Method for calculating node shear bearing capacity of composite beam

Abstract

The invention relates to the technical field of building structures, in particular to a method for calculating node shear bearing capacity of a composite beam, which comprises the following steps of: decomposing the shear bearing capacity of a node core area into shear contribution components of a square steel tube web, encased concrete and a steel wire mesh, and respectively calculating the shear bearing capacity based on respective structural characteristics and stress mechanisms; the total shear bearing capacity is obtained through superposition; and each component is quantized by introducing correction coefficients of an axial compression ratio and a beam-column linear stiffness ratio. According to the method, the technical blank of shear resistance calculation of the concrete joint in the core-free area is filled, the error is controlled within + / -15%, and the method has the characteristic of high precision, is suitable for design of the composite beam joint filled with the concrete in the core-free area in a high-rise building and an underground structure, is high in engineering applicability and provides a reliable calculation basis for design of related building structures.

Description

Technical Field

[0001] The invention relates to the technical field of building structures, in particular to a method for calculating the shear bearing capacity of a node of a composite beam. Background Art

[0002] In the field of modern architecture, the large-scale construction of high-rise and super-high-rise buildings and the deep development of underground space have made structural safety and seismic performance the key control indicators of design; as the core link of structural force transmission, the shear bearing capacity of the node directly determines the reliability of the overall structure; especially in the square hollow steel tube concrete composite column-hollow outer concrete composite beam node, the accurate evaluation of the shear bearing capacity is particularly complex, which is mainly due to its unique structural characteristics and force mechanism; although the current specifications have provided basic design criteria, they have failed to fully consider the structure without concrete filling in the square steel tube, which may lead to the risk of underestimation or overestimation of the shear bearing capacity in actual engineering applications.

[0003] The node of square hollow steel tube concrete composite column-hollow outer concrete composite beam is a structure in which neither the inside of the square steel tube column nor the inside of the steel beam flange is filled with concrete, but only the concrete is wrapped on the outside of the steel, thereby reducing the weight and providing fire protection and corrosion protection for the internal steel structure. At present, there is a lack of research on the precise calculation method of the shear bearing capacity of the square hollow steel tube concrete composite column-hollow outer concrete composite beam node, especially the existing research focuses on the research of steel tube concrete columns and composite columns filled with core concrete. When there is no concrete filled inside, it will affect the internal force and deformation distribution of the node under reciprocating load, so that its failure mode, hysteresis curve, bearing capacity, ductility and energy dissipation capacity are changed. In view of this, a method for calculating the shear bearing capacity of the node of the composite beam is proposed to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the shear bearing capacity of a node of a composite beam to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for calculating the shear bearing capacity of a node of a composite beam comprises the following steps:

[0007] Step S1, decomposing the shear bearing capacity of the core area of ​​the node into shear contribution components of the square steel tube web, the outer concrete and the wire mesh;

[0008] Step S2, based on the node structural characteristics and the force mechanism, respectively calculating the shear bearing capacity components of the square steel tube web, the outer concrete and the wire mesh;

[0009] Step S3, superimpose each component to obtain the total shear bearing capacity of the node; wherein, the shear bearing capacity component of the outer concrete is quantified by introducing the correction coefficient of the axial compression ratio and the beam-column linear stiffness ratio, the shear bearing capacity component of the square steel tube web is calculated based on the yield strength of the steel, and the shear bearing capacity component of the wire mesh is calculated based on its distribution spacing and yield strength.

[0010] Preferably, the total shear capacity is calculated as follows:

[0011] The total shear capacity is equal to the sum of the shear capacity of the outer concrete, the shear capacity of the square steel tube web and the shear capacity of the wire mesh; where:

[0012] The shear bearing capacity of the outer concrete is: the product of the axial compression ratio correction factor and the beam-column linear stiffness ratio correction factor, multiplied by the concrete tensile strength and shear cross-sectional area; the axial compression ratio correction factor is 1.40 minus 0.80 times the axial compression ratio, and the beam-column linear stiffness ratio correction factor is 0.95 minus 0.16 times the beam-column linear stiffness ratio; the axial compression ratio ranges from 0.4 to 0.8, and the beam-column linear stiffness ratio ranges from 0.3 to 1.2;

[0013] The shear bearing capacity of the square steel tube web is: the product of the cross-sectional area of ​​the square steel tube web and the yield strength of the steel, divided by ;

[0014] The shear bearing capacity of the wire mesh is: the product of the yield strength of the wire mesh and the total cross-sectional area of ​​each limb of the wire mesh in the same section, multiplied by the upper and lower longitudinal wire mesh spacing of the beam section, and then divided by the wire mesh spacing in the core area of ​​the node.

[0015] Preferably, the axial compression ratio is defined as the ratio of the design value of the column axial pressure to the product of the axial compressive strength of the outer concrete and the cross-sectional area of ​​the outer concrete plus the product of the yield strength of the steel and the cross-sectional area of ​​the square steel tube.

[0016] Preferably, the beam-to-column linear stiffness ratio is defined as the product of the elastic modulus, the section moment of inertia and the calculated length ratio of the beam, divided by the product of the elastic modulus, the section moment of inertia and the calculated length ratio of the column.

[0017] Preferably, the tensile strength of the outer casing concrete is calibrated by experiments, and the axial compression ratio correction factor and the beam-column linear stiffness ratio correction factor are determined based on finite element parameter sensitivity analysis and test data fitting.

[0018] Preferably, the node structure satisfies the following conditions:

[0019] The square steel tube column has no concrete filling inside, but is wrapped with fiber concrete and equipped with steel mesh outside;

[0020] The flange of the steel beam is filled with lightweight blocks, wrapped with fiber concrete and equipped with steel mesh, and poured with ordinary concrete on the top;

[0021] The wire mesh is evenly distributed along the beam section, and the spacing meets the limit of 30 mm to 0.5 times the shear section height.

[0022] Preferably, the ratio of the shear section height to width does not exceed 3.0.

[0023] Preferably, the yield strength of the steel mesh is not less than 300 MPa, and the total cross-sectional area accounts for 0.5% to 2.0% of the cross-sectional area of ​​the outer concrete.

[0024] Compared with the prior art, the present invention focuses on the shear bearing capacity calculation method of the square hollow steel tube concrete composite column-hollow outer concrete composite beam node, and its beneficial effects are mainly reflected in the following aspects:

[0025] Filling the technical gap: In the prior art, the shear bearing capacity calculation of steel tube concrete composite column nodes is mostly based on the structure of internally filled concrete. There is a lack of effective calculation methods for square hollow steel tube concrete composite column-hollow outer concrete composite beam nodes without core area concrete filling. The present invention is the first shear formula for such core-free concrete nodes by decomposing shear components and introducing correction coefficients, filling the gap in this technical field and providing an important theoretical basis and calculation method for the design and analysis of this type of nodes.

[0026] High precision: The calculation method proposed in the present invention can more accurately reflect the stress performance of the node by reasonably decomposing the shear bearing capacity of the core area of ​​the node, considering the shear contribution of the square steel tube web, the outer concrete and the wire mesh, and introducing the correction coefficient of the axial compression ratio and the beam-column linear stiffness ratio. From the examples and experimental verification, the error between the formula calculation results and the finite element results is less than ±15%, which is significantly better than the traditional method, and can provide more reliable calculation results for engineering design, reducing the structural safety hazards caused by calculation errors.

[0027] Comprehensive consideration of factors: the existing formula ignores the "tension belt" mechanism of the square steel tube web when there is no core area concrete, the inability of the outer concrete to form an effective diagonal compression rod stress mode, and the influence of the axial compression ratio and the beam-column line stiffness ratio on the bearing capacity. The present invention fully considers these key factors, making the calculation model more consistent with the actual structural stress conditions, and can more comprehensively and accurately evaluate the shear bearing capacity of the node;

[0028] Strong engineering applicability: The calculation method of the present invention is applicable to the design of composite beam nodes without core area concrete filling in high-rise buildings and underground structures, meeting the requirements for lightweight and safe design in actual projects; whether in the structural design of high-rise buildings or in the design of composite beam nodes in underground structures that need to reduce deadweight and require fire and corrosion resistance, it can provide engineers with effective calculation tools, help optimize structural design, and improve project quality and safety;

[0029] Close integration of theory and practice: The present invention not only conducts an in-depth analysis of the shear mechanism of the node in theory and establishes a reasonable calculation model and formula, but also verifies the reliability and effectiveness of the method through multiple embodiments and a large number of experiments; this close integration of theory and practice makes the calculation method of the present invention more convincing and practical, and can be better applied to actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a schematic flow chart of a method for calculating the shear bearing capacity of a node of a composite beam. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0033] Example:

[0034] See also Figure 1 , this embodiment provides a technical solution:

[0035] A method for calculating the shear bearing capacity of a node of a composite beam comprises the following steps:

[0036] Step S1, decomposing the shear bearing capacity of the core area of ​​the node into shear contribution components of the square steel tube web, the outer concrete and the wire mesh;

[0037] Step S2: Based on the node structure characteristics and the force mechanism, the shear bearing capacity components of the square steel tube web, the outer concrete and the wire mesh are calculated respectively. The node structure meets the following conditions:

[0038] The square steel tube column has no concrete filling inside, and is wrapped with fiber concrete (strength grade ≥ C30, thickness ≥ 60mm) on the outside and equipped with wire mesh (square mesh shape, side length 30mm). The wire mesh is evenly distributed along the column height with a spacing of 30mm.

[0039] The flange of the steel beam is filled with lightweight blocks (density ≤ 800kg / m³), wrapped with fiber concrete (thickness ≥ 50mm) and equipped with wire mesh (square mesh shape, side length 40mm), and poured with ordinary concrete (strength grade ≥ C30) on the top;

[0040] The wire mesh is evenly distributed along the beam section, with a spacing of 30mm-0.5 times the shear section height ( ), yield strength ≥ 300MPa, total cross-sectional area accounts for 0.5%-2.0% of the cross-sectional area of ​​the outer concrete, and the spacing meets the limit of 30mm to 0.5 times the shear section height;

[0041] Step S3, superimposing each component to obtain the total shear bearing capacity of the node; wherein the shear bearing capacity component of the outer concrete is quantified by introducing the correction coefficient of the axial compression ratio and the beam-column linear stiffness ratio, the shear bearing capacity component of the square steel tube web is calculated based on the yield strength of the steel material, and the shear bearing capacity component of the wire mesh is calculated based on its distribution spacing and yield strength;

[0042] The calculation formula for the total shear capacity is:

[0043] The total shear capacity is equal to the sum of the shear capacity of the outer concrete, the shear capacity of the square steel tube web and the shear capacity of the wire mesh; where:

[0044] The shear bearing capacity of the outer concrete is: the product of the axial compression ratio correction factor and the beam-column linear stiffness ratio correction factor, multiplied by the concrete tensile strength and shear cross-sectional area; the axial compression ratio correction factor is 1.40 minus 0.80 times the axial compression ratio, and the beam-column linear stiffness ratio correction factor is 0.95 minus 0.16 times the beam-column linear stiffness ratio; the axial compression ratio ranges from 0.4 to 0.8, and the beam-column linear stiffness ratio ranges from 0.3 to 1.2;

[0045] The shear bearing capacity of the square steel tube web is: the product of the cross-sectional area of ​​the square steel tube web and the yield strength of the steel, divided by ;

[0046] The shear bearing capacity of the wire mesh is: the product of the wire mesh yield strength and the total cross-sectional area of ​​each limb of the wire mesh in the same section, multiplied by the longitudinal wire mesh spacing above and below the beam section, divided by the wire mesh spacing in the core area of ​​the node;

[0047] The axial compression ratio is defined as the ratio of the design value of the column axial pressure to the product of the axial compressive strength of the outer concrete and the cross-sectional area of ​​the outer concrete plus the product of the yield strength of the steel and the cross-sectional area of ​​the square steel tube;

[0048] The beam-to-column linear stiffness ratio is defined as the product of the elastic modulus, section moment of inertia, and calculated length ratio of the beam, divided by the product of the elastic modulus, section moment of inertia, and calculated length ratio of the column;

[0049] The tensile strength of the outer casing concrete is calibrated through experiments, and the axial compression ratio correction factor and the beam-column linear stiffness ratio correction factor are determined based on the finite element parameter sensitivity analysis and test data fitting.

[0050] In this embodiment, the function of step S1 is to accurately analyze the constituent elements of the shear bearing of the core area of ​​the node, laying the foundation for the subsequent accurate calculation of the shear contribution of each part; through in-depth exploration of the node structure characteristics and mechanical principles, the main sources of shear contribution are clearly defined, and the specific steps are as follows:

[0051] Step S1-1: Collect and analyze basic information related to the node:

[0052] Node structure data collection: Comprehensively collect detailed structural data of the square hollow steel tube concrete composite column-hollow outer concrete composite beam node; cover the geometric dimensions of the square steel tube column, including precise parameters such as side length and wall thickness; various properties of the outer concrete, such as outer thickness, strength grade, mix ratio and pouring range; key dimensions and structural details of the part connected to the node of the hollow outer concrete composite beam, such as the cross-sectional shape, size and internal reinforcement of the beam; ensure the integrity and accuracy of the collected data through various methods such as field measurement, design drawing review and relevant construction record collation;

[0053] Material mechanical properties investigation: For the main materials involved in the node, i.e., the steel of the square steel tube, the outer concrete and the wire mesh, their mechanical properties are investigated in depth; for steel, key mechanical indicators such as yield strength, ultimate strength and elastic modulus are obtained. These data can usually be obtained from the quality inspection report or relevant standard tests provided by the steel manufacturer; for the outer concrete, its axial compressive strength, tensile strength and elastic modulus and other parameters are determined through standard specimen tests; for the wire mesh, its yield strength, mesh size and wire diameter and other key factors affecting its mechanical properties are mastered; these material mechanical properties data are combined to provide a basic basis for the subsequent analysis of the role of each part in the shear resistance of the node;

[0054] Step S1-2: Analyze the shear bearing structure of the core area of ​​the node:

[0055] Analysis of mechanical principles: Based on the basic principles of structural mechanics and material mechanics, the mechanical behavior of the core area of ​​the node when subjected to shear force is deeply analyzed; when the node is subjected to shear force, the transmission path and distribution method of force between the square steel tube column, the outer concrete and the wire mesh are the key to the analysis; the square steel tube column plays an important role in the shear resistance of the node due to the good shear resistance of the steel, and its web can directly bear part of the shear force and resist external forces through the yielding and deformation of the steel; in the process of working in coordination with the square steel tube, the outer concrete also contributes to the shear bearing capacity of the node by virtue of its own compression and tension resistance, and plays a role in restraining the deformation of the square steel tube, thereby enhancing the overall stability of the node; the wire mesh can effectively prevent the development and expansion of concrete cracks due to its uniform distribution in the core area of ​​the node, improve the integrity of the core area of ​​the node, and thus indirectly improve the shear resistance of the node;

[0056] Determine the main contributors to shear resistance: Through a detailed analysis of the mechanical behavior of the core area of ​​the node, combined with the collected structural data and material mechanical properties information, it is clear that the square steel tube web, external concrete and wire mesh are the main contributors to the shear bearing capacity of the core area of ​​the node; from the perspective of structural construction and mechanical properties, these three parts work together and cooperate with each other in the shear resistance of the node; the square steel tube web is the key part that directly bears the shear force, and its shear resistance directly affects the overall shear performance of the node; the external concrete not only has a certain shear resistance itself, but also can form a combined structure with the square steel tube to enhance the bearing capacity of the node; the wire mesh further improves the shear bearing capacity of the node by improving the performance of the concrete in the core area of ​​the node; clarifying these three main contributors to shear resistance provides a clear direction for the subsequent calculation of the shear bearing capacity components of each part.

[0057] In this embodiment, the function of step S2 is to accurately calculate the shear bearing capacity components of the square steel tube web, the outer concrete and the wire mesh according to the specific structural characteristics and the internal force mechanism of the node, so as to provide key data support for obtaining the total shear bearing capacity of the node; the specific steps are as follows:

[0058] Step S2-1: Calculate the shear bearing capacity component of the square steel tube web:

[0059] Determine web-related parameters: Accurately measure key parameters of square steel tube webs, including the cross-sectional area of ​​the webs ; By measuring the side length and wall thickness of the square steel tube, the web cross-sectional area can be accurately calculated according to the corresponding geometric formula; at the same time, the yield strength of the steel used can be determined , this parameter can be obtained from the quality inspection report of steel or standard test data;

[0060] Use shear calculation formula: Based on the mechanical properties of steel and structural shear theory, a specific calculation formula is used to determine the shear bearing capacity of the square steel tube web The calculation formula is This formula fully considers the yield characteristics of steel and the mechanical behavior of the web under shear force. Yield strength of steel Substituting into the formula, the bearing capacity component contributed by the square steel tube web in the node shear resistance can be accurately calculated; among them, , is the web thickness, is the web height (need to deduct the corner weld influence area, and take the value according to the actual net height); steel yield strength According to the "Steel Structure Design Standard" (GB50017), the standard value of steel yield strength is taken 0.9 times of the design value ( );

[0061] Step S2-2: Calculate the shear bearing capacity component of the outer concrete:

[0062] Obtaining concrete and related parameters: Determining the axial compressive strength of the outer casing concrete through standard tests and tensile strength , steel yield strength ; At the same time, measure the cross-sectional area of ​​the outer concrete , Square steel tube cross-sectional area , Cross-sectional area of ​​unfilled concrete And the height of the shear section in the core area of ​​the node and width ; In addition, determine the axial pressure ratio The beam-column linear stiffness ratio The value of axial pressure ratio By formula It is calculated that, is the design value of the column axial pressure (load combination is required according to the Code for Seismic Design of Buildings (GB50011)); beam-column linear stiffness ratio By formula Calculation, where is the bending stiffness of the beam , and are the cross-sectional moments of inertia of concrete and steel, and are the elastic moduli of concrete and steel, For the beam length; is the bending stiffness of the column , and are the cross-sectional inertia moments of concrete and square steel tube, respectively. and are the elastic moduli of concrete and square steel tube, is the column height;

[0063] Application of shear bearing capacity formula: Based on the stress characteristics of the outer concrete in the node and a large amount of test data and theoretical research results, the formula ( , , ) to calculate its shear bearing capacity ; This formula introduces the axial pressure ratio The beam-column linear stiffness ratio The correction factor takes into account the tensile strength of the outer concrete. , concrete shear cross-sectional area (Wherein, the shear section height The height of the concrete section outside the core area of ​​the node and the width of the shear section is the width of the outer concrete section, is the cross-sectional area of ​​the unfilled concrete) and the axial compression ratio The beam-column linear stiffness ratio The influence of the shear performance on it; Substituting the accurately obtained parameters into this formula, the bearing capacity component provided by the outer concrete in the node shear resistance can be obtained; Among them, the tensile strength of the outer concrete The method of obtaining is as follows: According to the "Concrete Structure Test Method Standard" (GB / T50152), the splitting tensile test method is used, and three groups of 150mm×150mm×150mm cubic specimens are taken. The test loading rate is controlled at 0.05MPa / s-0.08MPa / s, and the average value is taken as ;

[0064] The correction factor is derived based on:

[0065] Axial pressure ratio correction factor :

[0066] Based on 32 sets of finite element model parameter sensitivity analysis (axial pressure ratio The range of variation is ,Through multiple linear regression fitting, the goodness of fit is obtained , the formula is applicable to ;

[0067] Correction factor of beam-column linear stiffness ratio :

[0068] Through 18 groups of node test data The range of variation is The fitting equation is: , in , applicable scope is ;

[0069] Step S2-3: Calculate the shear bearing capacity component of the wire mesh:

[0070] Clarify the relevant parameters of the wire mesh: Carefully measure the key parameters of the wire mesh, including the layout spacing of the wire mesh in the core area of ​​the node , by actually measuring the spacing of the wire mesh in the core area of ​​the node; calculate the total cross-sectional area of ​​the wire mesh , calculate according to the mesh size, wire diameter and layout range of the wire mesh; determine the yield strength of the wire mesh This parameter can be obtained from the product manual of the wire mesh or the relevant material performance test report. For example, according to the "Tensile Test of Metal Materials" (GB / T228.1), 5 steel wire specimens are cut with a gauge length of 100mm and a loading rate of 1mm / min. The breaking strength is recorded and the minimum value is taken as ; At the same time, measure the longitudinal wire mesh spacing of the beam section ( is the effective height of the beam section, is the thickness of the protective layer);

[0071] Calculate shear capacity: Based on the mechanism of action of the wire mesh in the node and the mechanical principle, use the formula ( , It accounts for 0.5%-2.0% of the concrete cross-sectional area. , It is the total cross-sectional area of ​​each limb of the wire mesh in the same section, ranging from 30 mm to 0.5 times the shear section height , , in, is the number of wire mesh layers, is the number of single-layer wire mesh limbs, is the wire diameter) to calculate the shear bearing capacity of the wire mesh ,like , according to Value; if , the wire mesh layout plan needs to be readjusted; the formula comprehensively considers the influence of factors such as the yield strength, total cross-sectional area, spacing of the wire mesh and the longitudinal wire mesh spacing of the beam section on its shear capacity; the various parameters accurately measured and obtained are substituted into the formula to accurately calculate the bearing capacity component contributed by the wire mesh in the node shear process.

[0072] In this embodiment, the function of step S3 is to obtain the total shear bearing capacity of the node by comprehensively considering various factors, so as to provide key data for evaluating the performance of the node; the specific steps are as follows:

[0073] Step S3-1: Integrate the shear capacity components:

[0074] Collect sub-item calculation results: Obtain the calculated shear bearing capacity of the square steel tube web from step S2 Shear bearing capacity of external concrete And the shear bearing capacity of wire mesh These values ​​are based on their respective calculation formulas and are obtained by accurately measuring and obtaining relevant parameters;

[0075] Establish a data integration process: Develop a rigorous data integration process to ensure that the data of each sub-item bearing capacity can be accurately summarized; clarify the source path and verification method of the data, and recheck the shear bearing capacity component data obtained from different calculation links to avoid result deviation due to data transmission or recording errors;

[0076] Step S3-2: Calculate the total shear capacity:

[0077] Apply the total capacity formula: Apply the formula To calculate the total shear capacity of the node ; This formula intuitively reflects that the total shear bearing capacity of the node is composed of the shear bearing capacity components of the outer concrete, square steel tube web and wire mesh; and Substitute the values ​​into the formula to perform addition operations;

[0078] Guarantee the accuracy of the calculation process: When performing formula calculations, high-precision calculation tools are used, and the calculation process is reviewed multiple times; for the numerical calculations involved, especially decimal calculations and priority calculations in complex formulas, they are strictly carried out in accordance with mathematical operation rules to ensure the accuracy of the calculation results; for example, when calculating the shear bearing capacity of the outer concrete When there are multiple multiplication and addition and subtraction operations of parameters in the formula, when substituting them into the total shear bearing capacity formula for calculation, it is necessary to ensure that the operation order and result of each parameter are correct;

[0079] Step S3-3: Verify the total shear capacity calculation results:

[0080] Set the allowable error range: According to relevant industry standards and engineering experience, the acceptable error range between the calculated value and the actual value is set to ±15%; the setting of this error range comprehensively considers the simplification of the calculation model, the error of parameter measurement and the influence of various complex factors in actual engineering. The calculation results within this range are considered to meet the requirements of engineering design and safety assessment;

[0081] Compare the calculated value with the actual value: obtain the actual shear bearing capacity of the node through finite element simulation or test; in finite element simulation, establish an accurate node model, simulate the actual stress condition, and obtain the simulated actual shear bearing capacity value; in the test, build a test device according to strict test standards, load test the node, and record the shear bearing capacity data at the time of failure; calculate the total shear bearing capacity Compare with the actual shear capacity obtained by the above method;

[0082] Evaluate the validity of the calculation results: determine whether the calculated value is within the set allowable error range based on the comparison results; if the error between the calculated value and the actual value is within ±15%, the total shear bearing capacity calculation formula is determined to be valid and can be used for the calculation and evaluation of the shear bearing capacity of nodes in actual projects; if the error exceeds this range, it is necessary to conduct a comprehensive check on the calculation process, including whether the parameter values ​​are accurate, whether the calculation formula is correctly applied, etc. At the same time, the finite element simulation model or test process should be reviewed to find out the possible causes of the deviation, and the calculation method should be corrected and improved before verification again.

[0083] The present invention will be further described below in conjunction with specific embodiments:

[0084] Example 1: Node design of a high-rise building:

[0085] Node construction:

[0086] Square steel column:

[0087] The cross-sectional dimensions of the square steel tube are 400mm×400mm, the steel strength is Q235, and the wall thickness is 12mm;

[0088] No concrete filling inside, C30 fiber concrete wrapped outside ) thickness is 60 mm;

[0089] Configure a single layer of orthogonal square wire mesh (mesh side length 30mm), wire diameter 5mm, longitudinal spacing 30mm ( );

[0090] Steel beam:

[0091] Section model: H400×200×8×10 (flange thickness 10mm, web thickness 8mm);

[0092] The flange is filled with lightweight blocks (density 600kg / m³) and wrapped with C30 fiber concrete (thickness 50mm) on the outside;

[0093] The thickness of C30 ordinary concrete poured on the top is 100mm;

[0094] Configure a single-layer longitudinal square steel wire mesh (mesh side length 40mm), yield strength ;

[0095] Material parameter test method:

[0096] Concrete tensile strength: According to the "Concrete Structure Test Method Standard" (GB / T50152), the splitting tensile test was adopted, and the loading rate of 3 groups of 150mm cubic specimens was 0.06MPa / s, and the average tensile strength was measured to be 3.34MPa;

[0097] Yield strength of wire mesh: According to "Tensile Test of Metal Materials" (GB / T228.1), 5 steel wire specimens with a gauge length of 100mm were cut, and the loading rate was 1mm / min. The minimum yield strength was measured to be 611MPa;

[0098] Parameter calculation:

[0099] Axial pressure ratio calculate:

[0100] Design value of column axial pressure: ; , ;

[0101] Square steel tube cross-sectional area: ;

[0102] External concrete cross-sectional area: ;

[0103] Axial pressure ratio formula: (satisfy );

[0104] Beam-to-column linear stiffness ratio calculate:

[0105] Bending stiffness of steel beam:

[0106] Elastic modulus of steel: ;

[0107] Modulus of elasticity of concrete: ;

[0108] Steel section moment of inertia (H400×200×8×10): ;

[0109] Moment of inertia of outer concrete: ;

[0110] Calculation results: , ;

[0111] Bending stiffness of square steel pipe column:

[0112] Square steel tube moment of inertia: ;

[0113] Moment of inertia of outer concrete: ;

[0114] Calculation results: , ;

[0115] Beam-to-column linear stiffness ratio: (satisfy );

[0116] Shear bearing capacity of external concrete calculate:

[0117] Shear section height:

[0118] Shear section width: ;

[0119] Unfilled concrete cross-sectional area: ;

[0120] Calculation formula: ;

[0121] Shear bearing capacity of square steel tube webs calculate:

[0122] Web cross-sectional area: , ;

[0123] Calculation formula: ;

[0124] Shear bearing capacity of wire mesh :

[0125] Total cross-sectional area (single layer, two limbs per layer): , , ;

[0126] Calculation formula: ;

[0127] Total shear capacity : ;

[0128] verify:

[0129] Finite element simulation results: ;

[0130] error: ,satisfy Require.

[0131] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the shear bearing capacity of a node of a composite beam, characterized in that: The following steps are involved: Step S1, decomposing the shear bearing capacity of the core area of ​​the node into shear contribution components of the square steel tube web, the outer concrete and the wire mesh; Step S2, based on the node structural characteristics and the force mechanism, respectively calculating the shear bearing capacity components of the square steel tube web, the outer concrete and the wire mesh; Step S3, superimposing each component to obtain the total shear bearing capacity of the node; wherein the shear bearing capacity component of the outer concrete is quantified by introducing a correction coefficient of the axial compression ratio and the beam-to-column linear stiffness ratio, the shear bearing capacity component of the square steel tube web is calculated based on the yield strength of the steel, and the shear bearing capacity component of the wire mesh is calculated based on its distribution spacing and yield strength.

2. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 1, characterized in that: The total shear capacity is calculated as follows: The total shear capacity is equal to the sum of the shear capacity of the outer concrete, the shear capacity of the square steel tube web and the shear capacity of the wire mesh; where: The shear bearing capacity of the outer concrete is: the product of the axial compression ratio correction coefficient and the beam-column line stiffness ratio correction coefficient, multiplied by the concrete tensile strength and shear cross-sectional area; the axial compression ratio correction coefficient is 1.40 minus 0.80 times the axial compression ratio, and the beam-column line stiffness ratio correction coefficient is 0.95 minus 0.16 times the beam-column line stiffness ratio; the axial compression ratio ranges from 0.4 to 0.8, and the beam-column line stiffness ratio ranges from 0.3 to 1.2; The shear bearing capacity of the square steel tube web is: the product of the cross-sectional area of ​​the square steel tube web and the yield strength of the steel divided by ; The shear bearing capacity of the wire mesh is: the product of the yield strength of the wire mesh and the total cross-sectional area of ​​each limb of the wire mesh in the same section, multiplied by the upper and lower longitudinal wire mesh spacing of the beam section, and then divided by the wire mesh spacing in the core area of ​​the node.

3. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 2, characterized in that: The axial compression ratio is defined as the ratio of the design value of the column axial pressure to the product of the axial compressive strength of the outer concrete and the cross-sectional area of ​​the outer concrete plus the product of the yield strength of the steel and the cross-sectional area of ​​the square steel tube.

4. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 2, characterized in that: The beam-to-column linear stiffness ratio is defined as the product of the elastic modulus, the section moment of inertia and the calculated length ratio of the beam, divided by the product of the elastic modulus, the section moment of inertia and the calculated length ratio of the column.

5. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 2, characterized in that: The tensile strength of the outer concrete is calibrated through experiments, and the axial compression ratio correction factor and the beam-column linear stiffness ratio correction factor are determined based on finite element parameter sensitivity analysis and test data fitting.

6. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 1, characterized in that: The node structure meets the following conditions: The square steel tube column has no concrete filling inside, but is wrapped with fiber concrete and equipped with steel mesh outside; The flange of the steel beam is filled with lightweight blocks, wrapped with fiber concrete and equipped with wire mesh, and poured with ordinary concrete on the top; The wire mesh is evenly distributed along the beam section, and the spacing meets the limit of 30 mm to 0.5 times the shear section height.

7. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 2, characterized in that: The ratio of the height to the width of the shear section does not exceed 3.

0.

8. The method for calculating the shear bearing capacity of a node of a composite beam according to claim 6, characterized in that: The yield strength of the steel wire mesh is not less than 300 MPa, and the total cross-sectional area accounts for 0.5% to 2.0% of the cross-sectional area of ​​the outer concrete.

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