A method for estimating the bearing capacity of a composite beam joint

Abstract

The present application relates to a kind of estimating method of composite beam node bearing capacity, belong to building reconstruction technical field, solve the problems of large calculation workload, low accuracy of existing bearing capacity estimation method.The composite beam node is used to overlap and connect the first beam body and the second beam body in composite beam, the node includes U-shaped connecting piece, the second beam body is fixedly connected to the open end of U-shaped connecting piece, and the first beam body is fixedly connected in the region surrounded by U-shaped connecting piece and second beam body;The equilibrium relationship of the second beam body lower surface force and bending moment is established based on the stress analysis of the U-shaped connecting piece, and the bearing capacity estimation model of U-shaped connecting piece is established according to the equilibrium relationship;And the bearing capacity estimation model of the mechanical anchor bolt in the composite beam node is established, and then the target bearing capacity estimation model is obtained;The ultimate bearing capacity of the composite beam node to be evaluated is estimated using the optimized target bearing capacity estimation model, which can simplify the bearing capacity calculation process and improve the bearing capacity estimation accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building reconstruction, and in particular to a method for estimating the bearing capacity of a composite beam joint. BACKGROUND

[0002] The composite beam joint is used for compositely connecting a first beam body and a second beam body in a composite beam, and comprises a U-shaped connecting piece, wherein the second beam body is located at an open end of the U-shaped connecting piece, and the first beam body is located in a region enclosed by the U-shaped connecting piece and the second beam body. The composite beam joint has twice shear connection, can realize complete transmission of shear force from the first beam body to the second beam body, and has good stability.

[0003] Since there is no such composite beam joint in the prior art, there is a lack of a corresponding bearing capacity estimation method. If the bearing capacity estimation method of other similar structures in the prior art is applied to the bearing capacity estimation method of the composite beam joint, one is a simplified method, which does not consider the contribution of the structural connecting anchor between the two beam bodies, completely determines the shear capacity of the single-section joint region according to the shear capacity of the transverse section of the U-shaped connecting piece, and considers a safety factor of no less than 1.5 times. The other is a finite element method, which uses a large general finite element software to calculate and model the single-section or multi-section joint region, and determines the shear capacity of the single-section joint region according to the finite element calculation and analysis results.

[0004] The above estimation methods at least have the following defects: first, the simplified method sets a safety factor that is obviously conservative based on the necessary safety reserve requirement of non-accurate estimation, which may lead to a failure to achieve optimal control effect of the civil engineering cost; second, the finite element method can accurately estimate the shear capacity level of the joint, but the joint modeling and calculation workload of the finite element method is large, which is not conducive to repetitive operation of multiple joints and multiple types, and the finite element method is limited by the software understanding, model checking and other related influencing factors of the modeling personnel, so that the accuracy of the calculation results cannot be fully guaranteed in the absence of third-party checking. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a method for estimating the bearing capacity of a composite beam joint, so as to solve the problem that there is a lack of effective bearing capacity calculation method for the composite beam joint in the prior art, and the problems of complex calculation, large calculation amount and low efficiency when the existing bearing capacity calculation method is used for the composite beam joint.

[0006] The present application provides a method for estimating the bearing capacity of a composite beam joint, the composite beam joint being used for compositely connecting a first beam body and a second beam body in a composite beam, and the joint comprising a U-shaped connecting piece, the second beam body being fixedly connected to an open end of the U-shaped connecting piece, and the first beam body being fixedly connected to a region enclosed by the U-shaped connecting piece and the second beam body;

[0007] Based on the stress analysis of the U-shaped connector, the equilibrium relationship between the force and bending moment on the lower surface of the second beam is established, and the bearing capacity estimation model of the U-shaped connector is established according to the equilibrium relationship; and the bearing capacity estimation model of the mechanical anchor bolt in the composite beam node is established, thereby obtaining the target bearing capacity estimation model;

[0008] The optimized target bearing capacity estimation model is used to estimate the ultimate bearing capacity of the composite beam joint to be evaluated.

[0009] Furthermore, it also includes: modifying the U-shaped connector bearing capacity estimation model by introducing the composite beam node structural influence coefficient and material influence coefficient, thereby obtaining an optimized U-shaped connector bearing capacity estimation model;

[0010] Furthermore, the establishment of the equilibrium relationship between the force and bending moment on the lower surface of the second beam based on the force analysis of the U-shaped connector includes:

[0011] According to the shear process, the first shear force V experienced by the U-shaped connector at the connection between the U-shaped connector and the upper flange of the second beam is... M The second shear force V experienced by the section where the bending moment is zero at the connection between the U-shaped connector and the first beam. V The vector sum is the ultimate bearing capacity V at the intersection of the U-shaped connector and the lower flange of the second beam, and the equilibrium relationship of the forces on the lower surface of the second beam is established.

[0012] V V =VV M ,

[0013] Among them, V M V represents the first shear force. V V represents the second shear force, and V represents the ultimate bearing capacity at the intersection of the U-shaped connector and the lower flange of the second beam.

[0014] According to the shear resistance process, at the section where the U-shaped connector intersects with the lower surface of the lower flange of the second beam, the vector sum of the first bending moment M1 generated by the connection between the U-shaped connector and the second beam and the third bending moment M3 generated by the eccentric tensile force is equal to the second shear force V at the section where the bending moment of the connection between the U-shaped connector and the first beam is zero. V Taking the second bending moment M2 corresponding to the moment of the lower flange of the second beam, the equilibrium relationship of the bending moment on the lower surface of the second beam is established:

[0015] M2 = M1 + M3,

[0016] M1 represents the first bending moment, M2 represents the second bending moment, and M3 represents the third bending moment.

[0017] Furthermore, the step of establishing a load-bearing capacity estimation model for the U-shaped connector based on this balance relationship includes:

[0018] The first bending moment, the second bending moment and the third bending moment are expressed in the form of resultant force, respectively as follows:

[0019]

[0020] wherein N represents the tension force borne by the section where the bending moment of the connecting part of the U-shaped connecting piece and the first beam body is zero; h b represents the height of the second beam body, h s represents the distance from the section where the bending moment of the connecting part of the U-shaped connecting piece and the first beam body is zero to the lower surface of the second beam body, i.e. the first distance; kb represents the eccentricity of the tension force, b represents the width of the connecting part of the U-shaped connecting piece and the second beam body, i.e. the width of the U-shaped connecting piece, and k represents the parameter to be calibrated;

[0021] The U-shaped connecting piece bearing capacity estimation model is established in combination with the balance relationship as follows:

[0022]

[0023] wherein A S = tb represents the sectional area of the U-shaped connecting piece, t represents the thickness of the U-shaped connecting piece, b represents the width of the U-shaped connecting piece, and f y represents the yield strength value of the U-shaped connecting piece,

[0024] Further, the method further comprises: calibrating the parameters in the U-shaped connecting piece bearing capacity estimation model by using a numerical simulation method.

[0025] The first distance is calibrated.

[0026] The shear force borne by the section where the bending moment of the connecting part of the U-shaped connecting piece and the first beam body is zero is used to take the moment on the bottom surface of the first beam body.

[0027]

[0028] M’ represents the fourth bending moment obtained after taking the moment, n represents the number of rows of the counter-pull bolt rods arranged on the U-shaped connecting piece, i represents the i-th row of counter-pull bolt rods arranged at intervals from the opening end to the bottom of the U-shaped connecting piece, h represents the distance from the section where the fourth bending moment is zero to the first row of counter-pull bolt rods, h i represents the distance from the i-th row of counter-pull bolt rods to the bottom surface of the first beam body, F i represents the shear force borne by the i-th row of counter-pull bolt rods, and β represents the bearing capacity coefficient.

[0029] The influence definition function is characterized by a fourth bending moment and a bending moment obtained by taking a moment on the bottom surface of the first beam body with respect to the shear force of each row of the pair of pull-rod bars, and the influence definition function is an influence function of constraint effect and bending effect of the bottom surface of the first beam body on redistribution of internal force thereof:

[0030]

[0031] wherein, the influence definition function is F i = m i × V V , Let and the influence definition function can be obtained after transformation as follows:

[0032]

[0033] The first distance h s is determined according to the transformed influence definition function by the following formula:

[0034]

[0035] wherein, H b represents the height of the first beam body.

[0036] Further, the U-shaped connecting piece bearing capacity estimation model is modified by introducing a composite beam node structure influence coefficient, comprising:

[0037] The thickness-width ratio of the U-shaped connecting piece is introduced to modify the first distance h s :

[0038]

[0039]

[0040] wherein, t represents the thickness of the U-shaped connecting piece, b represents the width of the U-shaped connecting piece, and a b represents the bending deformation coefficient of the U-shaped connecting piece.

[0041] Further, the U-shaped connecting piece bearing capacity estimation model is modified by introducing a composite beam node structure influence coefficient, further comprising:

[0042] The width-height ratio of the U-shaped connecting piece is introduced to modify the first distance h s :

[0043]

[0044]

[0045] wherein, β b represents the width-height ratio influence coefficient of the U-shaped connector, H s represents the nominal distance from the first row of the pair of pull rod to the lower surface of the second beam body when the spacing of each row of the pair of pull rod changes.

[0046] Further, the modification of the bearing capacity estimation model of the U-shaped connector by introducing the composite beam node structure influence coefficient further comprises:

[0047] The modification of the bearing capacity estimation model of the U-shaped connector by introducing the composite beam node material quality influence coefficient comprises:

[0048] The first distance h s is modified by introducing the material quality influence coefficient of the U-shaped connector:

[0049]

[0050]

[0051] wherein, ζ b represents the material quality influence coefficient, E s represents the elastic modulus of the U-shaped connector.

[0052] Further, the modification of the bearing capacity estimation model of the U-shaped connector by introducing the composite beam node structure influence coefficient further comprises:

[0053] The first distance h s is modified by introducing the influence coefficient of the number of rows of the pair of pull rod:

[0054]

[0055] When each row of the pair of pull rod is arranged at equal intervals,

[0056] When each row of the pair of pull rod is arranged at unequal intervals,

[0057] wherein, H' S represents the distance from the first row of the pair of pull rod to the lower surface of the second beam body, λ b represents the influence coefficient of the number of rows of the pair of pull rod.

[0058] Further, the mechanical anchor bolt fixedly connects the top end of the first beam body and the bottom end of the second beam body.

[0059] The bearing capacity estimation model of the mechanical anchor bolt in the composite beam node is:

[0060] V 机械锚栓 = α s fys A ss ,

[0061] Wherein, f ys Mechanical anchor yield strength, A ss Mechanical anchor effective stress section area, alpha s Mechanical anchor bearing capacity coefficient.

[0062] Further, the target bearing capacity model is:

[0063]

[0064] Wherein, n1 indicates the number of U-shaped connectors in the composite beam joint, and n2 indicates the number of mechanical anchors in the composite beam joint.

[0065] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0066] 1. The composite beam joint bearing capacity estimation method provided by the present application, by force analysis of the composite beam joint, the balance relationship between force and bending moment is established, and then the bearing capacity calculation model of the U-shaped connector is obtained, and the bearing capacity calculation model of the mechanical anchor in the composite beam joint is established, based on the above two bearing capacity calculation models, the known parameters of the composite beam joint can be directly input to quickly estimate the ultimate bearing capacity of the composite beam joint, the calculation is simple, the calculation amount is small, and the efficiency is high, which is convenient for efficient use in actual building engineering.

[0067] 2. The composite beam joint bearing capacity estimation method provided by the present application, by calibrating the parameters in the bearing capacity calculation model of the U-shaped connector, and introducing the thickness-width ratio influence coefficient of the U-shaped connector, the width-height ratio influence coefficient, the row number influence coefficient of the tension bolt, and the material quality influence coefficient to optimize the estimation model, a high-precision estimation model is obtained, the calculation precision of the joint shear bearing capacity is effectively improved, and the cost control level of the joint engineering application is fully improved.

[0068] In the present application, the above technical solutions can be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0069] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the description. It shall be apparent that the accompanying drawings should be only used to illustrate the specific embodiments and should not be considered as limiting the present application. In the entire drawings, the same reference numerals indicate the same or similar components.

[0070] Figure 1A structural schematic diagram of the composite beam joint provided by the embodiment of the present application;

[0071] Figure 2 A structural schematic diagram of the composite beam joint connecting the first beam body and the second beam body in the embodiment of the present application;

[0072] Figure 3 A flowchart of the bearing capacity estimation method of the composite beam joint in the embodiment of the present application;

[0073] Figure 4 A schematic diagram of the upper force relationship of the composite beam joint in the embodiment of the present application;

[0074] Figure 5 A schematic diagram of the transverse shear force distribution of the U-shaped connecting piece and the binding part of the steel beam in the embodiment of the present application;

[0075] Figure 6 A schematic diagram of the longitudinal shear stress distribution of the U-shaped connecting piece and the binding part of the steel beam in the embodiment of the present application;

[0076] Figure 7 A schematic diagram of the stress distribution of the U-shaped connecting piece and the binding part of the steel beam in the embodiment of the present application after simplification;

[0077] Figure 8 A schematic diagram of the stress distribution of the U-shaped connecting piece when the edge thereof just yields in the embodiment of the present application;

[0078] Figure 9 A schematic diagram of the stress distribution of the U-shaped connecting piece when the cross section thereof is fully yielded in the embodiment of the present application;

[0079] Figure 10 A schematic diagram of the stress distribution when 1-4 rows of the opposite-pull bolt rods are arranged in the embodiment of the present application;

[0080] Figure 11 A schematic diagram of the stress distribution when 5-7 rows of the opposite-pull bolt rods are arranged in the embodiment of the present application;

[0081] Figure 12 A schematic diagram of the stress distribution of the U-shaped connecting piece and the bolt hole when 4 rows of the opposite-pull bolt rods are arranged in the embodiment of the present application;

[0082] Figure 13 A schematic diagram of the stress distribution and size relationship of the U-shaped connecting piece and the bolt hole when 4 rows of the opposite-pull bolt rods are arranged in the embodiment of the present application;

[0083] Figure 14 A schematic diagram of the fitting result between the width-height ratio of the U-shaped connecting piece and the influence definition function in the embodiment of the present application;

[0084] Figure 15 A schematic diagram of the fitting result between the width-height ratio of the U-shaped connecting piece and the influence definition function a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function;

[0085] Figure 16 a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function; a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function;

[0086] Figure 17 a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function; a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function;

[0087] Figure 18 a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function; a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function;

[0088] Figure 19 a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function; a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function;

[0089] Figure 20 a schematic diagram of the fitting result between the U-shaped connecting piece width-height ratio and the influence definition function.

[0090] Reference signs:

[0091] 1-first beam body; 2-second beam body; 21-upper flange; 22-lower flange; 23-web; 24-stiffening rib; 3-U-shaped connecting piece; 4-mechanical anchor bolt; 5-node structure anchor bolt; 6-pull bolt. DETAILED DESCRIPTION

[0092] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application. The drawings show, by way of illustration, the principles of the application and the preferred embodiments to convey the substance of the application to those skilled in the art. It is to be understood that other embodiments can be utilized and that structural and functional changes can be made without departing from the scope of the present application.

[0093] In order to better illustrate the estimation method of the composite beam node bearing capacity proposed in the present application, the composite beam node in the present application will be described. Exemplarily, in actual engineering construction, some buildings with historical and cultural significance usually do not change their original structure and appearance when they are repaired, but support and stabilize the old structure by building new structures. In order to strengthen the stabilizing effect of the new structure on the old structure, a composite beam node is introduced to connect and fix the new structure and the old structure. Specifically, the composite beam node is used to connect the first beam body 1 and the second beam body 2 in the composite beam, and its specific structure is as shown in Figure 1 Figure 2 ​As shown, including U-shaped connecting piece 3, mechanical anchor bolt 4, node structure anchor bolt 5 and post-tensioning bolt 6, the second beam body 2 is located at the open end of the U-shaped connecting piece 3, the first beam body 1 is located in the area surrounded by the U-shaped connecting piece 3 and the second beam body 2, the bottom end of the first beam body 1 is connected with the bottom end of the U-shaped connecting piece 3 through the node structure anchor bolt 5, and the top end of the first beam body 1 is connected with the bottom end of the second beam body 2 through the mechanical bolt 4; the post-tensioning bolt 6 penetrates the U-shaped connecting piece 3 and the first beam body 1. Among them, the side wall of the U-shaped connecting piece 3 extends to the top end of the second beam body 2, and is fixedly connected (for example, welded) with the top end and / or side wall of the second beam body 2.

[0094] In one specific embodiment of the present application, a method for estimating the bearing capacity of a composite beam node is disclosed. Figure 3 As shown:

[0095] S110, a balance relationship between the force and the bending moment of the lower surface of the second beam body is established based on the stress analysis of the U-shaped connecting piece, and a U-shaped connecting piece bearing capacity estimation model is established according to the balance relationship.

[0096] S120, and a bearing capacity estimation model of the mechanical anchor bolt in the composite beam node is established, and then a target bearing capacity estimation model is obtained.

[0097] S130, the optimized target bearing capacity estimation model is used to estimate the ultimate bearing capacity of the composite beam node to be evaluated.

[0098] Preferably, in order to improve the calculation accuracy of the model, the above method further comprises: introducing a composite beam node structure influence coefficient and a material quality influence coefficient to modify the U-shaped connecting piece bearing capacity estimation model to obtain an optimized U-shaped connecting piece bearing capacity estimation model.

[0099] Preferably, the balance relationship between the force and the bending moment of the lower surface of the second beam body based on the stress analysis of the U-shaped connecting piece comprises:

[0100] Exemplarily, the U-shaped connecting piece is a U-shaped shear plate, the first beam body is a concrete beam, and the second beam body is a steel beam. In the process of finite element numerical analysis, the upper flange 21, the lower flange 22 and the stiffening rib 24 of the U-shaped connecting piece and the steel beam are bound and constrained, and the stress analysis of the shear plate is performed as shown in Figure 4 It can be found that: the shear plate bound with the steel beam will generate a part of force V M , and the shear plate anchored with the concrete beam will generate a part of force V V , and the two together constitute the ultimate bearing capacity V of the position where the lower flange of the steel beam intersects with the U-shaped connecting piece in the shear process of the U-shaped connecting piece, and the bearing capacity of the U-shaped connecting piece is V V = V-V M .

[0101] The transverse and longitudinal shear stress distribution of the binding part of the U-shaped connecting piece and the steel beam is shown in Figure 5 , Figure 6 The meanings of the parameters in the figure are as follows:

[0102] t1 represents the thickness of the lower flange of the steel beam, t2 represents the thickness of the web of the steel beam, t3 represents the thickness of the upper flange of the steel beam, τ x1 represents the transverse shear stress distribution of the binding part of the U-shaped hoop and the lower flange of the steel beam, τ x2 represents the transverse shear stress distribution of the binding part of the U-shaped hoop and the web of the steel beam, τ x3 represents the transverse shear stress distribution of the binding part of the U-shaped hoop and the upper flange of the steel beam, τ y1 represents the longitudinal shear stress distribution of the binding part of the U-shaped hoop and the lower flange of the steel beam, τ y2 represents the longitudinal shear stress distribution of the binding part of the U-shaped hoop and the web of the steel beam, τ y3 represents the longitudinal shear stress distribution of the binding part of the U-shaped hoop and the upper flange of the steel beam.

[0103] According to the shear process, the vector sum of the first shear force V M exerted on the connecting part of the U-shaped connecting piece and the upper flange of the second beam body and the second shear force V V exerted on the section where the bending moment of the connecting part of the U-shaped connecting piece and the first beam body is zero is the ultimate bearing capacity V at the position where the U-shaped connecting piece intersects with the lower flange of the second beam body, and a balance relationship of the force on the lower surface of the second beam body is established;

[0104] V V = V-V M ,

[0105] wherein V M represents the first shear force, V V represents the second shear force, and V represents the ultimate bearing capacity at the position where the U-shaped connecting piece intersects with the lower flange of the second beam body.

[0106] According to the shear process, the vector sum of the first bending moment M1 generated by the connecting part of the U-shaped connecting piece and the second beam body at the section where the U-shaped connecting piece intersects with the lower flange of the second beam body and the third bending moment M3 generated by the eccentric action of the tension force is the second shear force V V exerted on the section where the bending moment of the connecting part of the U-shaped connecting piece and the first beam body is zero, and a balance relationship of the bending moment on the lower surface of the second beam body is established by taking the moment corresponding to the second bending moment M2:

[0107] M2 = M1 + M3,

[0108] M1 represents the first bending moment, M2 represents the second bending moment, and M3 represents the third bending moment. Specifically, the eccentric action of the tension force is the tension force generated by the relative horizontal slip of the first beam body and the second beam body.

[0109] That is, the second beam body lower surface force and bending moment balance relationship is:

[0110] V V = V-V M , M2 = M1 + M3 (1)

[0111] The force, bending moment component is expressed by integral as follows:

[0112]

[0113] Wherein, τ represents the U-shaped shear plate on the main force part of the bending moment of the section is zero shear stress, A s represents the U-shaped connecting piece section area, that is, the shear plate section area, A sm represents the U-shaped connecting piece and steel beam binding part of the section area, wherein, x represents the length of the force arm of the transverse shear force, y represents the length of the force arm of the longitudinal shear force.

[0114] Because the cross-sectional area is obtained by integration of the form of the cross-sectional force, the force of the U-shaped connecting piece and the steel beam connecting part is further simplified to the form of concentrated force, and the tension will produce a certain eccentric effect in the process of stress. In order to realize the correction of the force arm, the tension eccentricity is defined as kb. Wherein k is a to-be-determined coefficient, which is defined as the tension eccentricity coefficient.

[0115] Specifically, after simplification to the form of concentrated force, the force of the U-shaped connecting piece and the steel beam connecting part is as shown in Figure 7 , wherein, V M’ represents the sum of the shear force of the web 23, h b’ represents the distance from V M’ to the lower surface of the steel beam, t' represents the distance from V to the lower surface of the steel beam.

[0116] Specifically, let t2 = t3 = t b , wherein, t b represents the thickness value when the upper flange, lower flange and the like are equal in thickness. Because the web has small transverse stiffness relative to the flange, the shear force V M’ it bears is relatively small, and formula (1) can still be effectively established. The bending moment is expressed by the form of resultant force as follows:

[0117]

[0118] Wherein, N represents the tension of the section of the U-shaped connecting piece and the first beam body connecting part with zero bending moment; h b represents the height of the second beam body, h sThe first distance is the distance from the section where the U-shaped connector and the first beam body connecting part bending moment is zero to the second beam body lower surface, that is, the first distance; kb represents the tension eccentricity, b represents the width of the U-shaped connector and the second beam body connecting part, that is, the width of the U-shaped connector, and k represents the to-be-calibrated parameter.

[0119] Because t b , t' is relatively small h b , V M’ is relatively small V M , the influence on the result is not great, for the convenience of later calculation, M1 is calculated according to the following formula in this paper:

[0120] M1 = V M × h b (1)

[0121] The first bending moment, the second bending moment and the third bending moment are expressed in the form of resultant force, respectively:

[0122]

[0123] Considering the above conditions, the force and bending moment balance relationship is determined as follows:

[0124]

[0125] The values of M1 and M2 are not equal, and the bending moment M3 will be generated under the eccentric action of the section tension to ensure the balance of the force system at the same section. In this application, M3 = Nkb is used to realize the balance of the section force system, thereby verifying the correctness of the established formula (5) force and bending moment balance relationship.

[0126] The formula (5) is deformed to eliminate V M , and the specific is:

[0127]

[0128]

[0129] Definition:

[0130] N = β1V V (5)

[0131] V V = β2f y A s (6)

[0132] Then the formula (7) is changed to:

[0133]

[0134] Since N and V V The ratio β1 and Correlation, β1 and h s Positive correlation, β1 and b inverse correlation. But because the invention h s The range below the part and its different, so define β3' reflects the relationship between the two values:

[0135]

[0136] To establish V V And f y A s The relationship, the bending stress generated under the action of V V And f y Establish the corresponding relationship, determine the corresponding coefficient.

[0137] The bending stress σ' generated under the action of shear force and f y The ratio is α':

[0138]

[0139] Where W is the modulus of section,

[0140] When the section does not enter the plastic, α' ≤ 1, when the section enters the plastic, α' ≥ 1.

[0141] It is deformed as:

[0142]

[0143] Let:

[0144]

[0145] Then:

[0146]

[0147] The above two-step analysis establishes the relationship between β1, β2 and b, h s , respectively, further eliminates the effect of variables, and the final relationship is shown in the following formula:

[0148]

[0149] Substitute β1, β2 in equation (16) into equation (10):

[0150]

[0151] Where, A S= tb, represents the cross-sectional area of the U-shaped connector, t represents the thickness of the U-shaped connector, b represents the width of the U-shaped connector, f y represents the yield strength value of the U-shaped connector,

[0152] The stress conditions of the U-shaped connector edge just yielding and the U-shaped connector section fully yielding under the action of the bending moment are analyzed, respectively as shown in Figure 8 、 Figure 9 The bending moment size of the U-shaped connector edge just yielding is M a The bending moment size of the U-shaped connector section fully yielding is M b , Then:

[0153]

[0154]

[0155]

[0156] Then, other parameters in formula (17) are calculated and calibrated. Specifically, numerical simulation results are used for calibration. Exemplarily, the steel beam height is 500 mm, the concrete beam height is 900 mm, the tension bolt rod is arranged at an interval of 180 mm for 4, the tension bolt rod diameter is 20 mm (8.8 level), the U-shaped connector width is 200 mm, and it should be noted that the U-shaped connector width refers to the width of the sheet shear plate constituting the U-shaped connector.

[0157] The component values of the U-shaped connector thickness change are shown in Table 1 respectively:

[0158] Table 1

[0159]

[0160] The calibration of parameters k, a” and β’3 when the U-shaped connector thickness changes is shown in Table 2:

[0161] Table 2

[0162]

[0163] The ultimate bearing capacity of the U-shaped connecting piece is calculated when the width of the U-shaped connecting piece is 200mm, the height of the steel beam is 500mm, the height of the concrete beam is 900mm, and the distance between the pull bolts is 180mm, and the thickness of the U-shaped connecting piece is 4mm, 5mm, 6mm, 7mm and 8mm respectively. The specific parameters are calculated, and it can be obtained that α" can be taken as a constant 0.25 for this type, then α'=1.5, which is consistent with the calculation result of formula (18), β'3 can be taken as a constant 0.6 for 200mm width, and analysis can obtain that it is a value related to width, which can be taken as a constant under the same width, and the product of kβ'3 is a proper consideration of the influence of tension on the ultimate bearing capacity of the U-shaped connecting piece, which reflects the proportion of the bending moment generated by tension in the overall bending moment, and its influence is relatively small for this model. Considering the case of large width, each form is safe, and kβ'3 is taken as a constant 0.2. Calculation and analysis can obtain that it can meet the requirements when the width of the U-shaped connecting piece, the steel grade, the height of the concrete beam, the arrangement of the pull bolts and the height of the steel beam are changed. Substituting formula (17) into formula (17) obtains the following formula:

[0164]

[0165] Based on this, only one unknown quantity h s is contained in the above formula s .

[0166] The parameters in the bearing capacity estimation model of the U-shaped connecting piece are calibrated by using the numerical simulation method, that is, the first distance h s is calibrated.

[0167] Specifically, the arrangement of the pull bolts has a great influence on the ultimate bearing capacity of the U-shaped connecting piece, and α" can be taken as a constant 0.25 for this type, so the arrangement of the pull bolts mainly affects the value of h s , and the influence of the arrangement of the pull bolts and the height of the concrete beam should be fully considered in the establishment of h s .

[0168] The bearing capacity of the bolt hole is analyzed under different arrangement numbers of the pull bolts when the width of the U-shaped connecting piece is 200mm and the thickness is 6mm, as shown in Figure 10 , 11 When 1-5 rows of pull bolts are arranged, the shear force borne by the main stress bolt hole at the limit state is proportional to the distance from the concrete beam bottom surface, and when more than 5 rows of pull bolts are arranged, the stress condition is consistent with that of 5 rows of pull bolts.

[0169] The stress and size relationship of the U-shaped connecting piece and the bolt hole when 4 rows of pull bolts are arranged is as shown in Figure 12 , 13The application is illustrated by taking the introduction and calibration of specific coefficients in the case of arranging 4 rows of studs, and verifying the applicability of the target bearing capacity prediction model in the case of arranging 1, 2, 3 and 5 rows of studs. Figure 12 , 13 In the formula, d represents the arrangement distance of mechanical anchors, H b represents the height of the concrete beam, H S represents the distance from the first row of opposite-stud bars to the lower surface of the steel beam, H S represents the distance between the first row of opposite-stud bars and the second row of opposite-stud bars, h represents the distance from the section with zero bending moment to the first row of studs, and l represents the total length of the 3-unit model.

[0170] It can be found from the above Figure 12 that, due to the constraint effect of the bottom of the U-shaped connecting piece and the bending deformation in the shear process, the internal force is redistributed to a certain extent, and therefore, the moment taken on the bottom surface of the concrete beam by V V , βF1, βF2, βF3, βF4 is not zero. In order to determine the first distance h s , and realize unified analysis under different numbers of stud arrangements, the application adopts the method of taking moment on the bottom surface of the concrete beam by the section with zero bending moment at the upper end of the shear plate (U-shaped connecting piece) to calibrate h s , so as to fully consider the influence of the opposite-stud bar arrangement mode and the height of the concrete beam, wherein the sizes of F1, F2, F3 and F4 are considered to be proportional to the distance from the bottom surface of the concrete beam. Figure 13

[0171] The shear force on the section with zero bending moment at the upper end of the U-shaped connecting piece is taken on the bottom surface of the first beam body:

[0172]

[0173] M' represents the fourth bending moment obtained after taking moment, n represents the number of rows of opposite-stud bars arranged on the U-shaped connecting piece, i represents the i-th row of opposite-stud bars arranged at intervals from the opening end to the bottom of the U-shaped connecting piece, h represents the distance from the section with zero fourth bending moment to the first row of opposite-stud bars, h i represents the distance from the i-th row of opposite-stud bars to the bottom surface of the first beam body, F i represents the shear force on the i-th row of opposite-stud bars, and β represents the bearing capacity coefficient.

[0174] The bending moment obtained after taking moment on the bottom surface of the first beam body by the fourth bending moment and the shear force on each row of opposite-stud bars is used to characterize the influence definition function, which is the influence function of the constraint effect and bending effect of the bottom surface of the first beam body on the redistribution of the internal force thereof.​

[0175]

[0176] For ease of subsequent calculations, let but:

[0177]

[0178] in, Indicates the influence on the defined function, F i =m i ×V V , After transforming the function defining the influence, we can obtain:

[0179]

[0180] The first distance h is determined using the following formula based on the transformed effect definition function. s :

[0181]

[0182] Among them, H b This indicates the height of the first beam. In this embodiment, it is determined... The specific form of the function can accurately determine the ultimate bearing capacity of the U-shaped connector.

[0183] Preferably, the correction of the bearing capacity estimation model of the U-shaped connector by introducing the influence coefficient of the composite beam node structure includes:

[0184] First, the aspect ratio of the U-shaped connector is introduced to the first distance h. s Make corrections.

[0185] Specifically, in existing technologies, the design of anchor plates considers the influence of plate bending effects, which to some extent reflects the impact of the thickness-to-width ratio on bending. Considering that the coefficient should be dimensionless (1), the influence of the thickness-to-width ratio on bending deformation is introduced by α. b .

[0186] When the width of the U-shaped connector is 200mm, different thickness-to-width ratios can be used. draw and The relationship between them was determined and fitted accordingly, and the fitting result is as follows: Figure 14 As shown, this means that while keeping other variables constant, and There is a linear correlation between them. In this embodiment, the aspect ratio of the U-shaped connector is introduced to affect the first distance h. s After making corrections, the first distance h is obtained. s for:

[0187]

[0188]

[0189] where t represents the thickness of the U-shaped connector, b represents the width of the U-shaped connector, and a represents the bending deformation coefficient of the U-shaped connector. b where t represents the thickness of the U-shaped connector, b represents the width of the U-shaped connector, and a represents the bending deformation coefficient of the U-shaped connector.

[0190] h s The size of the U-shaped connector increases with the increase of the thickness, and the bending deformation during the deformation causes the redistribution of the internal force, and introduces the bending deformation coefficient a b When the width of the U-shaped connector is constant, the thickness is changed, and the coefficient is calibrated, a' = 1.5, b' = -3.2.

[0191] Secondly, the width-height ratio of the U-shaped connector is introduced to correct the first distance h s . Specifically, to further verify the correctness of the bearing capacity estimation model when the width changes, when the thickness of the U-shaped connector is 6nm, the height of the concrete beam is 900nm, and the height of the steel beam is 500nm, the corresponding bearing capacity when the width changes is analyzed, as shown in Table 3 below, and the width-height ratio influence coefficient β b is introduced to determine the parameters.

[0192] Table 3

[0193]

[0194] When only considering a b , the shear capacity is verified, as shown in Table 4.

[0195] Table 4

[0196]

[0197] From the calculation results in Table 4, when only considering the coefficient a b , the theoretical calculation value cannot be effectively controlled when the width changes. Under the premise of keeping the calculation result of a b unchanged, the U-shaped connector width influence coefficient β b is introduced, and the coefficient is dimensionless. The main reflection of the U-shaped connector width-height ratio is considered. Specifically, the relationship between a and b is drawn and fitted, and the fitting result is shown in Figure 15 . From the figure, it can be seen that a and b There is a linear relationship between them. In this embodiment, the aspect ratio of the U-shaped connector is introduced to correlate with the first distance h. s After making corrections, the first distance h is obtained. s for:

[0198]

[0199]

[0200] Where, β b H” represents the aspect ratio influence coefficient of the U-shaped connector. s This represents the nominal distance from the first row of tie rods to the lower surface of the second beam when the spacing of the tie rods in each row changes. Preferably, in Figure 13 In the middle, when H” S ≤H S When calculating β b At that time, H” S Let H' be the value of H' S When H” S >H S When calculating β b At that time, H” S Take as The coefficients are calibrated by utilizing the width variation of the U-shaped connector, where a” = 1.26 and b” = -0.23.

[0201] Preferably, α is considered under different width variations of the U-shaped connector. b β b The load-bearing capacity of the U-shaped connector was verified, as shown in Table 5.

[0202] Table 5

[0203]

[0204] Specifically, H” S When β changes, b A correctness analysis was conducted.

[0205] In practical applications, the height of concrete beams may vary. To further ensure the applicability of the established model when the concrete beam height changes, load-bearing capacity analysis is performed on models with different concrete beam heights. Load-bearing capacity calculations are performed when 3 or 4 tie rods are evenly spaced at intervals of 150mm, 160mm, 170mm, and 180mm, and the shear plate (U-shaped connector) is 200mm wide and 6mm thick. (Drawing...) and The relationship between them, specifically as follows: Figure 16 As shown in the figure. It can be seen from the figure that b remains constant, and H” S When changing, With a linear relationship between them.

[0206] In the embodiments of the present application, the case of arranging three rows of pull bolt rods at equal intervals is determined With a linear relationship between them, as shown in Figure 17 , thereby ensuring the applicability of the bearing capacity estimation model.

[0207] It can be known from Figure 17 that, under the condition of keeping other parameters unchanged, and are linearly related, which also verifies the correctness of taking b as .

[0208] Thirdly, the material quality influence coefficient of the U-shaped connecting piece is introduced to correct the first distance h s .

[0209] Preferably, the relationship between f y and is drawn and corresponding fitting is performed, and the fitting result is shown in Figure 18 . It can be known from Figure 18 that f y and still satisfy a linear correlation relationship, and through the shear bearing capacity analysis under different steel grades (i.e. material quality), it is found that under different material qualities, α” can still be taken as a constant 0.25, and the product of kβ’3 can still be taken as a constant 0.2, but it will affect the specific value of h s . Under the condition of keeping α b and β b unchanged, the material quality influence coefficient ζ b is introduced in the embodiments of the present application to realize effective control on the bearing capacity of the U-shaped hoop:

[0210]

[0211]

[0212] wherein ζ b represents the material quality influence coefficient, and the dimension is 1, E s represents the elastic modulus of the U-shaped connecting piece, and E S = 2.06 x 10 5 N / mm 2 . Through calculation, a”’ = 1.06 and b”’ = -38.

[0213] Fourthly, the influence coefficient of the row number of the pull bolt rod is introduced to correct the first distance h s .

[0214] Preferably, the influence of the different arrangement of the number of rows of the pair of studs on the ultimate bearing capacity of the U-shaped connector is ensured to be invariable. The β b H" S , which also reflects the arrangement of the number of rows of the pair of studs to some extent, keeps other variables unchanged, and the relationship between the different number of rows of the pair of studs n and is drawn and analyzed accordingly, as shown in Figure 19 From Figure 19 , it can be seen that n and are inversely related, which further reflects the influence of the ratio of H' S to h1 on the value of , under the condition of ensuring that the established α b , β b , ζ b are invariable, the arrangement mode influence coefficient λ b of the pair of studs is introduced, and the first distance h s is corrected as follows:

[0215]

[0216] When the pair of studs in each row are arranged at equal intervals,

[0217] When the pair of studs in each row are arranged at unequal intervals,

[0218] wherein H' S represents the distance from the first row of the pair of studs to the lower surface of the second beam body, and λ b represents the arrangement row influence coefficient of the pair of studs. Wherein, a”” = 1.1 and b”” = -0.43 are determined by calculation.

[0219] Thus, the bearing capacity estimation model of the U-shaped connector is obtained as follows:

[0220]

[0221] Since the contribution of the U-shaped connector to the shear bearing capacity of the middle unit is V V , for the arrangement of four studs, it is calculated as follows:

[0222]

[0223] Wherein α b , β b , ζ b , λ b are calculated according to formula (37).

[0224] For the arrangement of the pulling bolt rod with less than 3 rows, the bearing capacity cannot be fully exerted, so the number of rows of the pulling bolt rod should be ensured to be not less than 3, and the spacing should be not greater than 200 mm. For the equal spacing arrangement, the sizes of F1, F2, F3 and F4 are proportional to the distances from the pulling bolt rod to the bottom surface of the concrete beam, and the sizes of m1, m2, m3 and m4 are proportional to the distances from the pulling bolt rod to the bottom surface of the concrete beam, and the sum of the four is 1. For the arrangement of more than 5, because the stress of the pulling bolt rod is consistent with the arrangement of 5, and the influence on the ultimate bearing capacity is not large, the model can still be considered as Figure 13 The model is still applicable to the arrangement of 3 and 5 rows of pulling bolt rods.

[0225] For the arrangement of the pulling bolt rod with little difference in spacing, because the ultimate bearing capacity of the shear plate has little difference, the sizes of m1, m2, m3 and m4 can still be considered to be proportional to the distances from the pulling bolt rod to the bottom surface of the concrete beam, and the sum of the four is 1, and Figure 13 H S ≤H S , in the calculation of β b , H S is taken as H S , and when H S >H S , in the calculation of β b , H S is taken as

[0226] The model is applicable to the equal spacing arrangement of the pulling bolt rod and the arrangement with little difference in spacing.

[0227] Specifically, the mechanical anchor is fixedly connected to the top end of the first beam body and the bottom end of the second beam body.

[0228] The bearing capacity estimation model of the mechanical anchor in the composite beam joint is:

[0229] V 机械锚栓 = α s f ys A ss , (38)

[0230] Wherein, f ys represents the yield strength of the mechanical anchor, A ss represents the effective stress cross-sectional area of the mechanical anchor, and α s represents the bearing capacity coefficient of the mechanical anchor.

[0231] For the ultimate bearing capacity of the mechanical anchor under large edge distance and large spacing, α s is 0.75.

[0232] Specifically, in this embodiment of the invention, the ultimate bearing capacity of the mechanical anchor bolt is verified based on a three-element numerical model, as shown in Figure 6.

[0233] Table 6

[0234]

[0235] l represents the total length of the three-element numerical analysis model. Specifically, a composite beam node is considered one element, and each composite beam node includes multiple U-shaped connectors. V u32 This represents the ultimate bearing capacity of the intermediate unit in the three-element numerical analysis model.

[0236] Preferably, the target bearing capacity model is:

[0237]

[0238] Wherein, n1 represents the number of U-shaped connectors in the composite beam node, and n2 represents the number of mechanical anchors in the composite beam node.

[0239] It should be noted that the U-shaped connector mainly contributes V to the shear capacity of the composite beam joint. V And for the sake of conservatism in the load-bearing capacity estimation, therefore, V V The ultimate bearing capacity of the composite beam joint is calculated using the bearing capacity calculation method for mechanical anchors. The target bearing capacity model is as follows:

[0240]

[0241] Preferably, for cases where the width, thickness, and material of the U-shaped connector are all set to be large, an upper limit is determined for the arrangement of 3 and 4 bolts. Specifically, the formula is as follows:

[0242] V u32 ≤(n11.3f yd A' s +n20.75f ys A SS (41)

[0243] Among them, A' S f represents the effective cross-sectional area of ​​a single tie rod. yd This indicates the yield strength of the tie rod.

[0244] To illustrate the beneficial effects of the embodiments of this application, this application mainly utilizes parameter determination when arranging four rows of tie rods. To verify its applicability, data calculation and comparative analysis were performed on the arrangements of 1, 2, 3, and 5 rows of tie rods. The comparative analysis diagram is shown below. Figure 20 As shown, from Figure 19As can be seen, the target bearing capacity calculation model is compared with the finite element analysis, and it is found that the calculation value of the target bearing capacity calculation model is basically below the finite element calculation value, and the error is basically within 10%, which shows that the established target bearing capacity calculation model can ensure relative safety and high precision.

[0245] It should be noted that the "x" involved in the calculation formula in the embodiment of the specification is multiplication.

[0246] The composite beam node bearing capacity estimation method provided by the embodiment of the application has the following advantages. On the one hand, by performing stress analysis on the composite beam node, a balance relationship between force and bending moment is established, and then a bearing capacity calculation model of the U-shaped connecting piece is obtained, and a bearing capacity calculation model of the mechanical anchor bolt in the composite beam node is established. Based on the two bearing capacity calculation models, the known parameters of the composite beam node can be directly input to quickly estimate the ultimate bearing capacity of the composite beam node. The calculation is simple, the calculation amount is small, and the efficiency is high, so the method is convenient for efficient use in actual building engineering. On the other hand, by calibrating the parameters in the bearing capacity calculation model of the U-shaped connecting piece, and introducing the width-thickness ratio influence coefficient of the U-shaped connecting piece, the width-height ratio influence coefficient, the row number influence coefficient of the pull bolt, and the material quality influence coefficient, the estimation model is optimized to obtain a high-precision estimation model, effectively improving the calculation precision of the node shear bearing capacity, and fully improving the cost control level of the node engineering application.

[0247] The above describes only the preferred specific embodiments of the application, but the protection scope of the application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A method for estimating the bearing capacity of composite beam joints, characterized in that, The composite beam node is used to connect the first beam and the second beam in the composite beam. The node includes a U-shaped connector. The second beam is fixedly connected to the open end of the U-shaped connector, and the first beam is fixedly connected to the area enclosed by the U-shaped connector and the second beam. Based on the stress analysis of the U-shaped connector, the equilibrium relationship between the force and bending moment on the lower surface of the second beam is established. A bearing capacity estimation model for the U-shaped connector is then established based on this equilibrium relationship. Furthermore, a bearing capacity estimation model for the mechanical anchors in the composite beam joint is established, thereby obtaining a target bearing capacity estimation model. The target bearing capacity estimation model is as follows: Among them, V u32 For the target bearing capacity estimation model, n1 represents the number of U-shaped connectors in the composite beam joint, n2 represents the number of mechanical anchors in the composite beam joint, and α s f represents the bearing capacity coefficient of mechanical anchors. ys A represents the yield strength of the mechanical anchor bolt. ss This represents the effective stress cross-sectional area of ​​the mechanical anchor bolt. V V A is the second shear force on the section where the bending moment is zero at the connection between the U-shaped connector and the first beam. S =tb, where t represents the cross-sectional area of ​​the U-shaped connector, b represents the thickness of the U-shaped connector, and f represents the width of the U-shaped connector. y h represents the yield strength value of the U-shaped connector. s This represents the distance from the section where the bending moment of the U-shaped connector connecting to the first beam is zero to the lower surface of the second beam. The optimized target bearing capacity estimation model is used to estimate the ultimate bearing capacity of the composite beam joint to be evaluated.

2. The method for estimating the bearing capacity of composite beam joints according to claim 1, characterized in that, Also includes: The load-bearing capacity estimation model of the U-shaped connector is modified by introducing the structural influence coefficient and material influence coefficient of the composite beam node, thereby obtaining an optimized load-bearing capacity estimation model of the U-shaped connector.

3. The method for estimating the bearing capacity of composite beam joints according to claim 2, characterized in that, The establishment of the equilibrium relationship between the force and bending moment on the lower surface of the second beam based on the force analysis of the U-shaped connector includes: According to the shear process, the first shear force V experienced by the U-shaped connector at the connection between the U-shaped connector and the upper flange of the second beam is... M The second shear force V experienced by the section where the bending moment is zero at the connection between the U-shaped connector and the first beam. V The vector sum is the ultimate bearing capacity V at the intersection of the U-shaped connector and the lower flange of the second beam, and the equilibrium relationship of the forces on the lower surface of the second beam is established. V V =VV M , Among them, V M V represents the first shear force. V V represents the second shear force, and V represents the ultimate bearing capacity at the intersection of the U-shaped connector and the lower flange of the second beam. According to the shear resistance process, at the section where the U-shaped connector intersects with the lower surface of the lower flange of the second beam, the vector sum of the first bending moment M1 generated by the connection between the U-shaped connector and the second beam and the third bending moment M3 generated by the eccentric tensile force is equal to the second shear force V at the section where the bending moment of the connection between the U-shaped connector and the first beam is zero. V Taking the second bending moment M2 corresponding to the moment of the lower flange of the second beam, the equilibrium relationship of the bending moment on the lower surface of the second beam is established: M2 = M1 + M3, M1 represents the first bending moment, M2 represents the second bending moment, and M3 represents the third bending moment.

4. The method for estimating the bearing capacity of composite beam joints according to claim 3, characterized in that, The method for establishing a load-bearing capacity estimation model for U-shaped connectors based on this balance relationship includes: The first bending moment, the second bending moment, and the third bending moment are expressed in the form of a resultant force as follows: Where N represents the tensile force on the section where the bending moment is zero at the connection between the U-shaped connector and the first beam; h b The height of the second beam is represented by kb, the eccentricity of the tension is represented by b, the width of the connection between the U-shaped connector and the second beam is represented by b, and the width of the U-shaped connector is represented by k. Based on the aforementioned balance relationship, a load-bearing capacity estimation model for the U-shaped connector is established: in, 5. The method for estimating the bearing capacity of composite beam joints according to claim 4, characterized in that, Also includes: The parameters in the load-bearing capacity estimation model of the U-shaped connector were calibrated using numerical simulation: The first distance is calibrated: The moment of the bottom surface of the first beam is taken using the shear force on the section where the bending moment is zero at the connection between the U-shaped connector and the first beam: M' represents the fourth bending moment obtained after taking the moment, n represents the number of rows of tie rods provided on the U-shaped connector, i represents the i-th row of tie rods arranged sequentially from the open end of the U-shaped connector to its bottom, and h represents the distance from the section where the fourth bending moment is zero to the first row of tie rods. i F represents the distance from the i-th row of tie rods to the bottom surface of the first beam. i β represents the shear force on the i-th row of tie rods, and β represents the bearing capacity coefficient. The influence definition function is characterized by the bending moment obtained by taking moments on the bottom surface of the first beam using the fourth bending moment and the shear force on each row of tie rods. The influence definition function is the influence function of the bottom surface constraint effect and bending effect of the first beam on the redistribution of internal forces. in, Indicates the influence on the defined function, F i =m i ×V V , make After transforming the function defining the influence, we can obtain: The first distance h is determined using the following formula based on the transformed effect definition function. s : Among them, H b This indicates the height of the first beam.

6. The method for estimating the bearing capacity of composite beam joints according to claim 5, characterized in that, The model for estimating the bearing capacity of the U-shaped connector is modified by introducing the influence coefficient of the composite beam node structure, including: Introducing the aspect ratio of the U-shaped connector to the first distance h s Make corrections: Where t represents the thickness of the U-shaped connector, α b This represents the bending deformation coefficient of the U-shaped connector.

7. The method for estimating the bearing capacity of composite beam joints according to claim 6, characterized in that, The correction of the U-shaped connector bearing capacity estimation model by introducing the influence coefficient of the composite beam node structure also includes: Introducing the aspect ratio of the U-shaped connector to the first distance h s Make corrections: Where, β b H represents the aspect ratio influence coefficient of the U-shaped connector. s "" indicates the nominal distance from the first row of tie rods to the lower surface of the second beam when the spacing of the tie rods in each row changes.

8. The method for estimating the bearing capacity of composite beam joints according to claim 7, characterized in that, The correction of the U-shaped connector bearing capacity estimation model by introducing the influence coefficient of the composite beam node structure also includes: The model for estimating the bearing capacity of the U-shaped connector is modified by introducing a material influence coefficient for the composite beam joint, including: Introducing the material influence coefficient of the U-shaped connector to the first distance h s Make corrections: Where, ζ b E represents the material influence coefficient. s This represents the elastic modulus of the U-shaped connector.

9. The method for estimating the bearing capacity of composite beam joints according to claim 8, characterized in that, The correction of the U-shaped connector bearing capacity estimation model by introducing the influence coefficient of the composite beam node structure also includes: Introducing an influence coefficient on the number of rows of tie rods for the first distance h s Make corrections: When the tie rods in each row are installed at equal intervals When the tie rods in each row are not spaced at equal intervals Among them, H' S λ represents the distance from the first row of tie rods to the lower surface of the second beam. b This represents the influence coefficient of the number of rows of tie rods.

10. The method for estimating the bearing capacity of composite beam joints according to any one of claims 1-9, characterized in that, The mechanical anchor bolts are fixedly connected to the top end of the first beam and the bottom end of the second beam. The bearing capacity estimation model for the mechanical anchors in the composite beam joint is as follows: V 机械锚栓 =a s f ys A ss 。

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