High-corrosion-resistance and anti-seismic toughness concrete column with FRP (Fiber Reinforced Plastic) bar-steel bar mixed reinforcement

Abstract

The utility model discloses an FRP (fiber reinforced plastic) bar-steel bar mixed reinforced concrete column with high corrosion resistance and shock resistance toughness, which comprises a concrete layer, an FRP bar framework and a steel bar framework, the FRP bar framework is positioned on one side close to the surface of the concrete layer, the steel bar framework is positioned on the inner side of the FRP bar framework, and the steel bar framework is formed by a plurality of steel longitudinal bars and a plurality of steel stirrups. The FRP bar framework is formed by a plurality of FRP longitudinal bars and a plurality of FRP stirrup belts. According to the concrete column, the corrosion-resistant FRP longitudinal bars and the FRP stirrup belts are arranged on the outer side, the steel bars prone to corrosion are arranged on the inner side, linear elasticity and corrosion resistance of FRP materials and the excellent energy dissipation capacity of the steel bars are fully utilized, and the concrete column with the FRP bars and the steel bars in mixed reinforcement and good in corrosion resistance and seismic toughness is formed; and moreover, the used FRP ribs can provide stable secondary rigidity after the steel bars are yielded, so that residual deformation of the column after unloading is reduced, and rapid repair of the concrete column after an earthquake is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of civil engineering structural components, in particular to a high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement. Background Art

[0002] Reinforced concrete columns serving in a corrosive environment will face serious steel corrosion problems, which will destroy the bond between steel and concrete and shorten the service life of the structure. In addition, under the action of earthquakes, reinforced concrete columns may have problems such as steel yielding, resulting in large residual deformation after the earthquake, steel stirrup yielding, causing steel longitudinal reinforcement buckling, leading to structural collapse and insufficient ductility, making the structure difficult to repair or having to be demolished.

[0003] Fiber reinforced polymer (FRP) bars are corrosion-resistant, high-strength, and linearly elastic, making them ideal alternatives to steel bars. Although FRP reinforced concrete columns do not have the corrosion problem caused by reinforcement rust expansion, and have small residual deformation under earthquakes, the linear elasticity of FRP bars makes the energy dissipation capacity and ductility of concrete columns under earthquakes far less than those of reinforced concrete columns, and the use of all FRP bars will increase economic costs.

[0004] Therefore, it is worth studying how to use FRP bars at low cost to solve the problems of easy corrosion of reinforced concrete columns, poor seismic toughness, and insufficient ductility and energy dissipation capacity of FRP reinforced concrete columns. Utility Model Content

[0005] The purpose of the utility model is to provide a highly corrosion-resistant and seismic-resistant concrete column with FRP bar-steel mixed reinforcement, which fully utilizes the linear elasticity and high strength of FRP materials and the energy dissipation capacity of steel bars. By surface treating the FRP bars, the bonding strength and ductility between the FRP bars and concrete can be improved. The bonding between the FRP bars treated with cross-wound ribs and the concrete shows a good post-peak bonding strength, which is beneficial to improving the ductility of the structure; the strength of the FRP stirrup belt produced by continuous fiber integrated winding can reach 95% of the straight bars, which can provide continuous constraints on the concrete and avoid the phenomenon of steel longitudinal reinforcement buckling caused by the yielding of steel stirrups, thereby providing the structure with anti-collapse ability. The use of two FRP bars and steel bars with different mechanical properties mixed in concrete and the full use of the characteristics of the two materials can solve the problems of corrosion and poor seismic toughness of existing reinforced concrete structures.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A highly corrosion-resistant and seismic-tough concrete column with FRP tendon-steel mixed reinforcement comprises a concrete layer, an FRP tendon skeleton and a steel skeleton, wherein the FRP tendon skeleton is located on a side close to the surface of the concrete layer, the steel skeleton is located on the inner side of the FRP tendon skeleton, the steel skeleton is formed by a plurality of steel longitudinal bars and a plurality of steel stirrups, and the FRP tendon skeleton is formed by a plurality of FRP longitudinal bars and a plurality of FRP stirrup strips.

[0008] Furthermore, the net distance between the FRP reinforcement frame and the steel reinforcement frame is 25 mm to 50 mm.

[0009] Furthermore, the protective distance between the FRP reinforcement frame and the surface of the concrete layer is ≥15 mm.

[0010] Furthermore, the surface of the FRP longitudinal bar has bidirectional cross-wound ribs, and the spacing between the bidirectional cross-wound ribs is 10 mm.

[0011] Furthermore, the FRP stirrups are made by continuous fiber winding and integrated molding, and the tensile strength of the bending zone is 95% of the tensile strength of the straight reinforcement.

[0012] Furthermore, the cross-sectional width of the FRP stirrup strip is 20 mm and the thickness is 6 mm.

[0013] Furthermore, the FRP longitudinal bars and the FRP stirrups as well as the steel longitudinal bars and the steel stirrups are connected by tying with cable ties.

[0014] Furthermore, the net spacing between the FRP longitudinal bars and between the steel longitudinal bars is 25 mm to 200 mm.

[0015] Furthermore, the net spacing between the FRP stirrups and between the steel stirrups is 25 mm to 200 mm.

[0016] Furthermore, the diameters of the FRP longitudinal bars and the steel longitudinal bars are both 10 mm to 25 mm.

[0017] Furthermore, the diameter of the steel stirrup is 6 mm to 12 mm.

[0018] Furthermore, the FRP longitudinal bars, FRP stirrup strips, steel longitudinal bars and steel stirrups are arranged over the entire length of the concrete column in the longitudinal direction.

[0019] Furthermore, the number of FRP stirrups provided in the plastic hinge region at the bottom of the concrete column is greater than the number of FRP stirrups provided at the upper portion of the concrete column.

[0020] Furthermore, the concrete used for pouring the concrete layer is ordinary concrete.

[0021] Furthermore, the longitudinal steel bars are ordinary hot-rolled ribbed steel bars.

[0022] Furthermore, the FRP material used for the FRP longitudinal bars and FRP stirrups is made of fiber and resin, wherein the fiber can be any one of carbon fiber, glass fiber, basalt fiber, and aramid fiber, and the resin can be any one of epoxy resin, vinyl resin, and unsaturated resin.

[0023] Compared with the prior art, the utility model provides a high corrosion resistance and seismic toughness concrete column with FRP bar-steel mixed reinforcement, which has the following beneficial effects:

[0024] (1) The utility model arranges corrosion-resistant FRP longitudinal bars and FRP stirrups on the outside and corrosion-prone steel bars on the inside, making full use of the linear elasticity and corrosion resistance of the FRP material and the excellent energy absorption capacity of the steel bars to form a concrete column with mixed reinforcement of FRP bars and steel bars with good corrosion resistance and seismic toughness; and the FRP bars used can provide stable secondary stiffness after the steel bars yield, satisfying a secondary stiffness ratio of more than 5%, so as to reduce the residual deformation of the column after unloading, which is conducive to the rapid repair of the concrete column after the earthquake.

[0025] (2) The surface of the FRP longitudinal reinforcement is treated with cross-wrapped ribs, which can improve the bonding ductility between the FRP reinforcement and the concrete. In the large deformation stage of the concrete column, the FRP reinforcement and the concrete can achieve stable sliding to improve the ductility of the concrete column.

[0026] (3) FRP stirrups are produced by continuous fiber winding and integrated molding. They have high tensile strength and strong deformation capacity. Under the action of earthquakes, they can continuously restrain the concrete at the column base, prevent the peeling of the concrete protective layer, improve the ductility of the column, prevent the buckling of the longitudinal reinforcement, and avoid the collapse of the concrete column.

[0027] (4) The utility model retains the steel bars and their excellent ductility and energy dissipation capacity under earthquake action, and delays the corrosion of the steel bars by increasing the protective distance between the FRP reinforcement skeleton and the surface of the concrete layer, thereby ensuring the durability of the concrete column. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 It is a schematic diagram of the structure of the utility model;

[0030] Figure 2A schematic diagram of reinforcement arrangement along the cross section of a concrete column in Example 1;

[0031] Figure 3 Schematic diagram of reinforcement arrangement along the cross section of a concrete column in Example 2.

[0032] Figure numerals: 1. concrete layer; 2. steel longitudinal reinforcement; 3. FRP longitudinal reinforcement; 4. FRP stirrups; 5. steel stirrups. DETAILED DESCRIPTION

[0033] The technical solution of the utility model will be clearly and completely described below through detailed embodiments and in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] Example 1

[0035] This embodiment provides a high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement, such as Figure 1 and Figure 2 As shown, it specifically includes a concrete layer 1, an FRP reinforcement skeleton and a steel reinforcement skeleton. The FRP reinforcement skeleton is located on the side close to the surface of the concrete layer 1, and the steel reinforcement skeleton is located on the inner side of the FRP reinforcement skeleton. The steel reinforcement skeleton is formed by a plurality of steel longitudinal bars 2 and a plurality of steel stirrups 5, and the FRP reinforcement skeleton is formed by a plurality of FRP longitudinal bars 3 and a plurality of FRP stirrups 4. The FRP longitudinal bars 3, the FRP stirrups 4, the steel longitudinal bars 2 and the steel stirrups 5 are all arranged in the entire length range of the longitudinal direction of the concrete column. The FRP longitudinal bars 3 and the FRP stirrups 4, as well as the steel longitudinal bars 2 and the steel stirrups 5, are connected by tying with a tie.

[0036] In this embodiment, the cross section of the concrete column is circular, and the shapes of the FRP stirrups 4 and the steel stirrups 5 are circular.

[0037] In some specific embodiments, the concrete poured in the concrete layer 1 is ordinary concrete. The steel longitudinal reinforcement 2 is ordinary hot-rolled ribbed steel bars. The FRP material used for the FRP longitudinal reinforcement 3 and the FRP stirrups 4 is made of fiber and resin, wherein the fiber can be any one of carbon fiber, glass fiber, basalt fiber, and aramid fiber, and the resin can be any one of epoxy resin, vinyl resin, and unsaturated resin.

[0038] In some specific embodiments, the net spacing between the FRP reinforcement skeleton and the steel reinforcement skeleton is 25 mm to 50 mm. The protective distance between the FRP reinforcement skeleton and the surface of the concrete layer is ≥ 15 mm. The net spacing between the FRP longitudinal bars and between the steel longitudinal bars is 25 mm to 200 mm. The diameters of the FRP longitudinal bars and the steel longitudinal bars are both 10 mm to 25 mm. The diameter of the steel stirrups is 6 mm to 12 mm.

[0039] The FRP longitudinal reinforcement in concrete can provide secondary stiffness after the steel bar yields. To achieve stable secondary stiffness, the amount of FRP longitudinal reinforcement is adjusted so that the secondary stiffness is greater than r c (As shown below) is greater than 5%.

[0040]

[0041] Where: r c is the secondary stiffness ratio, K1 is the stiffness before yielding, K2 is the stiffness after yielding, V y is the yield level load, δ y is the yield displacement, δ is the displacement of any point after yielding, V δ is the horizontal load corresponding to the displacement δ.

[0042] In some specific embodiments, the surface of the FRP longitudinal reinforcement 3 has bidirectional cross-wound ribs, and the spacing between the bidirectional cross-wound ribs is 10 mm.

[0043] In some specific embodiments, the FRP stirrup belt 4 is a stirrup belt made by continuous fiber winding and integrated molding. The tensile strength of the bending zone is 95% of the tensile strength of the straight reinforcement. The cross-sectional width of the FRP stirrup belt is 20 mm and the thickness is 6 mm.

[0044] In some specific implementations, the net spacing between the FRP stirrups 4 and between the steel stirrups 5 is 25 mm to 200 mm.

[0045] Preferably, Figure 1 As shown in the figure, the number of FRP stirrups provided in the plastic hinge area at the bottom of the concrete column is greater than the number of FRP stirrups provided in the upper part of the concrete column. Specifically, the amount of FRP stirrups can be increased in the plastic hinge area at the bottom of the concrete column, and the height of the plastic hinge area at the bottom of the column can be determined by the following formula:

[0046]

[0047] Where: φ y is the yield curvature, φ u is the limit state curvature, L is the total height of the column, δ u is the ultimate displacement of the column top.

[0048] In addition, to ensure that the FRP stirrups can provide sufficient concrete confinement, the cross-sectional area of ​​the FRP stirrups in the plastic hinge area at the column base should not be less than the calculated value of the following formula:

[0049]

[0050] Where: A sh is the cross-sectional area of ​​the FRP stirrups, s is the stirrup spacing, h c is the maximum distance between the tension and compression longitudinal reinforcement, f co is the compressive strength of confined concrete, f Fh is the tensile strength of FRP stirrups, A g is the gross cross-sectional area of ​​the concrete column, A g is the net cross-sectional area of ​​concrete, P / P0 is the vertical load level, δ is the design displacement angle, k e is the constraint coefficient.

[0051] Example 2

[0052] This embodiment provides another high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement, such as Figure 1 and Figure 3 As shown, the reinforcement arrangement is the same as that of Example 1. The difference from Example 1 is that the cross section of the concrete column is square, and accordingly, the shapes of the FRP stirrups and steel stirrups used are also square.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0054] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high corrosion resistance and seismic toughness concrete column with FRP tendon-steel mixed reinforcement, comprising a concrete layer, an FRP tendon skeleton and a steel skeleton, characterized in that: The FRP reinforcement skeleton is located on a side close to the surface of the concrete layer, the steel reinforcement skeleton is located on the inner side of the FRP reinforcement skeleton, the steel reinforcement skeleton is formed by a plurality of steel longitudinal bars and a plurality of steel stirrups, and the FRP reinforcement skeleton is formed by a plurality of FRP longitudinal bars and a plurality of FRP stirrups.

2. The high corrosion resistance and seismic toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1 is characterized in that: The net distance between the FRP reinforcement frame and the steel reinforcement frame is 25 mm to 50 mm; the protection distance between the FRP reinforcement frame and the surface of the concrete layer is ≥15 mm.

3. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1 is characterized in that: The surface of the FRP longitudinal reinforcement is provided with bidirectional cross-wound ribs, and the spacing between the bidirectional cross-wound ribs is 10 mm.

4. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1 is characterized in that: The FRP stirrup belt is a stirrup belt made by continuous fiber winding and integrated molding.

5. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 4 is characterized in that: The cross-sectional width of the FRP stirrups is 20 mm and the thickness is 6 mm.

6. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1 is characterized in that: The FRP longitudinal bars and FRP stirrups as well as the steel longitudinal bars and steel stirrups are connected by cable ties.

7. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1 is characterized in that: The net spacing between FRP longitudinal bars and steel longitudinal bars is 25mm~200mm; the net spacing between FRP stirrups and steel stirrups is 25mm~200mm.

8. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1, characterized in that: The diameters of the FRP longitudinal bars and the steel longitudinal bars are both 10 mm to 25 mm; the diameter of the steel stirrups is 6 mm to 12 mm.

9. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 1, characterized in that: FRP longitudinal bars, FRP stirrups, steel longitudinal bars and steel stirrups are arranged throughout the entire longitudinal length of the concrete column.

10. The high corrosion resistance and earthquake toughness concrete column with FRP bar-steel mixed reinforcement according to claim 9, characterized in that: The number of FRP stirrups arranged in the plastic hinge area at the bottom of the concrete column is greater than the number of FRP stirrups arranged at the upper part of the concrete column.

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