Method for determining shear stiffness of bolt shear connector with preformed hole

Abstract

The invention relates to a method for determining the shear stiffness of a bolt shear connector with preformed holes. The method comprises the following steps: acquiring a plurality of load-slip curves of the bolt shear connector with preformed holes on the basis of test data; and dividing each load-slip curve into a friction section, a slip section and a curve section, and respectively determining the shear stiffness of each section. In the determination of the fitting curve parameter beta of the curve segments, presetting the initial value of the fitting curve parameter, calculating the average value of the maximum shear loads of all the curve segments, taking the average value of the maximum shear loads as the maximum shear loads of the curve segments, and calculating the average value of the maximum slippage of all the curve segments; according to the method, the maximum sliding value of the curve segment is calculated, the average value of the maximum sliding is used as the maximum load sliding value of the curve segment, linear programming iteration solving is conducted on the energy error obtained through the area difference based on energy balance so as to determine the fitting curve parameter beta, dependence on experience is reduced, applicability is higher, theoretical guidance is given, and a new direction is pointed out for corresponding research.

Description

Technical Field

[0001] The invention relates to the technical field of determining the shear stiffness of a shear connector in a bridge project, and in particular to a method for determining the shear stiffness of a shear connector with bolts having reserved holes. Background Art

[0002] Steel-concrete composite beam refers to a beam structure that uses steel and concrete as two materials, and connects the steel beam and concrete into a whole through shear connectors. The two beams are jointly stressed, making full use of the material properties of steel tensile resistance and concrete compressive resistance, while ensuring the effective utilization of materials. Common forms of shear connectors include Figure 1 As shown in the figure, the shear connector 01 is a key component for the coordinated work of the steel beam 03 and the concrete slab 02, which directly affects the transmission of shear stress at the junction of the steel beam 03 and the concrete slab 02. The shear stiffness is defined as the stress required to cause a unit shear deformation of the shear connector 01, which directly reflects the ability of the shear connector to resist shear deformation. The shear connector 01 includes studs, bolts and perforated steel plates (PBL) connectors. Please refer to Figure 2 The load-slip curves of the three are roughly the same, with the ordinate being the shear load P and the abscissa being the slip s, where P u and u Represent the maximum shear load and maximum slip respectively. The curve includes the approximate linear elastic stage 04, the plastic stage 05 and the descending stage 06. At present, the method for confirming the shear stiffness of shear connectors at home and abroad is generally based on the derivation of the load-slip curve. That is, the secant slope at a certain percentage of the ultimate shear load or equivalent slip on the load-slip curve is used. For example, the European standard 4 stipulates that the stiffness calculation method of the shear connector is the secant slope at 0.9 times the maximum load.

[0003] However, the premise of using this type of method is that the load-slip curve of the component is known, that is, a push-out test or direct shear test is required, and the load-slip curve characteristics of different shear connectors vary greatly. This method relies on the test conditions, experience and subjective judgment of different researchers, lacks unified theoretical guidance, and can only generally calculate a shear stiffness as a reference, which has poor applicability. The example provided by Eurocode 4 is a stud connector. Before reaching the maximum load, the curve characteristic is a monotonically increasing line, and its relative slip is generally less than 9mm. However, for bolt or PBL connectors, there are problems such as large relative slip and a plateau in the rising stage. This type of formula is not universal. In addition, there are very few studies on the shear stiffness of shear connectors at home and abroad, especially for bolts and PBL connectors. It is necessary to adopt a unified framework to establish a more universal and reasonable shear stiffness calculation method for shear connectors.

[0004] In the current research, in the study of load-slip behavior, some schemes use nonlinear regression analysis of push-out test results and theoretical analysis using the classical Ollgaard constitutive law to obtain exponential load-slip relationship expressions for stud shear connectors and single shear connectors. Some schemes propose load-slip relationship theoretical models for prefabricated steel-thin-layer ultra-high performance concrete large-diameter group stud connectors. These schemes are all studies on the load-slip relationship of studs.

[0005] In some schemes, the mechanical properties of bolted connections of steel-steel fiber reinforced concrete composite beams were studied by experiments and finite element models, and design formulas for predicting the load-slip relationship of high-strength bolted connections were proposed. In some schemes, the characteristics of the three stages of the load-slip relationship of bolted shear connections were analyzed, and a simplified load-slip model of 16mm diameter bolted shear connections was established. These schemes are all studies on the load-slip relationship of bolts.

[0006] In some schemes, the normalization method is used to analyze the influence of the shear stiffness of the concrete tenon and the tensile strength of the through steel bars on the load-slip relationship of the PBL connector at each working stage, and the load-slip relationship formula of the whole loading process is proposed. It is believed that the load-slip curve can be divided into elastic section, elastic-plastic section and strengthening section. In some schemes, the force mechanism of the hybrid structure PBL shear key and its important influencing factors are deeply analyzed, and the ultimate bearing capacity calculation formula of the hybrid structure PBL shear key is proposed. The characteristic load and corresponding slip under the elastic limit and yield limit of the PBL shear key are given, and finally the load-slip characteristic curve of the whole loading process of the PBL shear key is obtained. These schemes are all studies on the load-slip relationship of PBL.

[0007] In the study of shear stiffness, in some schemes, the tangent modulus method at 0.5 times the shear limit load on the load-slip curve was proposed through data analysis of 116 push-out test results. In some schemes, the deformation characteristics and stress mechanism of the studs were analyzed through 40 push-out tests, and the calculation formula of the shear stiffness of the stud shear connector with respect to the elastic modulus of concrete, the elastic modulus of the stud and the diameter of the stud was proposed through zero-intercept linear regression analysis. In some schemes, the aperture of the perforated plate, the strength and elastic modulus of concrete, and the diameter, strength and elastic modulus of the steel bars in the hole were used as variable parameters, and 60 model tests on the shear stiffness of the perforated plate connectors were carried out; the relationship between the ratio of the slope of the tangent to the secant of the shear relative slip curve of each model specimen and the relative slip was analyzed, and a method for determining the shear stiffness of the perforated plate connector was proposed; the elastic foundation beam method was used to analyze the shear mechanism of the concrete and steel bars in the hole, and the theoretical calculation formula for the shear stiffness of the perforated plate connector was derived; based on theoretical analysis and 123 model tests in various countries, a calculation formula for the shear stiffness of PBL connectors with and without steel bars in the hole was proposed.

[0008] However, although the current solutions for determining the shear stiffness of shear connectors are mostly based on experimental experience, they are more dependent on experience and lack theoretical guidance. In particular, for the determination of the shear stiffness of shear connectors with reserved bolt holes, due to the complexity of the force, they are more dependent on experience and need to be obtained based on each test, making it difficult to provide a determination solution that can be applied to various situations. Summary of the invention

[0009] The technical problem to be solved by the present application is to provide a method for determining the shear stiffness of a shear connector with bolts having reserved holes, which has the characteristic of being more applicable in the method of confirming the shear stiffness of the connector.

[0010] In a first aspect, an embodiment provides a method for determining the shear stiffness of a bolt shear connector with a reserved hole, comprising: Based on the test data, multiple load-slip curves of bolted shear connectors with pre-reserved holes are obtained; Each load-slip curve is divided into friction section, sliding section and curve section, and the shear stiffness of the friction section, sliding section and curve section is determined respectively; the friction section is formed by friction force resisting shear load, which is linear; the sliding section is composed of nearly horizontal horizontal lines produced by sliding after the friction force fails; the curve section is formed by the interaction between bolts and concrete to resist shear load, which is nonlinear; For curve segments, based on the curve fitting formula The corresponding load-slip curve is used to solve the shear stiffness; where P q represents the shear load of the curve segment, P qu Indicates the maximum shear load of the curve segment, P h represents the shear load corresponding to the end of the slip segment, s represents the relative slip between the concrete slab and the steel beam, and s h represents the relative slip corresponding to the end of the slip segment, represents the fitting curve parameter, and e represents the natural number base; Among them, the fitting curve parameters Methods for determining include: Preset initial values ​​of fitting curve parameters ; Calculate the average value of the maximum shear loads of all curve segments in the multiple load-slip curves, and use the average value of the maximum shear loads as the curve segment maximum shear load P qu ; Calculate the average value of the maximum slip of all curve segments in the multiple load-slip curves, and use the average value of the maximum slip as the maximum load slip of the curve segment s u ; Calculate the distance between each curve segment and the s-axis [s h,n,s u,n ] segment is taken as the first area, and n represents the index of the load-slip curve; Calculation formula The curve and the s-axis [s h ,s u ] is taken as the second area; calculating the absolute value of the difference between the second area and each first area; calculating an energy error based on each of the absolute values; Based on linear programming iterative solution, the energy error is minimized. The solution is used as the fitting curve parameter The value of .

[0011] In one embodiment, the average value of the maximum shear loads of all curve segments in the multiple load-slip curves is calculated, and the average value of the maximum shear loads is used as the maximum shear load P of the curve segment. qu ,include: (7) Among them, P qu,n represents the maximum shear load of the curve segment of the nth load-slip curve, N represents the total number of load-slip curves, 1≤n≤N; The calculation of the average value of the maximum slip of all curve segments in the plurality of load-slip curves is performed, and the average value of the maximum slip is used as the maximum load slip of the curve segment s u ,include: (8) Among them, s u,n represents the maximum load-slip of the curve segment of the nth load-slip curve; The step of calculating the absolute value of the difference between the second area and each first area includes: (9) in, represents the absolute value corresponding to the nth load-slip curve, represents the second area, Represents the first area corresponding to the nth load-slip curve.

[0012] In one embodiment, the calculating of the energy error based on each of the absolute values ​​includes: (10) Where E represents the energy error, It represents the absolute value corresponding to the nth load-slip curve, n represents the index of the load-slip curve, N represents the total number of load-slip curves, 1≤n≤N.

[0013] In one embodiment, the maximum shear load of the friction section is calculated based on the average value of the maximum shear loads of the friction section of all load-slip curves; the maximum load slip of the friction section is calculated based on the average value of the maximum load slips of the friction section of all load-slip curves; the shear stiffness of the friction section is calculated based on the maximum shear load and maximum load slip of the friction section.

[0014] In one embodiment, the maximum shear load of the slip segment is calculated based on the average value of the maximum shear loads of the slip segments of all load-slip curves; the maximum load slip of the slip segment is calculated based on the average value of the maximum load slips of the slip segments of all load-slip curves; the shear stiffness of the slip segment is calculated based on the maximum shear load and maximum load slip of the slip segment.

[0015] In one embodiment, for the curve segment, based on the curve fitting formula The corresponding load-slip curve is used to solve the shear stiffness, including: Dividing the curved line segment into a first broken line segment before the shear connector yields and a second broken line segment after the shear connector yields, wherein the slope of the first broken line segment is greater than the slope of the second broken line segment; Obtain a bilinear model of the first polyline segment and the second polyline segment; Based on the area equality principle of energy balance and the bilinear model, the bilinear model is calculated. Mathematically, the ordinate of the yield point and is the abscissa of the mathematical yield point; where, represents the shear stiffness of the shear connector before yielding, It represents the shear stiffness of the shear connector after yielding; Based on the Mathematically, the ordinate of the yield point and The abscissa and ordinate of the turning point between the first zigzag line segment and the second zigzag line segment are calculated based on the abscissa of the mathematical yield point; Based on the abscissa and ordinate of the turning point between the first fold line segment and the second fold line segment, the shear stiffness before yielding and the shear stiffness after yielding of the curved line segment are calculated.

[0016] In one embodiment, the step of obtaining the bilinear model of the first fold line segment and the second fold line segment includes: (11) in, represents the bilinear model for curve segment fitting, , , represents the slip when the shear connector yields, Represents the shear load when the shear connector yields.

[0017] In one embodiment, the area equality principle based on energy balance and the bilinear model are used to calculate the area Mathematically, the ordinate of the yield point and The abscissa of the mathematical yield point includes: (14) Among them, P A In the bilinear model, The ordinate of the mathematical yield point is In the bilinear model, The horizontal coordinate of the mathematical yield point.

[0018] In one embodiment, the Mathematically, the ordinate of the yield point and The abscissa and ordinate of the turning point between the first zigzag segment and the second zigzag segment are calculated by: (15) Among them, s y and P y The horizontal and vertical coordinates respectively represent the turning point between the first zigzag segment and the second zigzag segment.

[0019] In one embodiment, the calculation of the shear stiffness before yielding and the shear stiffness after yielding of the curved segment based on the abscissa and ordinate of the turning point between the first fold line segment and the second fold line segment includes: (16) in, represents the shear load variation of the fitting curve segment, represents the load-slip variation of the fitting curve segment, Represents the shape characteristic parameters of the fitting curve; , , .

[0020] The beneficial effects of the present invention are: Fitting curve parameters on the curve segment In the determination of The value reduces the dependence on experience and is more applicable. At the same time, it provides clear theoretical guidance from the energy perspective, points out a new direction for the corresponding research, and can also be used as a reference for determining the stiffness of other types of shear connectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a common form of shear connector schematic diagram; Figure 2 It is a common load-slip curve diagram of shear connectors; Figure 3 It is a schematic flow chart of a method for determining the shear stiffness of a bolt shear connector with a reserved hole according to an embodiment of the present application; Figure 4 It is a schematic diagram of three load-slip curves of a shear connector with bolts with reserved holes obtained based on three groups of test data in one embodiment of the present application; Figure 5 is a fitting curve parameter of an embodiment of the present application Schematic diagram of the determination method flow chart; Figure 6 It is a schematic flow chart of a method for determining shear stiffness of a curve segment based on energy balance according to an embodiment of the present application; Figure 7 It is a schematic diagram of a shear stiffness analysis model based on energy balance according to an embodiment of the present application.

[0022] In the figure, 01, shear connector; 02, concrete slab; 03, steel beam; 04, approximately linear elastic stage; 05, plastic stage; 06, descending stage. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0024] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0025] The serial numbers assigned to the components in this article, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning.

[0026] Based on the method for determining the shear stiffness of a bolt shear connector with a reserved hole applied by the present invention, please refer to Figure 3 ,include: Step S10, obtaining multiple load-slip curves of the shear connector with pre-reserved holes and bolts based on the test data.

[0027] Please refer to Figure 4 , the figure shows three load-slip curves of the shear connector with pre-reserved holes and bolts obtained based on three sets of test data. Those skilled in the art can understand that this is just a schematic, and in order to obtain more accurate results, this solution can be implemented based on more load-slip curves.

[0028] from Figure 4 It can be seen that the slip line of the bolted shear connector with reserved holes can be roughly divided into three sections. The first section is the friction force resisting the shear load, which is linear; the second section is the nearly horizontal horizontal line caused by slip after the friction force fails; the third section is the interaction between the bolt and the concrete to resist the shear load, which is curve-like and nonlinear.

[0029] Step S20, dividing each load-slip curve into a friction section, a sliding section and a curve section, and determining the shear stiffness of the friction section, the sliding section and the curve section respectively.

[0030] Among them, the friction section is formed by friction force resisting shear load and is linear; the slip section is composed of nearly horizontal horizontal lines produced by slip after the friction force fails; the curved section is formed by the interaction between bolts and concrete to resist shear load and is nonlinear.

[0031] For the friction section and the slip section, the specific value of the fitting curve can be determined directly by the average value of each load-slip curve in the friction section and the slip section. Therefore, in one embodiment, the maximum shear load for the friction section is calculated based on the average value of the maximum shear load of the friction section of all load-slip curves, which can be expressed as: (1) Among them, P l represents the maximum shear load in the friction section, n represents the index of the load-slip curve, P l,n represents the maximum shear load of the friction segment of the nth load-slip curve, N represents the total number of load-slip curves, 1≤n≤N.

[0032] Depend on Figure 4It can be seen that the maximum shear load of the friction section of the nth load-slip curve is the shear load at the end of the friction section of the nth load-slip curve. Therefore, the maximum shear load of the friction section is the shear load at the end of the friction section.

[0033] In one embodiment, the maximum load slip of the friction section is calculated based on the average value of the maximum load slip of the friction section of all load-slip curves, which can be expressed as: (2) Among them, s l represents the maximum load-slip in the friction section, n represents the index of the load-slip curve, s l,n It represents the maximum load slip of the friction section of the nth load-slip curve. N represents the total number of load-slip curves, 1≤n≤N.

[0034] Thus, the end point L (s l ,P l ).

[0035] Then the shear stiffness of the friction section can be calculated based on the maximum shear load and maximum load slip of the friction section, which can be expressed as: (3) in, Represents the shear stiffness of the friction segment.

[0036] In one embodiment, the maximum shear load of the slip segment is calculated based on the average value of the maximum shear loads of the slip segments of all load-slip curves and can be expressed as: (4) Among them, P h represents the maximum shear load of the slip segment, n represents the index of the load-slip curve, P h,n It represents the maximum shear load of the slip segment of the nth load-slip curve. N represents the total number of load-slip curves, 1≤n≤N.

[0037] Depend on Figure 4 It can be seen that the maximum shear load of the slip segment of the nth load-slip curve is the shear load at the end of the slip segment of the nth load-slip curve. Therefore, the maximum shear load of the slip segment is the shear load at the end of the slip segment.

[0038] In one embodiment, the maximum load slip of the slip segment is calculated based on the average value of the maximum load slip of the slip segment of all load-slip curves, which can be expressed as: (5) Among them, s hrepresents the maximum load slip of the slip segment, n represents the index of the load-slip curve, s h,n It represents the maximum load slip of the slip segment of the nth load-slip curve. N represents the total number of load-slip curves, 1≤n≤N.

[0039] Thus, the end point H (s h ,P h ).

[0040] Then the shear stiffness of the sliding section can be calculated based on the maximum shear load and maximum load slip of the sliding section, which can be expressed as: (6) in, Represents the shear stiffness of the slip segment.

[0041] For curve segments, based on the curve fitting formula The corresponding load-slip curve is used to solve the shear stiffness. q represents the shear load of the curve segment, P qu represents the maximum shear load of the curve segment, s represents the relative slip between the concrete slab and the steel beam, s h represents the relative slip corresponding to the end of the slip segment, represents the fitting curve parameter, and e represents the natural number base. This curve fitting formula is a classic curve fitting formula.

[0042] However, for the fitting curve parameters in the formula Currently, it is a value directly determined based on respective tests. The value determined by each test is different and cannot be applied to all situations. It is highly dependent on experience.

[0043] In view of this, the present application provides a fitting curve parameter A method for determining the energy balance of a It has a stronger value and is more applicable. It also provides theoretical guidance and points out a new direction for the corresponding research.

[0044] Please refer to Figure 5 In one embodiment, the fitting curve parameters Methods for determining include: Step S100: preset initial values ​​of fitting curve parameters .

[0045] Here, an initial value of the fitting curve parameter is assumed .

[0046] Step S200, calculating the average value of the maximum shear loads of all curve segments in the multiple load-slip curves, and taking the average value of the maximum shear loads as the curve segment maximum shear load P qu .

[0047] In one embodiment, step S200 may include: (7) Among them, P qu,n It represents the maximum shear load of the curve segment of the nth load-slip curve. N represents the total number of load-slip curves, 1≤n≤N.

[0048] Step S300, calculating the average value of the maximum slip of all curve segments in multiple load-slip curves, and taking the average value of the maximum slip as the curve segment maximum load slip s u .

[0049] In one embodiment, step S300 may include: (8) Among them, s u,n Represents the maximum load-slip of the curve segment of the nth load-slip curve.

[0050] Step S400, calculate the distance between each curve segment and the s-axis [s h,n ,s u,n ] segment as the first area. Where n represents the index of the load-slip curve.

[0051] For each load-slip curve, calculate the s on the s axis. h to u The area enclosed by the segment and the curve segment is taken as the corresponding first area.

[0052] Step S500, calculation formula The curve and the s-axis [s h ,s u ] segment is taken as the second area.

[0053] Hereinafter, steps S600 to S800 are implemented based on energy balance.

[0054] Step S600, calculating the absolute value of the difference between the second area and each first area.

[0055] In one embodiment, step S600 includes: (9) in, represents the absolute value corresponding to the nth load-slip curve, represents the second area, Represents the first area corresponding to the nth load-slip curve.

[0056] Step S700, calculating the energy error based on each absolute value.

[0057] In one embodiment, step S700 includes: (10) Where E represents the energy error, It represents the absolute value corresponding to the nth load-slip curve, n represents the index of the load-slip curve, N represents the total number of load-slip curves, 1≤n≤N.

[0058] Step S800, based on linear programming iterative solution, the energy error is minimized to obtain the initial value The solution is used as the fitting curve parameter The value of .

[0059] Based on steps S100 to S800, a general It has a stronger value and is more applicable. It also provides theoretical guidance and points out a new direction for the corresponding research.

[0060] The above is based on the determination The fitting formula of the value can be used to obtain a determined fitting curve. Based on the fitting curve, the shear stiffness can be determined by the existing technology. The embodiment of the present application provides a method for determining the shear stiffness based on energy balance. Please refer to Figure 6 ,include: Step S1000: dividing the curve segment into a first broken line segment before the shear connector yields and a second broken line segment after the shear connector yields, wherein the slope of the first broken line segment is greater than the slope of the second broken line segment.

[0061] Please refer to Figure 7 According to energy balance, the area enclosed by the first and second zigzag segments should be equal to , from a geometric point of view, there are countless possibilities for two broken lines that satisfy this relationship. Figure 7In the figure, the area of ​​triangle HCF is equal to the area enclosed by curve HF and straight line HF. As long as point C is located on AB parallel to HF, any movement of point C will satisfy the requirement of equal area. From a design perspective, point C cannot be too close to point A, because this will cause the stiffness before yielding to be too large and fail to truly reflect the load-slip response characteristics of the shear connector. Similarly, point C cannot be too close to point B, because if it is too close to point B, the shear stiffness after yielding will approach 0, which is inconsistent with the actual situation. Therefore, point C, the midpoint of AB, is taken as a compromise to ensure that the stiffness before yielding is not too large and the stiffness after yielding is not too small. Taking point C as the decomposition point, the HC segment is the first broken line segment and the CF segment is the second broken line segment. Let the position corresponding to point C on the s-axis be s y , then [s h ,s y ] The range can be regarded as the pre-yield stage of the shear connector, that is, the first broken line segment, with a larger slope, that is, a larger stiffness. [s y , s u ] range can be regarded as the post-yield stage of the shear connector, that is, the second broken line segment, with a smaller slope, that is, smaller stiffness.

[0062] Step S2000, obtaining a bilinear model of the first fold line segment and the second fold line segment.

[0063] Based on step S1000, the bilinear model of the first fold line segment and the second fold line segment can be expressed by formula (11), including: (11) in, represents a bilinear model for curve segment fitting; It indicates the shear stiffness of the shear connector before yielding, i.e. the shear stiffness in normal use (kN / mm). ; represents the shear stiffness of the shear connector after yielding (kN / mm), ; Indicates the slip when the shear connector yields (mm); It represents the shear load (kN) at which the shear connector yields.

[0064] Based on the above analysis of point C in the figure, to solve the position of point C, it is necessary to solve the positions of points A and B first.

[0065] Step S3000, based on the area equality principle of energy balance and the bilinear model, calculate the area of ​​the bilinear model. Mathematically, the ordinate of the yield point and The horizontal coordinate of the mathematical yield point.

[0066] Based on energy balance, the relationship of equal area can be expressed as: (12) in, Represents an idealized two-segment broken line bilinear model The area difference between the actual load-slip curve and the fitted one, represents the fitted actual load-slip curve.

[0067] The formula Substituting formula (11) into formula (12), we can get the calculation of the ordinate P of point A: A and the horizontal coordinate of point B Formula (13) can be expressed as: (13) Among them, P A In the bilinear model, The ordinate of the mathematical yield point is In the bilinear model, The horizontal coordinate of the mathematical yield point is Figure 7 In, A In the bilinear model, is the abscissa of the mathematical yield point, In the bilinear model, The ordinate of the mathematical yield point.

[0068] Then, according to formula (13), we can get P A and Solution: (14) Step S4000, based on the Mathematically, the ordinate of the yield point and The abscissa and ordinate of the turning point between the first broken line segment and the second broken line segment are calculated.

[0069] Taking full account of the change in stiffness before and after yielding, the compromise midpoint C is selected as the ideal turning point. y , P y ) can be deduced from the calculation result of equation (14): (15).

[0070] Step S5000, based on the abscissa and ordinate of the turning point between the first fold line segment and the second fold line segment, calculate the shear stiffness before yielding and the shear stiffness after yielding of the curve segment.

[0071] Based on formula (15), we have: (16) in, represents the shear load variation of the fitting curve segment, represents the load-slip variation of the fitting curve segment, Represents the shape characteristic parameters of the fitting curve; , , .

[0072] In this way, the shear stiffness of the shear connector with reserved holes and bolts at each stage was obtained.

[0073] In one embodiment of the present application, a computer-readable storage medium is provided, on which a program is stored. The stored program includes a method that can be loaded by a processor and process any of the above embodiments.

[0074] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

[0075] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A method for determining the shear stiffness of a bolt shear connector with a reserved hole, characterized in that: include: Based on the test data, multiple load-slip curves of bolted shear connectors with pre-reserved holes are obtained; Each load-slip curve is divided into friction section, sliding section and curve section, and the shear stiffness of the friction section, sliding section and curve section is determined respectively; the friction section is formed by friction force resisting shear load, which is linear; the sliding section is composed of nearly horizontal horizontal lines produced by sliding after the friction force fails; the curve section is formed by the interaction between bolts and concrete to resist shear load, which is nonlinear; For curve segments, based on the curve fitting formula The corresponding load-slip curve is used to solve the shear stiffness; where P q represents the shear load of the curve segment, P qu Indicates the maximum shear load of the curve segment, P h represents the shear load corresponding to the end of the slip segment, s represents the relative slip between the concrete slab and the steel beam, and s h represents the relative slip corresponding to the end of the slip segment, represents the fitting curve parameter, and e represents the natural number base; Among them, the fitting curve parameters Methods for determining include: Preset initial values ​​of fitting curve parameters ; Calculate the average value of the maximum shear loads of all curve segments in the multiple load-slip curves, and use the average value of the maximum shear loads as the curve segment maximum shear load P qu ; Calculate the average value of the maximum slip of all curve segments in the multiple load-slip curves, and use the average value of the maximum slip as the maximum load slip of the curve segment s u ; Calculate the distance between each curve segment and the s-axis [s h,n ,s u,n ] segment is taken as the first area, and n represents the index of the load-slip curve; Calculation formula The curve and the s-axis [s h ,s u ] is taken as the second area; calculating the absolute value of the difference between the second area and each first area; calculating an energy error based on each of the absolute values; Based on linear programming iterative solution, the energy error is minimized. The solution is used as the fitting curve parameter The value of .

2. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 1, characterized in that: The method further comprises calculating the average value of the maximum shear loads of all curve segments in the plurality of load-slip curves, and taking the average value of the maximum shear loads as the maximum shear load P of the curve segment. qu , include: （7） Among them, P qu,n represents the maximum shear load of the curve segment of the nth load-slip curve, N represents the total number of load-slip curves, 1≤n≤N; The calculation of the average value of the maximum slip of all curve segments in the plurality of load-slip curves is performed, and the average value of the maximum slip is used as the maximum load slip of the curve segment s u ,include: （8） Among them, s u,n represents the maximum load-slip of the curve segment of the nth load-slip curve; The step of calculating the absolute value of the difference between the second area and each first area includes: （9） in, represents the absolute value corresponding to the nth load-slip curve, represents the second area, Represents the first area corresponding to the nth load-slip curve.

3. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 1, characterized in that: The step of calculating the energy error based on each absolute value comprises: （10） Where E represents the energy error, It represents the absolute value corresponding to the nth load-slip curve, n represents the index of the load-slip curve, N represents the total number of load-slip curves, 1≤n≤N.

4. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 1, characterized in that: The maximum shear load of the friction section is calculated based on the average value of the maximum shear load of the friction section of all load-slip curves; the maximum load slip of the friction section is calculated based on the average value of the maximum load slip of the friction section of all load-slip curves; the shear stiffness of the friction section is calculated based on the maximum shear load and maximum load slip of the friction section.

5. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 1, characterized in that: The maximum shear load of the slip section is calculated based on the average value of the maximum shear loads of the slip sections of all load-slip curves; the maximum load slip of the slip section is calculated based on the average value of the maximum load slip of the slip sections of all load-slip curves; the shear stiffness of the slip section is calculated based on the maximum shear load and maximum load slip of the slip section.

6. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 1, characterized in that: For the curve segment, based on the curve fitting formula The corresponding load-slip curve is used to solve the shear stiffness, including: Dividing the curved line segment into a first broken line segment before the shear connector yields and a second broken line segment after the shear connector yields, wherein the slope of the first broken line segment is greater than the slope of the second broken line segment; Obtain a bilinear model of the first polyline segment and the second polyline segment; Based on the area equality principle of energy balance and the bilinear model, the bilinear model is calculated. Mathematically, the ordinate of the yield point and is the abscissa of the mathematical yield point; where, represents the shear stiffness of the shear connector before yielding, It represents the shear stiffness of the shear connector after yielding; Based on the Mathematically, the ordinate of the yield point and The abscissa and ordinate of the turning point between the first zigzag line segment and the second zigzag line segment are calculated based on the abscissa of the mathematical yield point; Based on the abscissa and ordinate of the turning point between the first fold line segment and the second fold line segment, the shear stiffness before yielding and the shear stiffness after yielding of the curved line segment are calculated.

7. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 6, characterized in that: The step of obtaining the bilinear model of the first fold line segment and the second fold line segment includes: （11） in, represents the bilinear model for curve segment fitting, , , represents the slip when the shear connector yields, Represents the shear load at which the shear connector yields.

8. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 7, characterized in that: The area equality principle based on energy balance and the bilinear model are used to calculate the area Mathematically, the ordinate of the yield point and The abscissa of the mathematical yield point includes: （14） Among them, P A In the bilinear model, The ordinate of the mathematical yield point is In the bilinear model, The horizontal coordinate of the mathematical yield point.

9. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 8, characterized in that: The above is based on the Mathematically, the ordinate of the yield point and The abscissa and ordinate of the turning point between the first zigzag segment and the second zigzag segment are calculated by: （15） Among them, s y and P y The horizontal and vertical coordinates respectively represent the turning point between the first zigzag segment and the second zigzag segment.

10. The method for determining the shear stiffness of a bolt shear connector with a reserved hole according to claim 9, characterized in that: The calculating of the shear stiffness before yielding and the shear stiffness after yielding of the curved segment based on the abscissa and ordinate of the turning point between the first fold line segment and the second fold line segment comprises: （16） in, represents the shear load variation of the fitting curve segment, represents the load-slip variation of the fitting curve segment, Represents the shape characteristic parameters of the fitting curve; , , .

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