A method for predicting failure mode of plate column joint
By constructing a test database for slab-column joints and establishing a discriminant characteristic parameter model, the failure mode of slab-column joints is determined by the strain ratio of the longitudinal tensile reinforcement in the slab. This solves the problem of inconsistent failure mode determination in existing technologies and achieves high-precision failure mode prediction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2023-12-18
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies are insufficient to uniformly determine the failure mode of slab-column joints, and existing methods have limitations, failing to accurately determine failure modes when bearing capacity test values are unknown.
By constructing a test database for slab-column joints, the ratio of the tensile longitudinal reinforcement strain εs to the yield strain εy of the tensile longitudinal reinforcement in the slab is determined as the discrimination index. A calculation model for the discrimination characteristic parameters and the discrimination criteria are established to predict the failure mode of slab-column joints.
It achieves accurate prediction of failure modes of plate-column joints, simplifies the discrimination process, improves prediction accuracy, and avoids the shortcomings of existing methods.
Smart Images
Figure CN117709105B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of civil engineering technology, specifically relating to a method for predicting the failure mode of a slab-column joint. Background Technology
[0002] Slab-column joints in slab-column structures need to transfer bending moment and shear force between the slab and column, and are in a state of combined bending and shear stress. Influenced by factors such as material parameters, geometric dimensions, span ratio, and the longitudinal reinforcement ratio of the slab tension bars, slab-column joints may experience punching shear failure, flexural-punching failure, and bending failure. Slab-column joints experiencing punching shear failure exhibit a smaller bending effect and a more significant punching shear effect, making punching shear failure unpredictable and brittle. In punching shear failure, the longitudinal reinforcement of the slab does not yield at the column edge, and a failure cone forms within the slab. Flexural-punching failure is the result of the combined effects of the highly concentrated bending and punching shear effects around the column, representing a failure state intermediate between bending and punching shear failure. In flexural-punching failure, bending cracks first form along the column perimeter on the tensile surface of the slab, followed by radial cracks extending outwards from the column perimeter. Subsequently, the tensile reinforcement of the slab yields at the column edge, and a failure cone forms within the slab. Bending failure is dominated by the bending effect and belongs to ductile failure. In plate-column joints that experience bending failure, bending cracks first appear on the tension surface of the plate, and then the cracks propagate until they form plastic hinge lines, accompanied by the yielding of a large area of the tensile longitudinal reinforcement in the plate. Ultimately, due to the excessive crack width and deformation of the plate, a mechanism is formed and it can no longer bear the load. It can be seen that the stress performance and failure phenomena of plate-column joints with different failure modes are quite different.
[0003] Scholars both domestically and internationally have proposed methods for identifying the failure modes of slab-column joints from different perspectives. However, a unified understanding of how to identify these failure modes remains lacking, and existing methods all have certain limitations. For example, the Ramdane method can only identify the failure mode of a slab-column joint when the test values of its bearing capacity are known; Wang Anbao's discrimination formula is only applicable to punching shear failure and flexural punching failure of slab-column joints; and the Gesund method contradicts the requirement that the tensile longitudinal reinforcement of the slab does not yield during punching shear failure. Furthermore, my country's "Code for Design of Concrete Structures" GB50010-2010 does not provide criteria for slab-column joint modes, only specifying the formula for calculating the punching shear bearing capacity of slab-column joints. Therefore, it is necessary to develop a method for predicting the failure modes of slab-column joints to overcome the technical deficiencies of existing methods and provide a foundation for calculating the bearing capacity of slab-column joints with different failure modes. Summary of the Invention
[0004] The purpose of this invention is to provide a method for predicting the failure mode of a plate-column joint. This method considers comprehensive factors and is simple to apply. Only the relevant parameters of the plate-column joint need to be input to predict the failure mode, thus overcoming the shortcomings of existing methods.
[0005] The present invention provides a method for predicting the failure mode of a plate-column joint, comprising the following steps:
[0006] Step 1: Construct a test database for slab-column joints to determine the strain ε of the tensile longitudinal reinforcement in the slab. s Yield strain ε of longitudinal tensile reinforcement in plate y The ratio is a quantitative indicator for determining the failure mode of a plate-column joint;
[0007] Step 2: Establish the discriminant characteristic parameters for plate-column joint failure modes Computational model;
[0008] Step 3: Establish the criteria for determining the failure mode of plate-column joints.
[0009] Beneficial effects:
[0010] This invention, based on a plate-column joint test database, analyzes the distribution patterns of discriminant characteristic parameters for plate-column joint failure modes, establishes discrimination criteria for plate-column joint failure modes, and thus achieves prediction of plate-column joint failure modes. The proposed plate-column joint failure mode discrimination method considers comprehensive factors and is simple to apply. Only the relevant parameters of the plate-column joint need to be input to predict the failure mode. Attached Figure Description
[0011] Figure 1 Distribution diagram of the discriminant characteristic parameters for plate-column joints undergoing punching failure;
[0012] Figure 2 Distribution diagram of the characteristic parameters for identifying plate-column joints in bending-impact failure;
[0013] Figure 3 Distribution diagram of the characteristic parameters for identifying plate-column joints undergoing bending failure. Detailed Implementation
[0014] Specific Implementation Method 1: The plate-column joint failure mode prediction method described in this implementation method includes the following steps:
[0015] Step 1: Construct a test database for slab-column joints to determine the strain ε of the tensile longitudinal reinforcement in the slab. s Yield strain ε of longitudinal tensile reinforcement in plate y The ratio is a quantitative indicator for determining the failure mode of a plate-column joint;
[0016] Step 2: Establish the discriminant characteristic parameters for plate-column joint failure modes Computational model;
[0017] Step 3: Establish the criteria for determining the failure mode of plate-column joints.
[0018] In this embodiment, theoretical analysis suggests that the strain ε of the tensile longitudinal reinforcement in the slab at the failure of the slab-column joint is...s With the yield strain ε of the tensile longitudinal reinforcement y The ratio of the bending and punching shear effects at the slab-column joint failure can reflect the relative magnitudes of these effects, thus this ratio is used as a quantitative indicator for determining the failure mode of the slab-column joint. Therefore, the strain ε of the longitudinal tensile reinforcement in the slab at the slab-column joint failure is... s Its yield strain ε y The ratio is defined as a discriminant characteristic parameter for the failure mode of a plate-column joint.
[0019] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that step one involves collecting plate-column joint failure test data from literature to construct a plate-column joint test database. Other steps and parameters are the same as in Specific Implementation Method One.
[0020] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method Two in that each set of data in the experimental database should include the axial compressive strength f of concrete. c Column cross-section dimension c, effective height of slab cross-section h0, span a, maximum aggregate size of concrete d g ρ, the tensile longitudinal reinforcement ratio of the slab, and E, the elastic modulus of the tensile longitudinal reinforcement of the slab. s Yield strength f of longitudinal reinforcement in slab under tension y The information includes the side length B of the plate. Other steps and parameters are the same as in Specific Implementation Method Two.
[0021] The term "crossing 'a'" refers to the distance from the loading point to the edge of the column.
[0022] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that step two establishes the discriminative characteristic parameters for the failure mode of the plate-column joint. The calculation model is performed in the following steps:
[0023] ① The rotation angle ψ of the plate when the plate-column joint fails is calculated based on the critical diagonal crack theory. u ;
[0024] ② Set the number of diagonal cracks at the slab-column joint failure to 3, and calculate the strain ε of the tensile longitudinal reinforcement in the slab. s ;
[0025] ③Based on the yield strength f of the longitudinal tensile reinforcement in the slab y Elastic modulus E of longitudinal tensile reinforcement in slab s The yield strain ε of the longitudinal tensile reinforcement in the plate was calculated. y ;
[0026] ④ Through the strain ε of the longitudinal tensile reinforcement in the plate s Yield strain ε of longitudinal tensile reinforcement in plate y The discriminant characteristic parameters of the failure mode of the plate-column joint were calculated. The other steps and parameters are the same as in Specific Implementation Method 1.
[0027] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that step ① calculates the rotation angle ψ of the plate when the plate-column joint fails. u The expression is as follows:
[0028] The other steps and parameters are the same as in Specific Implementation Method Four.
[0029] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Four in that step ② calculates the strain ε of the tensile longitudinal reinforcement in the plate. s The expression is as follows:
[0030] The other steps and parameters are the same as in Specific Implementation Method Four.
[0031] This embodiment, through analysis of punching, bending, and flexural test results of the slab-column joint, found that the strain of the tensile longitudinal reinforcement in the slab does not change significantly within the failure cone of the slab-column joint, and the angle of the diagonal crack at different locations in the slab also does not change significantly. Therefore, it is considered that the strain of the tensile longitudinal reinforcement in the slab is the same within the failure cone of the slab-column joint, and the angle of the diagonal crack at different locations in the slab is the same.
[0032] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Four in that step ③ calculates the yield strain ε of the tensile longitudinal reinforcement in the plate. y The expression is as follows:
[0033] The other steps and parameters are the same as in Specific Implementation Method Four.
[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Four in that step ④ calculates the discriminant characteristic parameters of the plate-column joint failure mode. The expression is as follows:
[0035] The other steps and parameters are the same as in Specific Implementation Method Four.
[0036] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that step four divides the plate-column nodes into plate-column nodes that experience punching failure, plate-column nodes that experience bending-punching failure, and plate-column nodes that experience bending failure, thereby deriving the discriminative characteristic parameters of plate-column nodes with different failure modes. Distribution patterns; based on discriminant feature parameters The distribution pattern is determined, thus providing criteria for judging punching failure, flexural punching failure, and bending failure at plate-column joints. Other steps and parameters are the same as in Specific Implementation Method 1.
[0037] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that it determines the characteristic parameters. When the value is less than 1, punching shear failure occurs at the plate-column joint; discrimination characteristic parameter When the value is between 1 and 2, the plate-column joint experiences bending impact failure; determine the characteristic parameters. When the value is greater than 2, bending failure occurs at the plate-column joint. Other steps and parameters are the same as in specific implementation method nine.
[0038] The beneficial effects of the present invention are verified through the following embodiments:
[0039] Example: The method for predicting the failure mode of a plate-column joint includes the following steps:
[0040] Step 1: Collect and select 261 sets of slab-column joint failure test data from the literature to construct a slab-column joint test database, and determine the strain ε of the tensile longitudinal reinforcement in the slab. s Yield strain ε of longitudinal tensile reinforcement in plate y The ratio is a quantitative indicator for determining the failure mode of slab-column joints; each set of data in the experimental database should include the axial compressive strength f of the concrete. c Column cross-section dimension c, effective height of slab cross-section h0, span a, maximum aggregate size of concrete d g ρ, the tensile longitudinal reinforcement ratio of the slab, and E, the elastic modulus of the tensile longitudinal reinforcement of the slab. s Yield strength f of longitudinal reinforcement in slab under tension y And information about the side length B of the board;
[0041] Step 2: Establish the discriminant characteristic parameters for plate-column joint failure modes Computational model:
[0042] ① The rotation angle ψ of the plate when the plate-column joint fails is calculated based on the critical diagonal crack theory. u ; Calculate the rotation angle ψ of the plate when the column joint fails. u The expression is as follows:
[0043]
[0044] ② Set the number of diagonal cracks at the slab-column joint failure to 3, and calculate the strain ε of the tensile longitudinal reinforcement in the slab. s ; Calculate the strain ε of the longitudinal tensile reinforcement in the slab. s The expression is as follows:
[0045]
[0046] ③Based on the yield strength f of the longitudinal tensile reinforcement in the slab y Elastic modulus E of longitudinal tensile reinforcement in slab s The yield strain ε of the longitudinal tensile reinforcement in the plate was calculated. y ; Calculate the yield strain ε of the tensile longitudinal reinforcement in the slab.y The expression is as follows:
[0047]
[0048] ④ Through the strain ε of the longitudinal tensile reinforcement in the plate s Yield strain ε of longitudinal tensile reinforcement in plate y The discriminant characteristic parameters of the failure mode of the plate-column joint were calculated. Calculate the discriminant characteristic parameters of plate-column joint failure modes. The expression is as follows:
[0049]
[0050] Step 3: Divide the plate-column joints into three categories: those experiencing punching shear failure, those experiencing flexural-punching failure, and those experiencing bending failure, thereby deriving the discriminative characteristic parameters for plate-column joints with different failure modes. Distribution patterns; based on discriminant feature parameters The distribution pattern is used to determine the criteria for punching failure, flexural punching failure, and bending failure at plate-column joints; when the characteristic parameters are used for discrimination... When the value is less than 1, punching shear failure occurs at the plate-column joint; discrimination characteristic parameter When the value is between 1 and 2, the plate-column joint experiences bending impact failure; determine the characteristic parameters. When the value is greater than 2, the plate-column joint will experience bending failure.
[0051] Step 4: Determine the failure mode of the slab-column joint to be judged;
[0052] (1) Select three more sets of plate-column nodes to be judged, denoted as S1, S2 and S3 respectively, and calculate the discrimination characteristic parameters of the failure mode of the plate-column nodes to be judged according to step two. For plate-column nodes S1, S2, and S3, the calculated discriminant feature parameters are... The values are 0.78, 1.14, and 2.09, respectively.
[0053] (2) Based on the criteria for determining the failure modes of the plate-column joints in step three, determine the failure modes of the plate-column joints to be determined. According to the criteria for determining the failure modes of the plate-column joints, the failure modes of plate-column joints S1, S2 and S3 are punching shear failure, bending punching failure and bending failure, respectively.
[0054] (3) According to the test results, the failure modes of plate-column nodes S1, S2 and S3 are punching failure, bending punching failure and bending failure, respectively, which are consistent with the failure modes predicted by the method of the present invention.
[0055] Step 5: Compare and verify the accuracy of the method of the present invention in predicting the failure mode of plate-column nodes.
[0056] (1) Based on the Geusnd method for determining the failure mode of plate-column joints, 261 failure modes of plate-column joints in the plate-column joint test database were determined. The Geusnd method correctly predicted the failure modes of 124 plate-column joints with punching failure, 52 plate-column joints with bending-punching failure, and 9 plate-column joints with bending failure.
[0057] (2) According to the method for predicting the failure mode of plate-column joints of the present invention, 261 sets of failure modes of plate-column joints in the plate-column joint test database were determined. The method of the present invention correctly predicted 133 sets of failure modes of plate-column joints with punching failure, 86 sets of failure modes of plate-column joints with bending punching failure, and 9 sets of failure modes of plate-column joints with bending failure.
[0058] (3) The accuracy rates of the Geusnd method in predicting the failure modes of plate-column joints for punching, flexural-punching, and bending failures were 89.9%, 46.4%, and 81.8%, respectively, while the accuracy rates of the method of this invention in predicting the failure modes of plate-column joints for punching, flexural-punching, and bending failures were 96.4%, 76.8%, and 81.8%, respectively. The proportion of plate-column joints correctly predicted by the Geusnd method was 70.8%, while the proportion of plate-column joints correctly predicted by the method of this invention was 87.4%.
[0059] Comparison table of plate-column joint failure modes predicted by the Gesund method and those obtained from actual measurements:
[0060]
[0061] Comparison table of predicted and measured failure modes for plate-column joints in this embodiment:
[0062]
[0063] Therefore, the method of the present invention can more accurately predict the failure mode of plate-column joints and is easy to apply. Only the relevant parameters of the plate-column joint need to be input to predict the failure mode, and it avoids the technical defects of existing methods for determining the failure mode of plate-column joints.
Claims
1. A method for predicting the failure mode of a plate-column joint, characterized in that... The method for predicting the failure mode of a plate-column joint includes the following steps: Step 1: Construct a test database for slab-column joints to determine the strain ε of the tensile longitudinal reinforcement in the slab. s Yield strain ε of longitudinal tensile reinforcement in plate y The ratio is a quantitative indicator for determining the failure mode of a plate-column joint; Each set of data in the experimental database should include the axial compressive strength f of concrete. c Column cross-section dimension c, effective height of slab cross-section h0, span a, maximum aggregate size of concrete d g ρ, the tensile longitudinal reinforcement ratio of the slab, and E, the elastic modulus of the tensile longitudinal reinforcement of the slab. s Yield strength f of longitudinal reinforcement in slab under tension y And information about the side length B of the board; Step 2: Establish a calculation model for the discriminant characteristic parameter φ of the plate-column joint failure mode. This will be carried out according to the following steps: ① The rotation angle ψ of the plate when the plate-column joint fails is calculated based on the critical diagonal crack theory. u ; ② Set the number of diagonal cracks at the slab-column joint failure to 3, and calculate the strain ε of the tensile longitudinal reinforcement in the slab. s ; ③Based on the yield strength f of the longitudinal tensile reinforcement in the slab y Elastic modulus E of longitudinal tensile reinforcement in slab s The yield strain ε of the longitudinal tensile reinforcement in the plate was calculated. y ; ④ Through the strain ε of the longitudinal tensile reinforcement in the plate s Yield strain ε of longitudinal tensile reinforcement in plate y The discriminant characteristic parameter φ of the plate-column joint failure mode is calculated; the expression of the discriminant characteristic parameter φ is as follows: ； Step 3: Establish the discrimination criteria for the failure modes of plate-column joints; classify plate-column joints into those that undergo punching shear failure, those that undergo flexural punching failure, and those that undergo bending failure, thereby obtaining the distribution law of the discrimination characteristic parameter φ for plate-column joints with different failure modes; based on the distribution law of the discrimination characteristic parameter φ, the discrimination criteria for punching shear failure, flexural punching failure, and bending failure of plate-column joints are given.
2. The method for predicting the failure mode of a plate-column joint according to claim 1, characterized in that... Step 1: Collect plate-column joint failure test data from the literature to construct a plate-column joint test database.
3. The method for predicting the failure mode of a plate-column joint according to claim 1, characterized in that... Step ① Calculate the rotation angle ψ of the plate when the plate-column joint fails. u The expression is as follows: 。 4. The method for predicting the failure mode of a plate-column joint according to claim 1, characterized in that... Step 2: Calculate the strain ε of the tensile longitudinal reinforcement in the slab. s The expression is as follows: 。 5. The method for predicting the failure mode of a plate-column joint according to claim 1, characterized in that... Step ③ Calculate the yield strain ε of the tensile longitudinal reinforcement in the slab. y The expression is as follows: 。 6. The method for predicting the failure mode of a plate-column joint according to claim 1, characterized in that... When the discriminant characteristic parameter φ is less than 1, the plate-column node undergoes punching failure; When the discriminant characteristic parameter φ is between 1 and 2, the plate-column joint undergoes bending impact failure. When the discriminant characteristic parameter φ is greater than 2, the plate-column joint will experience bending failure.