Methods, apparatus and equipment for determining the flexural bearing capacity of rebar lap splices

Abstract

This invention provides a method, apparatus, and equipment for determining the flexural bearing capacity of a rebar lap splice. The method includes: obtaining the tensile force and bending moment arm of the main tension lap splice rebar at the most unfavorable section of a diaphragm wall; and determining the flexural bearing capacity of the main tension lap splice rebar at the most unfavorable section of the diaphragm wall based on the tensile force and bending moment arm of the main tension lap splice rebar. This invention achieves accurate determination of the flexural capacity at the rebar lap splice.

Description

Technical Field

[0001] This invention relates to the field of engineering technology, and in particular to a method, apparatus and equipment for determining the flexural bearing capacity of steel bar lap joints. Background Technology

[0002] With the maturity and advancement of construction technology, diaphragm walls are increasingly used in the foundations of large bridges due to their advantages such as short construction period, reliable quality, high rigidity, low noise, and applicability to various foundation conditions. They are also showing a strong trend of replacing caisson foundations and pile foundations in ultra-deep and ultra-large foundation support structures.

[0003] Reinforcing bar lap joints are a type of rigid joint formed by non-contact interlocking of multiple rows of reinforcing mesh extending outwards from the first-stage and second-stage trench sections. They can effectively transmit tensile force, shear force, and bending moment, and have good overall integrity. However, the calculation of the bending bearing capacity of rigid joints in diaphragm walls in China is still in its early stages.

[0004] In related technologies, the flexural bearing capacity of lap splices in diaphragm walls is determined based on the anchorage force of concrete to the reinforcing bars. This method is suitable for lap splices with a lap spacing of less than 5 times the diameter of the reinforcing bars, requiring sufficient anchorage and involving complex calculations. However, in the foundations of large bridge diaphragm walls, the lap spacing is generally larger (≥ 5 times the diameter of the reinforcing bar), resulting in less sufficient anchorage. In this case, the anchorage force of concrete to the reinforcing bars is not the primary factor. Therefore, accurately determining the flexural bearing capacity of lap splices with larger lap spacing is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the problems in the prior art, embodiments of the present invention provide a method, apparatus, and equipment for determining the flexural bearing capacity of rebar lap joints.

[0006] Specifically, the embodiments of the present invention provide the following technical solutions:

[0007] In a first aspect, embodiments of the present invention provide a method for determining the flexural bearing capacity of a rebar lap splice, comprising:

[0008] Obtain the tensile force and bending moment arm of the main tension lap splice reinforcement at the most unfavorable section of the diaphragm wall;

[0009] Based on the tensile force and bending moment arm of the main tension lapped reinforcement, determine the bending bearing capacity of the main tension lapped reinforcement joint at the most unfavorable section of the diaphragm wall.

[0010] Furthermore, obtaining the tensile force and bending moment arm of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall includes:

[0011] Obtain the punching shear failure strength of lapped steel bars and the stress transfer reduction factor between lapped steel bars and concrete;

[0012] Based on the punching shear failure strength of the lapped steel bars and the stress transfer reduction coefficient between the lapped steel bars and the concrete, the tensile force of the main tension lapped steel bars on the most unfavorable section of the continuous wall is determined.

[0013] Further, obtaining the punching shear failure strength of the lapped reinforcing bars includes:

[0014] Obtain concrete shear stress, non-contact lap length of lapped reinforcing bars, lap width of lapped reinforcing bars, and concrete tensile-shear reduction factor;

[0015] The punching shear failure strength of the lapped reinforcing bars is determined based on the concrete shear stress, the non-contact lap length of the lapped reinforcing bars, the lap width of the lapped reinforcing bars, and the concrete tensile-shear reduction coefficient.

[0016] Further, obtaining the bending arm of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall includes:

[0017] Obtain the height of the concrete flexural section, the thickness of the protective layer for the main tensile reinforcement, and the height of the concrete compression zone.

[0018] Based on the height of the concrete bending section, the thickness of the protective layer of the main tensile reinforcement, and the height of the compression zone of the concrete section, the bending arm of the main tensile lapped reinforcement on the most unfavorable section of the continuous wall is determined.

[0019] Further, determining the flexural bearing capacity of the lap splice of the main tensile reinforcement at the most unfavorable section of the diaphragm wall based on the tensile force and flexural lever arm of the main tensile lap splice includes:

[0020] The flexural capacity of the lap splices of the main tensile reinforcement at the most unfavorable section of a diaphragm wall can be determined using the following formula:

[0021] M d =β1·α1·τ·l0·b·Z

[0022] Among them, M d The flexural bearing capacity of the lap splice of the main tension reinforcement at the most unfavorable section of the diaphragm wall is represented by β1·α1·τ·l0·b; the tensile force of the lap splice of the main tension reinforcement of the diaphragm wall is represented by α1·τ·l0·b; the punching shear failure strength of the lap splice is represented by α1; the stress transfer reduction factor between the lap splice and the concrete is represented by α1; the tensile-shear reduction factor of the concrete is represented by τ; the shear stress of the concrete is represented by l0; the non-contact lap length of the lap splice is represented by l0; the width of the lap splice is represented by b; and the flexural arm of the lap splice of the main tension reinforcement of the diaphragm wall is represented by Z.

[0023] Furthermore, the stress of the main tensile lapped reinforcement bars of the diaphragm wall is obtained;

[0024] Based on the stress transfer reduction factor, the punching shear failure strength of the lapped reinforcement, and the stress of the main tensile lapped reinforcement of the continuous wall, determine the minimum reinforcement cross-sectional area of ​​the lapped reinforcement of the continuous wall.

[0025] Furthermore, based on the flexural bearing capacity of the lap joint of the main tension reinforcement on the most unfavorable section of the diaphragm wall and the first tensile force and the first flexural lever arm, the flexural bearing capacity of the lap joint of the main tension and auxiliary tension reinforcement on the most unfavorable section of the diaphragm wall is determined; the first tensile force represents the tensile force corresponding to the auxiliary tension lap joint reinforcement; the first flexural lever arm represents the flexural lever arm corresponding to the auxiliary tension lap joint reinforcement.

[0026] Secondly, embodiments of the present invention also provide a device for determining the flexural bearing capacity of a rebar lap joint, comprising:

[0027] The acquisition module is used to acquire the tensile force and bending moment arm of the main tension lap splice reinforcement at the most unfavorable section of the continuous wall;

[0028] The determination module is used to determine the flexural bearing capacity of the lap joint of the main tension reinforcement on the most unfavorable section of the continuous wall based on the tensile force and bending moment arm of the main tension lap reinforcement.

[0029] Thirdly, embodiments of the present invention also provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for determining the flexural bearing capacity of the rebar lap joint as described in the first aspect.

[0030] Fourthly, embodiments of the present invention also provide a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for determining the flexural bearing capacity of the rebar lap joint as described in the first aspect.

[0031] Fifthly, embodiments of the present invention also provide a computer program product, including a computer program that, when executed by a processor, implements the method for determining the flexural bearing capacity of steel bar lap joints as described in the first aspect.

[0032] The method, apparatus, and equipment for determining the flexural bearing capacity of steel reinforcement lap joints provided in this invention embodiment are based on the situation in the foundation of underground continuous wall of large bridges where the lap spacing is large. When the main tensile steel reinforcement of the steel reinforcement lap joint has not fully yielded under the ultimate bending moment and the concrete in the compression zone has not collapsed, the plain concrete position at the end of the lap steel reinforcement is taken as the most unfavorable section. In addition to the main compressive and main tensile lap steel reinforcement, there are no other lap steel reinforcements on the most unfavorable section of the large-spacing non-contact lap joint of the continuous wall. Therefore, based on the tensile force and bending moment arm of the main tensile lap steel reinforcement on the most unfavorable section of the continuous wall, the flexural bearing capacity of the steel reinforcement lap joint of the continuous wall can be accurately and quickly determined, realizing the accurate determination of the flexural capacity of the steel reinforcement lap joint of the underground continuous wall when the lap steel reinforcement spacing is large. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a flowchart illustrating the method for determining the flexural bearing capacity of a rebar lap joint provided in an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of a rebar lap joint provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the weak surface of punching shear failure between lapped steel bars provided in an embodiment of the present invention;

[0037] Figure 4 This is a simplified schematic diagram of the punching shear strength between lapped reinforcing bars provided in an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the device for determining the bending bearing capacity of a rebar lap joint provided in an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this 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 this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] The method of this invention can be applied to engineering scenarios to accurately determine the bending bearing capacity of steel bar lap joints.

[0042] In related technologies, the flexural bearing capacity of diaphragm wall joints is determined based on the anchorage force of concrete to the reinforcing bars. This method is suitable for lapped reinforcing bars with a lap spacing of less than 5 times the diameter of the reinforcing bars, requiring sufficient anchorage and involving complex calculations. However, in the foundations of large bridge diaphragm walls, the lap spacing is generally larger (≥ 5 times the diameter of the reinforcing bar), and the anchorage of the lapped reinforcing bars is not particularly sufficient. In this case, the anchorage force of concrete to the reinforcing bars is not the primary factor. Therefore, accurately determining the flexural bearing capacity of reinforcing bar lap joints when the lap spacing is large is a problem that urgently needs to be solved by those skilled in the art.

[0043] The method for determining the flexural bearing capacity of steel reinforcement lap splices in this invention is based on the case of large lap spacing in the foundation of underground continuous walls of large bridges. When the main tensile steel reinforcement has not fully yielded under the ultimate bending moment of the lap splice and the concrete in the compression zone has not collapsed, the plain concrete position at the end of the lap steel reinforcement is taken as the most unfavorable section. In addition to the main compressive and main tensile lap steel reinforcement, there are no other lap steel reinforcements on the most unfavorable section of the large-spacing non-contact lap joint of the continuous wall. Therefore, based on the tensile force and bending moment arm of the main tensile lap steel reinforcement on the most unfavorable section of the continuous wall, the flexural bearing capacity of the steel reinforcement lap splices of the continuous wall can be accurately and quickly determined, realizing the accurate determination of the flexural capacity of the steel reinforcement lap splices of underground continuous walls under the condition of large lap steel reinforcement spacing.

[0044] The following is combined with Figures 1-6 The technical solution of the present invention will be described in detail with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0045] Figure 1 This is a flowchart illustrating an embodiment of the method for determining the flexural bearing capacity of a rebar lap joint provided by the present invention. Figure 1 As shown, the method provided in this embodiment includes:

[0046] Step 101: Obtain the tensile force and bending moment arm of the main tension lap splice reinforcement at the most unfavorable section of the continuous wall;

[0047] Specifically, for ultra-deep and ultra-large foundations, the excavation depth required for diaphragm walls is very large, generally requiring phased excavation. Joints are needed between different phases to achieve coordinated stress distribution. The joint connection structure between unit sections is a key core component of the diaphragm wall system and a core technology in diaphragm wall construction. In recent years, various joint types have been developed to improve the stress performance of diaphragm wall unit joints, which can be broadly classified into flexible joints and rigid joints. Flexible joints can generally only withstand pressure, not tension, shear, or bending moments. Therefore, flexible joints have poor stiffness, integrity, and shear resistance, and are prone to deformation under stress. Rigid joints, on the other hand, can generally withstand tension, shear, and lateral bending moments, exhibiting better overall integrity.

[0048] Non-contact lap joints for diaphragm walls are a type of rigid joint formed by non-contact interlocking of multiple rows of reinforcing mesh extending from the first-stage and second-stage trench sections. The bonding between the reinforcing bars and concrete in the joint connects the first-stage and second-stage trench wall sections into a unified whole. This type of joint effectively transfers tensile, shear, and lateral bending moments, exhibiting good overall integrity. It has already been applied in the support structures of some large bridges with ultra-deep and ultra-large foundations, showing promising application prospects. Although there are various types of rigid diaphragm wall joints, research on rigid joints that can reliably transfer loads is limited. Furthermore, a mature method for calculating the actual load-bearing capacity of non-contact lap joints for reinforcing bars has not yet been developed, hindering the further promotion and application of this technology.

[0049] In related technologies, the flexural bearing capacity of diaphragm wall joints is determined based on the anchorage force of concrete to the reinforcing bars. This method is suitable for lapped reinforcing bars with a lap spacing of less than 5 times the diameter of the reinforcing bars, requiring sufficient anchorage and involving complex calculations. However, in the foundations of large bridge diaphragm walls, the lap spacing is generally larger (≥ 5 times the diameter of the reinforcing bar), and the anchorage of the lapped reinforcing bars is not particularly sufficient. In this case, the anchorage force of concrete to the reinforcing bars is not the primary factor. Therefore, accurately determining the flexural bearing capacity of reinforcing bar lap joints when the lap spacing is large is a problem that urgently needs to be solved by those skilled in the art.

[0050] Optionally, such as Figure 2As shown, to solve the above problems, this embodiment of the invention is based on the case where the lap spacing in the foundation of a large bridge diaphragm wall is generally large (lap spacing ≥ N times the diameter of the reinforcing bar; optionally, N is 5). The most unfavorable section is the plain concrete position at the end of the outermost lapped reinforcing bar. When the main tensile reinforcing bar has not fully yielded under the ultimate bending moment of the lap joint, and the concrete in the compression zone has not collapsed, there are no other lapped reinforcing bars besides the main compressive and main tensile lapped reinforcing bars on the most unfavorable section of the large-spacing non-contact lapped diaphragm wall joint. Its flexural bearing capacity Md can be determined by multiplying the total tensile force Fs of the lapped reinforcing bars on the main tensile side by the lever arm Z. Optionally, if there is only one tensile lapped reinforcing bar in the diaphragm wall, then this tensile lapped reinforcing bar is also the main tensile reinforcing bar of the diaphragm wall. Therefore, the method of this embodiment of the invention is applicable to determining the flexural bearing capacity of the lapped joint of the reinforcing bar in a diaphragm wall when there is only one tensile lapped reinforcing bar, that is, when there is only the main tensile reinforcing bar and no auxiliary tensile reinforcing bars.

[0051] Therefore, in order to accurately determine the flexural bearing capacity of the steel reinforcement lap joints of the continuous wall, in this embodiment of the invention, the tensile force and flexural lever arm of the main tension lap joint steel reinforcement on the most unfavorable section of the continuous wall are first obtained.

[0052] Step 102: Determine the bending bearing capacity of the lap splice of the main tension reinforcement on the most unfavorable section of the continuous wall based on the tensile force and bending moment arm of the main tension lap splice.

[0053] Specifically, after obtaining the tensile force and bending moment arm of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall, since there are no other lapped reinforcements besides the main compression and tension lapped reinforcements at the most unfavorable section of the large-spacing non-contact lapped joint of the diaphragm wall, the bending capacity of the diaphragm wall reinforcement lapped joint can be determined based on the obtained tensile force and bending moment arm of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall. Optionally, the tensile force of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall can be multiplied by the bending moment arm to obtain the bending capacity of the diaphragm wall reinforcement lapped joint. Optionally, the bending capacity of the diaphragm wall reinforcement lapped joint can be determined using the following formula:

[0054] M d =F s ×Z

[0055] Among them, M d F represents the flexural bearing capacity of the lap splice of steel reinforcement in a diaphragm wall. s Z represents the tensile force of the lapped steel bar under tension; Z represents the bending moment arm.

[0056] The method described in the above embodiment is based on the case where the lap spacing in the foundation of a large bridge diaphragm wall is large. When the main tensile reinforcement of the lap splice has not fully yielded under the ultimate bending moment and the concrete in the compression zone has not collapsed, the plain concrete position at the end of the lap reinforcement is taken as the most unfavorable section. In addition to the main compressive and main tensile lap reinforcement, there are no other lap reinforcements on the most unfavorable section of the diaphragm wall joint with large spacing of reinforcement. Therefore, based on the tensile force and bending moment arm of the main tensile lap reinforcement on the most unfavorable section of the diaphragm wall, the bending bearing capacity of the reinforcement lap splice of the diaphragm wall can be accurately and quickly determined, realizing the accurate determination of the bending capacity of the reinforcement lap splice of the diaphragm wall under the case of large lap reinforcement spacing.

[0057] In one embodiment, obtaining the tensile force and bending moment arm of the main tension lap splice reinforcement at the most unfavorable section of the diaphragm wall includes:

[0058] Obtain the punching shear failure strength of lapped steel bars and the stress transfer reduction factor between lapped steel bars and concrete;

[0059] Based on the punching shear failure strength of the lapped reinforcement and the stress transfer reduction coefficient between the lapped reinforcement and the concrete, the tensile force of the main tension lapped reinforcement on the most unfavorable section of the continuous wall is determined.

[0060] Specifically, in this embodiment of the invention, based on the case of a large lap spacing in the foundation of a large underground continuous wall for a bridge, the plain concrete position at the end of the lapped reinforcing bar is taken as the most unfavorable section. Furthermore, on the most unfavorable section of the non-contact lapped joint of the reinforcing bar with a large spacing, there are no other lapped reinforcing bars besides the main compression and main tension lapped reinforcing bars. Therefore, based on the tensile force and bending moment arm of the main tension lapped reinforcing bars on the most unfavorable section of the continuous wall, the bending bearing capacity of the reinforcing bar lap joint of the continuous wall can be accurately and quickly determined. Optionally, the tensile force of the main tension lapped reinforcing bar can be determined using the punching shear failure strength of the lapped reinforcing bar; for example, such as... Figure 3 As shown, the weak surface of the rebar lap splice is the punching shear failure surface of the concrete between the lapped rebars. Therefore, the total tensile force of the main lapped rebars on the tension side depends on the tensile and shear strength of the concrete around the punching shear failure surface of the lapped rebars; optionally, as... Figure 4 As shown, when a lap splice of reinforcing bars fails under bending, the failure cracks develop from the outermost tensioned side into the gap between the lapped reinforcing bars. Therefore, the tensile and shear strength of the single-sided punching shear failure surface should be used in the bending calculation. The tensile and shear stress of concrete changes with the punching angle, and the bending resistance arm is also different at different positions along the punching shear failure surface. It is difficult and complicated to calculate using the tensile and shear stress of concrete. Therefore, in this embodiment of the invention, the single-sided concrete shear strength within the lap length range is used to replace the calculation of the tensile force of the lapped reinforcing bars in the continuous wall.

[0061] Alternatively, the tensile force of the main tension lap splice can be determined using the following formula:

[0062] F s =β1×F 冲切

[0063] Among them, F s Indicates the tensile force of the lapped steel reinforcement under tension; F 冲切 β1 represents the punching shear failure strength of the main tensile lapped steel bars; β1 is the stress transfer reduction coefficient between the lapped steel bars and the concrete, which is related to the spacing of the lapped steel bars. When the spacing of the lapped steel bars is small, that is, when the arrangement is relatively dense, β1=1, which means that the punching shear failure strength of the lapped steel bars and the tensile force of the tensile lapped steel bars can achieve a 1:1 equivalent transfer.

[0064] In the case of large bridge underground continuous wall foundations, where the lap spacing is generally large (lap spacing ≥ 5 times the diameter of the steel bar), the anchorage of the lapped steel bars is not particularly sufficient. The weak surface of the steel bar lap joint is the punching shear failure surface between adjacent lapped steel bars. This situation is not controlled by the anchorage force of the concrete to the steel bars, but by the tensile shear strength of the plain concrete on the punching shear failure surface. Therefore, in the embodiments of the present invention, the bending bearing capacity of the underground continuous wall steel bar lap joint can be accurately determined based on the concrete punching shear strength.

[0065] Optionally, when the lap spacing of the rebar lap joint is greater than 5 times the diameter of the lapped rebar, the concrete punching shear failure surface of the lapped rebar gap on the main tension side is taken as the weak surface of the rebar lap joint. The most unfavorable section at the rebar lap joint is selected as the calculation and analysis model. The shear strength of the concrete on one side within the lap length range considering the reduction factor is used to replace the tensile shear strength of the concrete on the punching shear failure surface for simplification. The total tensile force of the tensioned lapped rebar is quickly and accurately determined, and the design flexural bearing capacity of the rebar lap joint is finally obtained by combining the bending moment arm.

[0066] The method described in the above embodiment uses the punching shear failure strength of the lapped steel bars to replace the tensile shear strength of the concrete around the punching shear failure surface of the lapped steel bars, which can quickly and effectively determine the tensile force of the main tensile lapped steel bars. Furthermore, based on the tensile force of the main tensile lapped steel bars, the bending bearing capacity of the steel bar lap joint of the continuous wall can also be determined, thus improving the calculation efficiency of the tensile force of the main tensile lapped steel bars and the bending bearing capacity of the steel bar lap joint of the continuous wall.

[0067] In one embodiment, obtaining the punching shear failure strength of the lapped reinforcing bars includes:

[0068] Obtain concrete shear stress, non-contact lap length of lapped reinforcing bars, lap width of lapped reinforcing bars, and concrete tensile-shear reduction factor;

[0069] The punching shear failure strength of the lapped steel bars is determined based on the concrete shear stress, the non-contact lap length of the lapped steel bars, the lap width of the lapped steel bars, and the concrete tensile-shear reduction coefficient.

[0070] Specifically, the punching shear failure strength of lapped reinforcing bars can be determined using the following formula:

[0071] F 冲切 =α1·τ·l0·b

[0072] Among them, F 冲切 α1 represents the punching shear failure strength of the main tension lap splice; α1 represents the tension-shear reduction coefficient, which is related to the ratio of the non-contact lap length to the non-contact lap spacing, l0 / a, and can be determined by experiments; optionally, when l0 / a>3.5, α1 can be taken as 0.95, when l0 / a=0, α1 is 0, and when α1 is between 0 and 3.5, it can be determined by linear interpolation; τ is the concrete shear stress, which can be determined by experiments; optionally, it can be determined using the following formula: Among them, f cu ...

[0073] The method described above determines the punching shear failure strength of the lapped steel bars by taking the concrete shear stress, the non-contact lap length of the lapped steel bars, the lapped steel bar width, and the concrete tensile-shear reduction coefficient. Based on the determined punching shear failure strength of the lapped steel bars, the tensile force of the main tensile lapped steel bars and the bending bearing capacity of the steel bar lap joint can be accurately determined, thereby achieving accurate determination of the bending capacity of the lapped joint of the underground continuous wall steel bars when the spacing of the lapped steel bars is large.

[0074] In one embodiment, obtaining the bending arm of the main tension lapped reinforcement at the most unfavorable section of the diaphragm wall includes:

[0075] Obtain the height of the concrete flexural section, the thickness of the protective layer for the main tensile reinforcement, and the height of the concrete compression zone.

[0076] The bending arm of the main tensile lapped reinforcement on the most unfavorable section of the diaphragm wall is determined based on the height of the concrete bending section, the thickness of the protective layer of the main tensile reinforcement, and the height of the compression zone of the concrete section.

[0077] Specifically, the bending moment arm Z (the bending moment arm of the main section under the ultimate bending moment of the lap splice) is the distance from the main tension reinforcement to the center point of the resultant force on the compression side:

[0078] Z = ha s -x / 2

[0079] Where h is the height of the bending section, a sThe thickness of the concrete cover for the main tensile reinforcement is given by Z, and x is the height of the compression zone of the section. This height can be measured using concrete strain gauges arranged in an experimental setup, combined with the plane section assumption. Alternatively, when no experimental values ​​are available but the lapped reinforcement on the tensile and compression sides is symmetrically reinforced, the spacing between the main compression and compression lapped reinforcements can be used as the arm of the main bending resistance of the cross section for calculation, i.e., Z = ha. s -a' s ,a' s The thickness of the protective layer for the main compression reinforcement.

[0080] The method described above determines the bending arm of the tensile lapped reinforcement in the diaphragm wall by measuring the height of the concrete bending section, the thickness of the protective layer of the tensile reinforcement, and the height of the compression zone of the concrete section. Based on the determined bending arm, the bending capacity of the lapped joint can be accurately determined, thereby enabling accurate determination of the bending capacity at the lapped joint of the diaphragm wall when the spacing of the lapped reinforcement is large.

[0081] In one embodiment, the flexural bearing capacity of the lap splice of the main tension reinforcement at the most unfavorable section of the diaphragm wall is determined based on the tensile force and flexural lever arm of the main tension lap splice, including:

[0082] The flexural capacity of the lap splices of the main tensile reinforcement at the most unfavorable section of a diaphragm wall can be determined using the following formula:

[0083] M d =β1·α1·τ·l0·b·Z

[0084] Among them, M d β1·α1·τ·l0·b represents the flexural bearing capacity of the lap splice of the main tensile reinforcement in the diaphragm wall at the most unfavorable section; α1·τ·l0·b represents the tensile force of the lap splice of the main tensile reinforcement in the diaphragm wall; α1·τ·l0·b represents the punching shear failure strength of the lap splice; β1 represents the stress transfer reduction factor between the lap splice and the concrete; α1 represents the tensile-shear reduction factor of the concrete; τ represents the shear stress of the concrete; l0 represents the non-contact lap length of the lap splice of the primary and secondary reinforcements; b represents the width of the lap splice; Z represents the flexural arm of the lap splice of the main tensile reinforcement in the diaphragm wall.

[0085] Specifically, in this embodiment of the invention, the flexural bearing capacity of the steel reinforcement lap joints of the continuous wall can be determined by the following formula:

[0086] M d =β1·α·1·τ·l0·b·Z

[0087] Among them, M dZ represents the flexural bearing capacity of the lap splice of the main tensile reinforcement in the diaphragm wall; β1·α1·τ·l0·b represents the tensile force of the lap splice of the main tensile reinforcement in the diaphragm wall; α1·τ·l0·b represents the punching shear failure strength of the lap splice; β1 represents the stress transfer reduction factor between the lap splice and the concrete; α1 represents the concrete tensile-shear reduction factor; τ represents the concrete shear stress, which can be determined experimentally; l0 represents the non-contact lap length of the lap splice; b represents the width of the lap splice; Z represents the flexural lever arm of the main tensile lap splice in the diaphragm wall; optionally, if the concrete shear stress τ is determined using the following formula: Among them, f cu Given the compressive strength of the concrete cube, the flexural bearing capacity of the lap splice of the reinforcing steel in a continuous wall can be determined by the following formula:

[0088] The method described in the above embodiment determines the tensile force and punching shear failure strength of the main tensile lapped reinforcement of the diaphragm wall, and then accurately and quickly determines the bending bearing capacity of the reinforcement lap joint of the diaphragm wall based on the obtained tensile force and bending moment arm of the main tensile lapped reinforcement of the diaphragm wall. This achieves accurate determination of the bending capacity of the reinforcement lap joint of the diaphragm wall when the spacing of the lapped reinforcement is large.

[0089] In one embodiment, the method for determining the flexural bearing capacity of a rebar lap splice further includes:

[0090] Obtain the stress of the main tension lap splice reinforcement of the continuous wall;

[0091] The minimum cross-sectional area of ​​the lapped reinforcement in a continuous wall is determined based on the stress transfer reduction factor, the punching shear failure strength of the lapped reinforcement, and the stress of the main tensile lapped reinforcement in the continuous wall.

[0092] Specifically, the total tensile force of the main tension lap splice reinforcement can be determined by the following formula:

[0093] F s =f s ·A s =β1·F 冲切 ;

[0094] Among them, F 冲切 β1 represents the punching shear failure strength of the lapped steel reinforcement; f is the stress transfer reduction factor between the lapped steel reinforcement and the concrete; s Indicates the stress of the main tension lap splice steel bar measured in the experiment; A s This indicates the total cross-sectional area of ​​the main tension lapped reinforcement.

[0095] Based on the above formula, the stress transfer reduction factor β1 and the punching shear failure strength F of the lapped reinforcement are determined. 冲切 The stress f of the main tensile lap splice reinforcement of the continuous wall as measured by experiments sIn this case, the minimum cross-sectional area A of the lapped steel bars in the continuous wall can be accurately determined. s,min Optionally, the minimum cross-sectional area A of the lapped reinforcement in the continuous wall can be determined using the following formula. s,min :

[0096] A s,min =β1·F 冲切 / f s

[0097] Among them, f s This indicates the stress of the main tension lapped steel bar measured in the experiment.

[0098] Furthermore, the minimum cross-sectional area A of the lapped reinforcement in the diaphragm wall is determined. s,min This can be based on the determined minimum reinforcement cross-sectional area A of the lapped steel bars. s,min This provides a reference and assistance for the design of lapped rebar, making the design of lapped rebar more reasonable and accurate.

[0099] The method described above determines the minimum cross-sectional area of ​​the lap reinforcement of the continuous wall by using the stress transfer reduction factor, the punching shear failure strength of the lap reinforcement, and the stress of the main tensile lap reinforcement of the continuous wall. Based on the determined minimum cross-sectional area of ​​the lap reinforcement, the design of the lap reinforcement can be referenced and assisted, making the design of the lap reinforcement more reasonable and accurate.

[0100] In one embodiment, the method for determining the flexural bearing capacity of a rebar lap splice further includes:

[0101] Based on the flexural bearing capacity of the lap splice of the main tension reinforcement on the most unfavorable section of the diaphragm wall, and the first tensile force and the first flexural lever arm, determine the flexural bearing capacity of the lap splice of the main tension and auxiliary tension reinforcement on the most unfavorable section of the diaphragm wall; the first tensile force represents the tensile force corresponding to the auxiliary tension lap splice; the first flexural lever arm represents the flexural lever arm corresponding to the auxiliary tension lap splice.

[0102] Specifically, when the number of interlocking lapped steel meshes in a steel reinforcement lap joint increases, that is, when there are additional lapped steel bars in addition to the main compression and tension lapped steel bars on the most unfavorable section, the total tensile force Fsn of the additional lapped steel bars can be reduced according to the bending moment arm Zn of the additional lapped steel bars:

[0103] F sn =F s ·Z n / Z

[0104] The flexural bearing capacity of lap splices with different numbers of rows of reinforcing bars can then be determined using the following formula:

[0105]

[0106] Where Fsn is the total tensile force (first tensile force) of the auxiliary tension lap splices added from the nth row starting from the tension side on the most unfavorable section, excluding the main compression and main tension lap splices; Zn is the bending arm (first bending arm) of the auxiliary tension lap splices added from the nth row starting from the tension side on the most unfavorable section, excluding the main compression and main tension lap splices. In other words, when there are multiple tension lap splices in a diaphragm wall, it is necessary to determine the bending capacity of the lap splices of the main tension lap splices and the auxiliary tension lap splices. Therefore, the method of this embodiment is applicable to diaphragm walls with multiple tension lap splices, i.e., when there are main tension reinforcements and at least one auxiliary tension reinforcement, to determine the bending capacity of the lap splices of the reinforcements in the diaphragm wall.

[0107] The method described above accurately determines the flexural capacity of the steel lap joint when the number of steel mesh pieces in the lap joint increases, i.e., when there are additional auxiliary tensile steel bars in addition to the main compression and main tension lap joints on the most unfavorable section. This is based on the flexural bearing capacity of the main tension lap joint on the most unfavorable section of the continuous wall, the tensile force corresponding to the auxiliary tension lap joint, and the flexural lever arm corresponding to the auxiliary tension lap joint.

[0108] For example, the method for determining the flexural bearing capacity of a lapped ground tie joint with large-spacing rebar (the lap spacing of the rebar lap joint is greater than 5 times the diameter of the lapped rebar) provided in the embodiments of the present invention includes the following steps:

[0109] Step 1: On the most unfavorable calculation section of the non-contact lap joint of the steel reinforcement with large spacing, there are no other lap reinforcements except for the main compression and main tension lap reinforcements. Its flexural bearing capacity Md can be calculated by multiplying the total tensile force Fs of the lap reinforcement on the main tension side by the lever arm Z.

[0110] Step 2: Calculate the total tensile force of the lapped steel bars on the main tension side using the punching shear failure strength of the lapped steel bars, and simplify it to calculate the total tensile force Fs of the lapped steel bars on the main tension side in Step 1 using the single-sided concrete shear strength within the lap length range. It can also be reasonably transformed and applied to obtain the minimum reinforcement cross-sectional area As,min of the lapped steel bars.

[0111] Step 3: Determine the main bending resistance arm Z of the positive section under the ultimate bending moment of the steel lap splice in Step 1;

[0112] Step 4: Based on the total tensile force Fs and bending moment arm Z of the lapped reinforcement on the main tension side obtained in Steps 2 and 3, further determine the bending bearing capacity of the lapped joint of the auxiliary tension reinforcement in the continuous wall.

[0113] The method described in the above embodiments uses the concrete punching shear failure surface of the gap between the lapped reinforcing bars on the main tension side as the weak failure surface of the lapped joint, which is more consistent with the failure mode in the bending test of the lapped joint. The method for determining the bending capacity of the lapped joint using the embodiments of this application has fewer steps and can also consider the influence of non-contact lap length and non-contact lap spacing on the bending capacity of the lapped joint, which is simple and effective. It can also determine the minimum reinforcement cross-sectional area of ​​the lapped reinforcing bars to further improve the design of the lapped reinforcing bars. The bending design capacity of the lapped joint calculated by this method has a good predictive effect and is slightly lower than the test capacity (to the conservative level), which is very suitable as a method for determining the bending capacity of the lapped joint. In addition, it can be further extended to determine the bending design capacity of the lapped joint of the reinforcing bars in the continuous wall when there are multiple tensile reinforcing bars.

[0114] The following describes the device for determining the bending capacity of a rebar lap joint provided by the present invention. The device for determining the bending capacity of a rebar lap joint described below and the method for determining the bending capacity of a rebar lap joint described above can be referred to in correspondence with each other.

[0115] Figure 5 This is a structural schematic diagram of the device for determining the bending capacity of a rebar lap joint provided by the present invention. The device for determining the bending capacity of a rebar lap joint provided in this embodiment includes:

[0116] The acquisition module 710 is used to acquire the tensile force and bending moment arm of the main tension lap splice reinforcement on the most unfavorable section of the continuous wall;

[0117] Module 720 is used to determine the flexural bearing capacity of the lap splice of the main tension reinforcement on the most unfavorable section of the diaphragm wall based on the tensile force and bending moment arm of the main tension lap splice reinforcement.

[0118] Optionally, the acquisition module 710 is specifically used to: acquire the punching shear failure strength of the lapped steel bars and the stress transfer reduction factor between the lapped steel bars and the concrete;

[0119] Based on the punching shear failure strength of the lapped reinforcement and the stress transfer reduction coefficient between the lapped reinforcement and the concrete, the tensile force of the main tension lapped reinforcement on the most unfavorable section of the continuous wall is determined.

[0120] Optionally, the acquisition module 710 is specifically used to: acquire concrete shear stress, non-contact lap length of lapped reinforcing bars, lap width of lapped reinforcing bars, and concrete tensile-shear reduction coefficient;

[0121] The punching shear failure strength of the lapped steel bars is determined based on the concrete shear stress, the non-contact lap length of the lapped steel bars, the lap width of the lapped steel bars, and the concrete tensile-shear reduction coefficient.

[0122] Optionally, the acquisition module 710 is specifically used to: acquire the height of the concrete flexural section, the thickness of the protective layer of the main tensile reinforcement, and the height of the compression zone of the concrete section;

[0123] The bending arm of the main tensile lapped reinforcement on the most unfavorable section of the diaphragm wall is determined based on the height of the concrete bending section, the thickness of the protective layer of the main tensile reinforcement, and the height of the compression zone of the concrete section.

[0124] Optionally, the determining module 720 is specifically used to: determine the flexural bearing capacity of the lap joints of the main tensile reinforcement at the most unfavorable section of the continuous wall using the following formula:

[0125] M d =β1·α1·τ·l0·b·Z

[0126] Among them, M d β1·α1·τ·l0·b represents the flexural bearing capacity of the lap splice of the main tensile reinforcement in the diaphragm wall at the most unfavorable section; α1·τ·l0·b represents the tensile force of the lap splice of the main tensile reinforcement in the diaphragm wall; α1·τ·l0·b represents the punching shear failure strength of the lap splice; β1 represents the stress transfer reduction factor between the lap splice and the concrete; α1 represents the tensile-shear reduction factor of the concrete; τ represents the shear stress of the concrete; l0 represents the non-contact lap length of the lap splice; b represents the width of the lap splice; Z represents the flexural arm of the lap splice of the main tensile reinforcement in the diaphragm wall.

[0127] Optionally, the determining module 720 is specifically used to: obtain the stress of the main tension lap splice reinforcement of the continuous wall;

[0128] The minimum cross-sectional area of ​​the lapped reinforcement in a continuous wall is determined based on the stress transfer reduction factor, the punching shear failure strength of the lapped reinforcement, and the stress of the main tensile lapped reinforcement in the continuous wall.

[0129] Optionally, the determining module 720 is specifically used to: determine the flexural bearing capacity of the main tension and auxiliary tension reinforcement lap joints on the most unfavorable section of the continuous wall based on the flexural bearing capacity of the main tension reinforcement lap joints on the most unfavorable section of the continuous wall and the first tensile force and the first flexural lever arm; the first tensile force represents the tensile force corresponding to the auxiliary tension lap joint; the first flexural lever arm represents the flexural lever arm corresponding to the auxiliary tension lap joint.

[0130] The apparatus of this invention is used to execute the method in any of the foregoing method embodiments, and its implementation principle and technical effect are similar, so they will not be described again here.

[0131] Figure 6A schematic diagram of the physical structure of an electronic device is provided. This electronic device may include a processor 810, a communications interface 820, a memory 830, and a communication bus 840. The processor 810, communications interface 820, and memory 830 communicate with each other via the communication bus 840. The processor 810 can invoke logical instructions in the memory 830 to execute a method for determining the flexural bearing capacity of a rebar lap joint. This method includes: obtaining the tensile force and flexural lever arm of the main tension lap joint rebar at the most unfavorable section of the continuous wall; and determining the flexural bearing capacity of the main tension lap joint rebar at the most unfavorable section of the continuous wall based on the tensile force and flexural lever arm of the main tension lap joint rebar.

[0132] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0133] On the other hand, the present invention also provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, wherein when the program instructions are executed by a computer, the computer is able to execute the method for determining the flexural bearing capacity of the steel reinforcement lap joint provided by the above methods, the method comprising: obtaining the tensile force and flexural lever arm of the main tension lap joint steel reinforcement at the most unfavorable section of the continuous wall; and determining the flexural bearing capacity of the main tension lap joint steel reinforcement at the most unfavorable section of the continuous wall based on the tensile force and flexural lever arm of the main tension lap joint steel reinforcement.

[0134] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described methods for determining the flexural bearing capacity of the steel reinforcement lap joints, the method comprising: obtaining the tensile force and flexural lever arm of the main tension lap joint steel reinforcement at the most unfavorable section of the diaphragm wall; and determining the flexural bearing capacity of the main tension lap joint steel reinforcement at the most unfavorable section of the diaphragm wall based on the tensile force and flexural lever arm of the main tension lap joint steel reinforcement.

[0135] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0136] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of determining the flexural capacity of a lap splice joint of reinforcing steel, characterised by, The method comprises the following steps: obtaining the tensile force and the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall; the lap spacing in the continuous wall is greater than or equal to 5 times the diameter of the steel bar; wherein, in the case that there is only one tensile lap steel bar in the continuous wall, the tensile lap steel bar is the main tensile lap steel bar; determining the bending capacity of the main tensile lap steel bar joint on the most unfavorable section of the continuous wall according to the tensile force and the bending moment arm of the main tensile lap steel bar; the method for obtaining the tensile force and the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall comprises the following steps: obtaining the punching shear failure strength of the lap steel bar and the stress transfer reduction coefficient between the lap steel bar and the concrete; determining the tensile force of the main tensile lap steel bar on the most unfavorable section of the continuous wall according to the punching shear failure strength of the lap steel bar and the stress transfer reduction coefficient between the lap steel bar and the concrete; the method for obtaining the punching shear failure strength of the lap steel bar comprises the following steps: obtaining the shear stress of the concrete, the non-contact lap length of the lap steel bar, the width of the lap steel bar and the concrete tension shear reduction coefficient; determining the punching shear failure strength of the lap steel bar according to the shear stress of the concrete, the non-contact lap length of the lap steel bar, the width of the lap steel bar and the concrete tension shear reduction coefficient; the method for obtaining the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall comprises the following steps: obtaining the bending section height of the concrete, the cover thickness of the main tensile steel bar and the height of the compression zone of the concrete section; determining the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall according to the bending section height of the concrete, the cover thickness of the main tensile steel bar and the height of the compression zone of the concrete section; the method for determining the bending capacity of the main tensile lap steel bar joint on the most unfavorable section of the continuous wall according to the tensile force and the bending moment arm of the main tensile lap steel bar comprises the following steps: the bending capacity of the main tensile lap steel bar joint on the most unfavorable section of the continuous wall is determined by using the following formula: wherein, represents the flexural capacity of the lap joint of the main tensile reinforcement on the most unfavorable cross section of the continuous wall; said represents the tensile force of the main tensile lap reinforcement of the continuous wall; said represents the punching shear failure strength of the lap reinforcement; β1 represents the stress transfer reduction factor between the lap reinforcement and the concrete; represents the concrete tension-shear reduction factor; represents the concrete shear stress; represents the non-contact lap length of the lap reinforcement; b represents the lap reinforcement width; Z represents the flexural arm of the main tensile lap reinforcement of the continuous wall.

2. A device for determining the flexural capacity of a lap splice joint of reinforcing steel, characterised in that, the method for determining the bending capacity of the lap joint of the steel bar according to the application of claim 1 comprises the following steps: an obtaining module is used to obtain the tensile force and the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall; the lap spacing in the continuous wall is greater than or equal to 5 times the diameter of the steel bar; wherein, in the case that there is only one tensile lap steel bar in the continuous wall, the tensile lap steel bar is the main tensile lap steel bar; the method for obtaining the tensile force and the bending moment arm of the main tensile lap steel bar on the most unfavorable section of the continuous wall comprises the following steps: obtaining the punching shear failure strength of the lap steel bar and the stress transfer reduction coefficient between the lap steel bar and the concrete; determining the tensile force of the main tensile lap steel bar on the most unfavorable section of the continuous wall according to the punching shear failure strength of the lap steel bar and the stress transfer reduction coefficient between the lap steel bar and the concrete; the method for obtaining the punching shear failure strength of the lap steel bar comprises the following steps: obtaining the shear stress of the concrete, the non-contact lap length of the lap steel bar, the width of the lap steel bar and the concrete tension shear reduction coefficient; determining the punching shear failure strength of the lap steel bar according to the shear stress of the concrete, the non-contact lap length of the lap steel bar, the width of the lap steel bar and the concrete tension shear reduction coefficient; The method comprises the following steps: acquiring the flexural force arm of the main tensile lap joint steel bars on the most unfavorable section of the continuous wall, comprising: acquiring the concrete flexural section height, the main tensile steel bar protective layer thickness and the concrete section compression zone height; determining the flexural force arm of the main tensile lap joint steel bars on the most unfavorable section of the continuous wall according to the concrete flexural section height, the main tensile steel bar protective layer thickness and the concrete section compression zone height; determining the flexural bearing capacity of the main tensile steel bar lap joint on the most unfavorable section of the continuous wall according to the tensile force and the flexural force arm of the main tensile lap joint steel bars; the flexural bearing capacity of the main tensile steel bar lap joint on the most unfavorable section of the continuous wall is determined according to the tensile force and the flexural force arm of the main tensile lap joint steel bars, comprising: wherein, represents the flexural capacity of the lap joint of the main tensile reinforcement on the most unfavorable cross section of the continuous wall; said represents the tensile force of the main tensile lap reinforcement of the continuous wall; said represents the punching shear failure strength of the lap reinforcement; β1 represents the stress transfer reduction factor between the lap reinforcement and the concrete; represents the concrete tension-shear reduction factor; represents the concrete shear stress; represents the non-contact lap length of the lap reinforcement; b represents the lap reinforcement width; Z represents the flexural arm of the main tensile lap reinforcement of the continuous wall.

3. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, the flexural bearing capacity of the main tensile steel bar lap joint on the most unfavorable section of the continuous wall is determined by using the following formula:

4. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The processor executes the program to realize the flexural bearing capacity determination method of the steel bar lap joint as claimed in claim 1. The computer program is executed by the processor to realize the flexural bearing capacity determination method of the steel bar lap joint as claimed in claim 1.

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