 4. The through-hole jack 6 is used to apply tension to the steel wire rope 5, so that the steel beam 2 will undergo arching elastic deformation.

[0054] S6. After the concrete slab at the top of the pier is poured and the strength meets the design requirements, release the through-hole jack. The steel beam 2 will rebound and deform, generating pre-stress on the concrete slab 3.

[0055] Since the concrete slab 3 and the steel beam 2 are connected by a hollow tube shear connector, the steel beam 2 does not constrain the compressive deformation of the concrete slab 3. By changing the tension value of the through-hole jack, the axial deformation of the concrete slab can be controlled. If the crack resistance of the concrete slab is high, the tension of the through-hole jack can be increased to dynamically control the crack resistance.

[0056] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A crack-resistant construction method for a composite beam concrete top slab with hollow tube shear members, characterized in that, The composite beam concrete top slab with hollow tube shear members includes: hollow tube shear connectors (1), steel beam (2) and concrete top slab (3) cast on the upper flange (21) of steel beam (2), the concrete top slab (3) being located in the negative bending moment zone of continuous beam pier (7); a plurality of hollow tube shear connectors (1) are provided on the upper flange (21) of steel beam (2) along the length direction of steel beam (2), the hollow tube shear connectors (1) being used to connect steel beam (2) and concrete top slab (3); A tension device for applying prestress is provided between the lower flange (23) of the steel beam (2) located at the pier (7) and the pier (7); The hollow tube shear connector (1) includes a nail head (11) and a nail rod (12); the bottom end of the nail rod (12) is vertically welded to the upper flange (21) of the steel beam (2), and the top end of the nail rod (12) is connected to the nail head (11); The nail rod (12) is a hollow tube with holes (121) in the radial direction of the nail rod (12); there are two holes (121), the central axes of the two holes (121) are arranged orthogonally, and the two holes (121) are arranged vertically and staggered. The construction method includes the following steps: S1. Calculate the displacement of the concrete top slab at pier (7) under tensile force using the finite element method. x Design the inner diameter of the hollow tube shear member of the nail rod (12). d 1 and outer diameter d 2 And the location of the hole (121); S2. A hole (121) is formed in the nail rod (12) by mechanical processing. S3. Before pouring the tensile concrete top plate (3) on the top of the steel beam (2) at the pier (7) position, arrange the hollow tube shear connector (1) on the upper flange (21) of the steel beam (2), and symmetrically set the lifting ring anchor (4) on the left and right sides of the lower flange (23) of the steel beam (2) and the concrete of the pier (7). S4. Connect one end of the wire rope (5) to the lifting ring anchor (4) of the lower flange (23) of the steel beam (2), and connect the other end to the lifting ring anchor (4) of the pier (7). S5. Before pouring the concrete top slab (3) in the tension zone, a through-hole jack (6) is placed between the steel wire rope (5) of the lifting ring anchor (4) of the steel beam (2) and the pier (7). The through-hole jack (6) is used to apply tension to the steel wire rope (5) so that the steel beam (2) is eccentrically compressed and arched elastically deformed. S6. Keep the steel beam in an arched state, support the formwork and pour the top slab concrete. After the concrete top slab of the pier is poured and the strength meets the design requirements, release the tension of the through-hole jack. The steel beam (2) will rebound and deform, generating pre-stress on the concrete top slab (3). When the concrete top slab (3) is subjected to tension, it is necessary to balance part of the pre-stress first, thereby effectively improving the crack resistance of the top slab.

2. The crack-resistant construction method for the composite beam concrete top slab with hollow tube shear members according to claim 1, characterized in that: The tensioning device for applying prestress includes a lifting ring anchor (4), a steel wire rope (5), and a through-hole jack (6); the tensioning device is located on both sides of the pier (7) and is arranged symmetrically. The lifting ring anchors (4) are respectively fixed on the lower flange (23) of the steel beam (2) and the pier (7); the two ends of the through-type jack (6) are respectively provided with steel wire ropes (5); the steel wire rope (5) at one end of the through-type jack (6) is connected to the lifting ring anchor (4) on the lower flange (23) of the steel beam (2); the steel wire rope (5) at the other end of the through-type jack (6) is connected to the lifting ring anchor (4) on the pier (7).

3. The crack-resistant construction method for the composite beam concrete top slab with hollow tube shear members according to claim 1, characterized in that: The lifting ring anchor (4) of the steel beam is connected to the lower flange (23) of the steel beam (2) by bolts (42), and the lower flange (23) of the steel beam (2) is provided with screw holes for installing the bolts (42); The lifting ring anchor (4) of the pier is connected to the pier (7) by bolts (42), which are welded to the longitudinal steel bars in the pier (7).

4. The crack-resistant construction method for the composite beam concrete top slab with hollow tube shear members according to claim 1, characterized in that: The diameter of the hole (121) is 1 / 5 to 1 / 2 of the diameter of the nail rod (12), and the inner diameter of the hollow tube of the nail rod (12) is 1 / 5 to 3 / 5 of the outer diameter of the hollow tube of the nail rod (12).

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