Reinforced concrete-filled steel tube arch, checking calculation method and construction method

Abstract

The invention discloses a reinforced concrete-filled steel tube arch, a checking calculation method and a construction method. The reinforced concrete-filled steel tube arch comprises a steel tube, concrete, an outer steel connecting piece, a reinforcement cage and a suspender, the reinforcement cage comprises transverse reinforcements and longitudinal reinforcements, the transverse reinforcements are vertically arranged along the longitudinal reinforcements at intervals, the reinforcement cage is located in the steel pipe, the outer steel connecting piece is located on the outer side of the steel pipe and arranged corresponding to a to-be-installed suspender, the outer steel connecting piece is fixedly connected with the steel pipe, and the steel pipe is filled with concrete. Shrinkage and creep of concrete can be reduced, the bearing capacity and ductility of the concrete-filled steel tube arch are improved, the fireproof performance is improved, disengaging is reduced, and force transmission is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of structural engineering, and particularly relates to a reinforced steel pipe concrete arch, a checking method and a construction method. BACKGROUND

[0002] The steel pipe concrete arch is an important structural component in bridge engineering, and is usually filled with plain concrete in the steel pipe arch. The component has the advantages of being green and having good seismic performance. However, the following problems exist: 1. The plain concrete is only constrained by the outer steel pipe, and the bearing capacity and ductility are limited, and the redundancy is low; 2. Under the action of fire or explosion load, the bearing capacity and ductility of the plain concrete are poor after the steel pipe is destroyed by heat absorption; 3. The plain concrete is prone to void between the concrete and the side wall of the steel pipe and between the concrete and the steel pipe, and the force transmission and ductility are poor. SUMMARY

[0003] The present application provides a reinforced steel pipe concrete arch, a checking method and a construction method, which solve the technical problems of the traditional steel pipe plain concrete arch, such as limited constraint, poor bearing capacity and ductility, and easy void between the steel pipe and the plain concrete.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions.

[0005] A reinforced steel pipe concrete arch comprises a steel pipe, concrete, an outer steel connecting piece, a steel reinforcement cage and a suspender. The steel reinforcement cage comprises transverse steel reinforcement and longitudinal steel reinforcement, and the transverse steel reinforcement is vertically arranged at intervals along the longitudinal steel reinforcement. The steel reinforcement cage is located in the steel pipe. The outer steel connecting piece is located on the outer side of the steel pipe and is arranged correspondingly to the suspender to be installed. The outer steel connecting piece is fixedly connected with the steel pipe. The concrete fills the steel pipe.

[0006] Preferably, the outer steel connecting piece is a steel plate, and the steel plate is provided with a hole. A bolt is arranged at the hole to connect the suspender with the outer steel connecting piece.

[0007] Preferably, the reinforced steel pipe concrete arch is provided with an inner steel reinforcing piece and / or a stud in the steel pipe. The inner steel reinforcing piece is fixedly connected with the steel pipe, and the inner steel reinforcing piece is a steel reinforcement ring or a steel plate hoop.

[0008] Preferably, the steel reinforcement cage is continuous along the steel pipe arch, and the transverse steel reinforcement is densified or has an increased diameter in the region corresponding to the suspender.

[0009] Preferably, the transverse steel reinforcement is a ring-shaped stirrup or a spiral stirrup.

[0010] Preferably, the steel pipe is provided with an additional steel reinforcement cage, and the additional steel reinforcement cage is located in the steel reinforcement cage.

[0011] Preferably, the reinforced steel pipe concrete arch is provided with longitudinal stiffening ribs in the steel pipe, and the longitudinal stiffening ribs are fixedly connected with the steel pipe as a whole; and the outer steel connecting piece is a ring-shaped steel plate.

[0012] A method for calculating the axial bearing capacity of a reinforced steel pipe concrete arch, comprising the following specific steps:

[0013] Step 1, determining the diameters, numbers, strengths and arrangements of vertical and horizontal steel bars, determining the strength parameters of concrete, determining the sectional geometric dimensions of the steel pipe, the dimensions of the steel or steel plate, and the strength parameters of the steel material;

[0014] Step 2, checking according to the following formula:

[0015] N c

[0016] N c =α[f c ′A c +f a ′A a +f s ′A s +β(f c ′A c )]

[0017] In the formula, N is the design value of the axial force of the reinforced steel pipe concrete arch;

[0018] N c is the design value of the axial bearing capacity of the reinforced steel pipe concrete arch;

[0019] f c ′ is the design value of the compressive strength of concrete;

[0020] f′ a is the design value of the compressive strength of the steel pipe;

[0021] f s ′ is the design value of the compressive strength of the longitudinal steel bar;

[0022] A c is the cross-sectional area of the reinforced steel pipe concrete arch;

[0023] A a is the cross-sectional area of the steel or steel plate of the steel pipe;

[0024] A s is the cross-sectional area of the longitudinal steel bar;

[0025] α is a bearing capacity reduction coefficient, which is determined by considering the factors such as the steel pipe inner wall interface, the concrete strength, the longitudinal steel bar arrangement rate, etc., and is 0.6-1.0;

[0026] β is a bearing capacity reduction coefficient, which is determined by considering the factors such as the steel pipe inner wall interface, the concrete strength, the longitudinal steel bar arrangement rate, etc., and is 0.6-1.0;

[0027] β - concrete constraint effect coefficient, considering the shape of transverse steel bar, distribution interval, shape of steel pipe, thickness of steel pipe, strength of concrete and other factors, taking 0-2.0.

[0028] The strength parameter in the formula is valued according to the existing standard or by experiment, and the geometric parameter is valued according to the actual size or nominal size, and steps 1-2 are repeated, and the axial compression bearing capacity of the arch is compared with the maximum axial compression force calculated by the actual working load of the structure, and the maximum axial compression force is greater.

[0029] A construction method of a reinforced steel pipe concrete arch, the construction steps are as follows:

[0030] Step one, pre-process steel pipe, outer steel connecting piece, inner steel reinforcing piece, stud (if any) in the factory, fixed connection as a whole; according to the need to make vertical steel bar, transverse steel bar, steel cage and / or additional steel cage;

[0031] Step two, first construct the pre-processed steel pipe, and fix it after axial and arc positioning;

[0032] Step three, place the steel cage into the steel pipe, and fix it after axial and arc positioning;

[0033] Step four, then hoist the next section of steel pipe to the side of the already installed steel pipe, align and temporarily fix it, and weld or bolt it to the already installed steel pipe;

[0034] Step five, place the steel cage into the steel pipe, connect with the already installed steel cage, and fix it after calibration and positioning;

[0035] Step six, pour concrete and maintain to the predetermined strength.

[0036] Preferably, the construction method of the reinforced steel pipe concrete arch in step one, the steel pipe and the steel cage and / or additional steel cage are fixedly connected in the factory, and the other construction steps are adjusted accordingly.

[0037] Compared with the prior art, the present application has the following characteristics and beneficial effects.

[0038] 1. The steel cage is placed in the steel pipe to form a multiple-constrained steel pipe concrete component with the steel pipe, and the steel cage can reduce the shrinkage and creep of the concrete, thereby improving the bearing capacity and ductility of the steel pipe concrete component.

[0039] 2. In a fire, when the outer steel pipe loses its bearing capacity, the inner steel cage and concrete form a reinforced concrete arch, which becomes the second line of defense against fire.

[0040] 3. The inner steel connecting piece is a steel bar or a steel plate hoop, which reduces the void and facilitates construction and force transmission.

[0041] 4. The outer steel connector is annular, which is easy to transfer the force from the hanger. BRIEF DESCRIPTION OF DRAWINGS

[0042] The application will be further described below in conjunction with the drawings.

[0043] Figure 1 Fig. 1 is a schematic view of a reinforced steel tube concrete arch facade.

[0044] Figure 2 Fig. 2 is a schematic view of a reinforced steel tube concrete arch section. Figure 1

[0045] Fig. 3 is a schematic view of a reinforced steel tube concrete arch section. Figure 3 Figure 2 Fig. 4 is a schematic view of a reinforced steel tube concrete arch section.

[0046] Figure 4 Figure 3 Fig. 5 is a schematic view of a reinforced steel tube concrete arch section.

[0047] Reference signs: 1 - steel tube, 2 - concrete, 3 - outer steel connector, 4 - steel cage, 5 - transverse steel bars, 6 - longitudinal steel bars, 7 - inner steel reinforcement, 8 - additional steel cage, A - structural column, B - hanger. DETAILED DESCRIPTION

[0048] In order to better understand the purpose, technical solution and function of the present application, the present application will be further described in detail below in conjunction with the drawings. Herein, the illustrative embodiments of the present application and the description thereof are used to explain the present application, but are not intended to limit the present application.

[0049] In the description of the present application, it should be understood that the terms "include / contain", "consist of" or any other variants thereof are intended to cover non-exclusive inclusion, so that the product, device, process or method including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes the elements inherent to such product, device, process or method. Without more limitation, the elements defined by the statement "include / contain", "consist of" do not exclude the presence of other identical elements in the product, device, process or method including the said elements.

[0050] ​​In the present application, unless otherwise explicitly specified and limited, the term "fixed connection" should be understood in a broad sense, for example: it can be sleeve connection, it can be lap joint, it can be welding, it can be bolted connection, it can be a combination of the above connections; the terms "installation", "connection", "connection" and the like should be understood in a broad sense, for example, it can be fixed connection, or it can be detachable connection, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two components or the interaction relationship between two components; the term "longitudinal reinforcement" refers to continuous reinforcement without disconnection, or disconnected reinforcement but fixed connection between the disconnected reinforcement. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] It should also be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices, components or structures referred to must have a particular orientation, be constructed or operated in a particular orientation, and cannot be understood as a limitation on the present application.

[0052] The implementation of the present application is described in detail below with reference to the preferred embodiments in conjunction with the accompanying drawings.

[0053] As shown in Figures 1-4 A reinforced concrete arch pipe is composed of a steel pipe 1, concrete 2, an outer steel connecting piece 3, a reinforcement cage 4, a suspender B, transverse reinforcement 5 and longitudinal reinforcement 6, the reinforcement cage 4 is located in the steel pipe 1, the outer steel connecting piece 3 is located on the outer side of the steel pipe 1 and is arranged correspondingly to the suspender B to be installed, the outer steel connecting piece 3 is fixedly connected with the steel pipe 1, the fixed connection mode is welding, and the concrete 2 is filled in the steel pipe 1.

[0054] The reinforcement cage of the present application is built-in in the steel pipe and forms a multiple-constrained concrete-filled steel pipe member with the steel pipe, which can improve the bearing capacity and ductility of the concrete-filled steel pipe member, and can reduce the shrinkage and creep of the concrete in the steel pipe. In a fire, when the outer steel pipe loses its bearing capacity, the built-in reinforcement cage and concrete form a reinforced concrete arch, which becomes a second line of defense against fire, further improving the performance of the present application.

[0055] In specific implementation, the thickness of the steel pipe is not less than 4mm.

[0056] In specific implementation, the outer steel connecting piece 3 is made of a steel plate, the steel plate is provided with a hole, and the hole is provided with a bolt to connect the suspender and the outer steel connecting piece 3 into one body.

[0057] In specific implementation, as shown in Figure 1 and Figure 3As shown, the steel pipe 1 has inner steel reinforcement 7 and / or studs, the inner steel reinforcement 7 is welded with the steel pipe 1 as a whole, and the inner steel reinforcement 7 is a reinforcing ring or a steel plate hoop or a steel bracket.

[0058] In the specific implementation, the steel reinforcement cage 4 is arranged continuously along the steel pipe arch, and the transverse steel reinforcement 5 is densified or increased in diameter in the region corresponding to the suspender B. The effect is to reduce the shrinkage of the concrete and improve the shear capacity of the region.

[0059] In the specific implementation, the transverse steel reinforcement 5 is a ring-shaped hoop or a spiral hoop. The effect is to further improve the ductility and carrying capacity of the present application.

[0060] In the specific implementation, as shown in Figure 4 The steel pipe 1 has an additional steel reinforcement cage 8 located in the steel reinforcement cage 6. A three or more nested hoop effect is formed to improve the carrying capacity and ductility.

[0061] In the specific implementation, longitudinal stiffening ribs are arranged in the steel pipe 1 and are welded with the steel pipe 1 as a whole. The effect is to improve the buckling resistance of the steel pipe concrete arch.

[0062] In the specific implementation, the outer steel connecting member 3 is a ring-shaped steel plate. The effect is to improve the force transmission performance of the joint.

[0063] A method for calculating the axial load carrying capacity of a reinforced steel pipe concrete arch, the specific steps are as follows:

[0064] Step 1, determine the steel reinforcement diameter, number, strength and arrangement of the vertical steel reinforcement 4 and the transverse steel reinforcement 5; determine the strength parameters of the concrete 2; determine the sectional geometric dimensions of the steel pipe 1, the size of the steel or steel plate, and the strength parameters of the steel;

[0065] Step 2, the calculation can be carried out according to the following formula:

[0066] N≤Nc

[0067] N c = α [f c ′A c +f a ′A a +f s ′A s + β (f c ′A c )

[0068] In the formula: N is the design value of the axial force of the reinforced steel pipe concrete arch;

[0069] N c is the design value of the axial load carrying capacity of the reinforced steel pipe concrete arch;

[0070] f c—design value of compressive strength of concrete 2;

[0071] f a —design value of compressive strength of steel pipe 1;

[0072] f s —design value of compressive strength of longitudinal steel bar 4;

[0073] A c —cross-sectional area of reinforced steel pipe concrete arch;

[0074] A a —cross-sectional area of steel pipe 1;

[0075] A s —cross-sectional area of longitudinal steel bar 4;

[0076] α —reduction coefficient of arch bearing capacity, determined by considering the interface of steel pipe inner wall, concrete strength, longitudinal steel bar reinforcement ratio and other factors, 0.6-1.0;

[0077] β —confinement effect coefficient of concrete, determined by considering the shape, distribution spacing of transverse steel bar, shape of steel pipe, thickness of steel pipe, strength of concrete and other factors, 0-2.0.

[0078] The strength parameters in the formula are valued according to existing standards or by experiment, and the geometric parameters are valued according to actual size or nominal size. Repeat steps 1-2, and compare the arch axial compression bearing capacity with the maximum axial compression force calculated by the actual working load of the structure. If it is greater than the maximum axial compression force, it is acceptable.

[0079] A construction method of a reinforced steel pipe concrete arch, the construction steps are as follows:

[0080] Step one, pre-process steel pipe 1, outer steel connecting piece 3, inner steel reinforcing piece 7, stud (if any) in the factory, and fix and connect them into one body; according to the needs, make vertical steel bar 4, transverse steel bar 5, steel cage 6 and / or additional steel cage 8;

[0081] Step two, first construct the pre-processed steel pipe 1, and fix it after axial and arc calibration positioning;

[0082] Step three, place the steel cage 4 into the steel pipe, and fix it after axial and arc calibration positioning;

[0083] Step four, then hoist the next section of steel pipe 1 to the side of the already installed steel pipe 1, align it and temporarily fix it, and weld or bolt it into one body with the already installed steel pipe 1;

[0084] Step five, place the steel cage 4 into the steel pipe 1, connect it with the already installed steel cage 4, and fix it after calibration positioning;

[0085] Step six, pouring concrete, curing to the predetermined strength.

[0086] Preferably, the construction method of the reinforced steel pipe concrete arch, in step one, the steel pipe 1 and the reinforcement cage 6 and / or the additional reinforcement cage 8 are fixedly connected in the factory, and other construction steps are adjusted accordingly.

[0087] The above examples only express several embodiments of the patent, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A reinforced steel-concrete composite arch, characterized in that: It includes a steel pipe (1), concrete (2), an outer steel connector (3), a reinforcing cage (4), and a hanger (B); the reinforcing cage (4) includes transverse reinforcing bars (5) and longitudinal reinforcing bars (6), the transverse reinforcing bars (5) being arranged vertically along the longitudinal reinforcing bars (6) at intervals; the reinforcing cage (4) is located inside the steel pipe (1); the outer steel connector (3) is located outside the steel pipe (1) and is arranged corresponding to the hanger (B) to be installed; the outer steel connector (3) is fixedly connected to the steel pipe (1); the concrete (2) fills the steel pipe (1).

2. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The outer steel connector (3) is a steel plate; the steel plate has holes; the holes have pins that connect the rod to the outer steel connector (3).

3. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The steel pipe (1) has an inner steel reinforcing member (7) and / or a stud; the inner steel reinforcing member (7) is fixedly connected to the steel pipe (1); the inner steel reinforcing member (7) is a steel bar ring or a steel plate hoop.

4. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The steel cage (4) is continuous along the steel pipe arch; the transverse steel bars (5) are either spaced more densely or have a larger diameter in the area corresponding to the hanger (B).

5. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The transverse reinforcement (5) is a ring stirrup or a spiral stirrup.

6. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The steel pipe (1) has an additional reinforcing cage (8), which is located inside the reinforcing cage (6).

7. The reinforced steel-concrete composite arch according to claim 1, characterized in that: The steel pipe (1) is provided with longitudinal stiffening ribs, which are fixedly connected to the steel pipe (1) as a whole; the outer steel connector (3) is a ring-shaped steel plate.

8. A method for calculating the axial compressive bearing capacity of a reinforced steel-concrete composite arch, characterized in that, The specific steps are as follows: Step 1: Determine the diameter, number, strength and arrangement of the vertical reinforcing bars (4) and the horizontal reinforcing bars (5); determine the strength parameters of the concrete (2); determine the cross-sectional geometry, steel section or steel plate size and steel strength parameters of the steel pipe (1); Step 2 can be verified using the following formula: N≤N c N c =α[f c ′A c +f a ′A a +f s ′A s +β(f c ′A c )] Where: N——Design value of axial force of reinforced steel-concrete composite arch; N c —Design value of axial bearing capacity of reinforced steel-concrete composite arch; f c —Design value of compressive strength of concrete (2); f′ a —Design value of compressive strength of steel pipe (1); f′ s —Design value of compressive strength of longitudinal reinforcement (4); A c —Cross-sectional area of ​​reinforced steel-concrete composite arch; A a —The cross-sectional area of ​​the steel section or steel plate of the steel pipe (1); A s —Cross-sectional area of ​​longitudinal reinforcement (4); α—Arch bearing capacity reduction coefficient, determined considering factors such as the steel pipe inner wall interface, concrete strength, and longitudinal reinforcement ratio, ranging from 0.6 to 1.0; β—Concrete confinement effect coefficient, determined by considering factors such as the shape and spacing of transverse reinforcement, the shape and thickness of steel pipe, and concrete strength, and is taken as 0 to 2.

0. The strength parameters in the formula are taken according to existing standards or through experiments, and the geometric parameters are taken according to actual or nominal dimensions. Repeat steps 1 to 2, and compare the arch axial bearing capacity with the maximum axial pressure calculated by the structure based on the actual working conditions. If it is greater than the maximum axial pressure, it is acceptable.

9. A construction method for a reinforced steel-concrete composite arch, characterized in that, The construction steps are as follows: Step 1: Pre-process steel pipe (1), outer steel connector (3), inner steel reinforcement (7), and studs (if any) in the factory and fix them together as a whole; make vertical steel bars (4), horizontal steel bars (5), steel cages (6) and / or additional steel cages (8) as needed; Step 2: First, construct the pre-processed steel pipe (1), and fix it after axial and arc alignment and positioning; Step 3: Place the steel cage (4) into the steel pipe, calibrate and position it axially and arcwise, and then fix it. Step 4: Then hoist the next section of steel pipe (1) to the side of the already installed steel pipe (1), align it and temporarily fix it, and weld or bolt it to the already installed steel pipe (1) as one piece; Step 5: Place the steel cage (4) into the steel pipe (1), connect it to the already installed steel cage (4), and fix it after calibration and positioning; Step six: Pour concrete and cure it to the predetermined strength.

10. The construction method of the reinforced steel-concrete composite arch according to claim 1, characterized in that: In step one, the pre-fabricated steel pipe (1) is fixedly connected to the steel cage (6) and / or additional steel cage (8) in the factory, and other construction steps are adjusted accordingly.

Images