Shear capacity calculation method of composite shear connectors in steel-uhrp composite structures

Abstract

A method for calculating the shear capacity of a composite shear connector in a steel-UHPC composite structure. The method for calculating the shear capacity of a composite shear connector in a steel-UHPC composite structure is to introduce a UHPC material enhancement coefficient and a group dowel effect enhancement coefficient to obtain a formula for calculating the shear capacity of multiple rows of shear dowels in UHPC; introduce a multi-hole arrangement bearing capacity reduction to obtain a formula for calculating the shear capacity of a PBL connector in UHPC; superimpose the formula for calculating the shear capacity of multiple rows of shear dowels in UHPC and the formula for calculating the shear capacity of a PBL connector, and introduce a composite reduction effect to obtain a formula for calculating the shear capacity of a composite shear connector of shear dowels and PBL in UHPC. The method for calculating the shear capacity of a composite shear connector in a steel-UHPC composite structure accurately reflects the synergistic enhancement and reduction law between the components of the composite connector, and improves the efficiency and accuracy of the design of a steel-UHPC composite beam.

Description

Technical Field

[0001] This application relates to the field of architectural design, and more specifically, to a method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure. Background Technology

[0002] Steel-concrete composite beams are widely used due to their advantages such as reasonable stress distribution, good economy, and convenient construction. Shear studs and PBL connectors are two commonly used connection methods in steel-concrete composite beams. Shear stud connectors have a high degree of standardization and good fatigue resistance, but they are prone to stress concentration leading to concrete cracking. PBL connectors have high shear capacity due to the concrete tenon effect, but their excessive stiffness increases the risk of brittle failure. Ultra-high performance concrete (UHPC) has excellent compressive and tensile strength, high toughness, and low shrinkage characteristics, which can significantly improve the stiffness and ductility of structures. To improve the mechanical properties of composite structures, a composite shear connector is formed by combining the advantages of both shear studs and PBL connectors, which can improve stress distribution and enhance structural performance.

[0003] The existing calculation methods for the shear capacity of composite shear connectors in steel-UHPC composite structures can only use empirical formulas from ordinary concrete structures. These methods cannot fully consider the high-strength confinement effect of UHPC, the reinforcement effect of steel fibers, and the reduction effect of porous arrangement, resulting in large calculation deviations. Summary of the Invention

[0004] The purpose of this application is to provide a method for calculating the shear bearing capacity of composite shear connectors in steel-UHPC composite structures, which can accurately reflect the synergistic enhancement and reduction laws among the components of the composite connector, and significantly improve the efficiency and accuracy of shear connection design for steel-UHPC composite beams.

[0005] This application is implemented as follows: This application provides a method for calculating the shear bearing capacity of composite shear connectors in steel-UHPC composite structures, including the following steps: The effect of UHPC on the shear stud bearing capacity and the mutual influence among multiple rows of shear studs are analyzed. By introducing the UHPC material reinforcement coefficient and the group stud effect reinforcement coefficient, the calculation formula for the shear bearing capacity of multiple rows of shear studs in UHPC is obtained. The shear capacity of PBL connectors is decomposed into end bearing pressure, concrete tenon shear and through steel reinforcement shear. A multi-hole reduction coefficient is introduced to reduce the bearing capacity caused by the overlap of damage between holes when multiple holes are arranged, so as to obtain the calculation formula of shear capacity of PBL connectors in UHPC. The shear capacity calculation formulas for multi-row shear studs in UHPC and PBL connectors are linearly superimposed, and a composite reduction effect is introduced to obtain the shear capacity calculation formula for the composite connectors of shear studs and PBL connectors in UHPC.

[0006] In some alternative implementations, the formula for calculating the shear capacity of multi-row shear studs in a UHPC is as follows: P u,m as follows: ; In the formula, m is the number of rows of shear studs; A st f is the cross-sectional area of ​​the shear stud. c f st These are the compressive strength of the concrete cube and the tensile strength of the shear studs, respectively; E c E s These are the elastic moduli of concrete and shear studs, respectively. The reinforcement factor of UHPC material reflects the effect of the high strength of UHPC on the bearing capacity of shear studs. It is obtained by fitting experimental data and is taken as 2.164. The group nail effect enhancement coefficient is equal to the ratio of the bearing capacity of a single nail in a multi-row shear nail to the bearing capacity of a single nail in a single-row shear nail, and is obtained by fitting an asymptotic function.

[0007] In some alternative implementations, the swarming effect enhancement coefficient is calculated using the following formula. : ; In the formula, m is the number of rows of shear studs.

[0008] In some alternative implementations, the shear capacity of a single-hole PBL connector in a UHPC The calculation formula is as follows: ; In the formula, P u Shear bearing capacity of a single-hole PBL connector in a UHPC; p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; Ac The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the strength enhancement factor for concrete samples; k is an undetermined coefficient, reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y This represents the yield strength of the through-steel reinforcement.

[0009] In some alternative implementations, the formula for calculating the shear capacity of porous PBL connectors in UHPC. as follows: ; ; In the formula, p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the concrete strength enhancement coefficient; k is an undetermined coefficient reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y n represents the yield strength of the through-bar reinforcement; n is the number of holes in the PBL. This is the reduction factor for the opening.

[0010] In some alternative implementations, It is 0.95. It is 1.06. To get 1.32, k It is 0.07.

[0011] In some optional implementations, the shear capacity calculation formula for the single-row shear stud and single-hole PBL composite connector in UHPC is as follows: ; In the formula, m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f The diameter of the steel fiber; A pr The area of ​​the through-reinforcement; f pr This represents the yield strength of the through-steel reinforcement.

[0012] In some alternative implementations, a It is 2.94. b The value is 0.95, and c is 1.03. d It is 1.32.

[0013] In some optional implementations, the shear capacity calculation formula for multi-row shear studs and multi-hole PBL composite connectors in UHPC is as follows: ; ; In the formula, m 1 represents the total number of shear studs;n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; h Height of the perforated steel plate; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; A s The cross-sectional area of ​​the through-bar; f y The yield strength of the through-bar reinforcement; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f λ is the diameter of the steel fiber; λ is the porosity reduction factor. e This is the net distance between adjacent openings in a PBL perforated plate.

[0014] In some alternative implementations, a It is 2.94. b The value is 0.95, and c is 1.03. d It is 1.32.

[0015] The beneficial effects of this application are as follows: The method for calculating the shear bearing capacity of composite shear connectors in steel-UHPC composite structures provided in this application includes the following steps: analyzing the enhancement effect of UHPC on the shear stud bearing capacity and the mutual influence between multiple rows of shear studs, introducing the UHPC material reinforcement coefficient and the group stud effect reinforcement coefficient, to obtain the calculation formula for the shear bearing capacity of multiple rows of shear studs in UHPC; decomposing the shear bearing capacity of PBL connectors into end bearing pressure, concrete tenon shear resistance, and through steel reinforcement shear resistance, and introducing a multi-hole reduction coefficient to reduce the bearing capacity caused by the overlap of inter-hole damage when multiple holes are arranged, to obtain the calculation formula for the shear bearing capacity of PBL connectors in UHPC; linearly superimposing the calculation formula for the shear bearing capacity of multiple rows of shear studs in UHPC with the calculation formula for the shear bearing capacity of PBL connectors, and introducing a composite reduction effect, to obtain the calculation formula for the shear bearing capacity of composite connectors of shear studs and PBL connectors in UHPC. The shear bearing capacity calculation method for composite shear connectors in steel-UHPC composite structures provided in this application introduces the UHPC material reinforcement coefficient, the group nail effect reinforcement coefficient, and the porous reduction coefficient that is generated by considering the bearing capacity reduction caused by the overlap of inter-hole damage when the porous arrangement is used. This method can accurately reflect the synergistic reinforcement and reduction law between the components of the composite connector, and significantly improve the efficiency and accuracy of shear connection design for steel-UHPC composite beams. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure provided in this application embodiment; Figure 2 A cross-sectional view of a steel-UHPC composite structure from a first perspective, which is part of the method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure provided in the embodiments of this application. Figure 3 This is a cross-sectional view of a steel-UHPC composite structure from a second perspective, which is part of the method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure provided in the embodiments of this application. Figure 4 A third-view sectional view of a steel-UHPC composite structure, which is part of the method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure provided in the embodiments of this application. Figure 5A cross-sectional structural schematic diagram of the S-0-1 specimen in the calculation method for the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application; Figure 6 A cross-sectional structural schematic diagram of specimen S-0-3 in the calculation method of the shear bearing capacity of composite shear connector in steel-UHPC composite structure provided in the embodiments of this application; Figure 7 A cross-sectional structural schematic diagram of the P-1-0 specimen in the calculation method of the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application; Figure 8 A cross-sectional structural schematic diagram of the P-3-0 specimen in the calculation method of the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application; Figure 9 A cross-sectional structural schematic diagram of the SP-1-3 specimen in the shear bearing capacity calculation method of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application; Figure 10 A cross-sectional structural schematic diagram of the SP-2-3 specimen in the calculation method for the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application; Figure 11 This is a cross-sectional structural diagram of the SP-3-3 specimen used in the calculation method for the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure provided in the embodiments of this application.

[0018] In the diagram: 100, H-beam; 110, UHPC concrete layer; 120, shear stud; 130, perforated steel plate; 140, through-bar reinforcement. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] The following describes in further detail the features and performance of the shear bearing capacity calculation method for composite shear connectors in the steel-UHPC composite structure of this application, with reference to embodiments.

[0022] like Figure 1 As shown, this application provides a method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure. The steel-UHPC composite structure consists of a UHPC concrete layer 110 on the surface of the steel plate. The steel plate is connected to single or multiple rows of shear studs 120 embedded in the UHPC concrete layer 110. The steel plate is also connected to perforated steel plates 130 embedded in the UHPC concrete layer 110. Each perforated steel plate 130 has one or more holes. Through-reinforcing bars 140 are embedded in the UHPC concrete layer 110, passing through each hole in the perforated steel plate 130. The perforated steel plate 130 with one or more holes serves as a single-hole or multi-hole PBL connector. For example, Figure 2 , Figure 3 and Figure 4 The diagram shows a steel-UHPC composite structure in this embodiment. It uses H-beams 100 as the steel structure. UHPC concrete layers 110 are respectively provided on the two steel plates of the H-beams 100. The steel plates of the steel structure are connected by three rows of shear studs 120 embedded in the UHPC concrete layers 110. Each row includes two shear studs 120. The steel plates of the steel structure are connected by perforated steel plates 130 embedded in the UHPC concrete layers 110. The perforated steel plates 130 have three holes. Through steel bars 140 are embedded in the UHPC concrete layers 110, passing through each hole in the perforated steel plates 130.

[0023] The calculation method for the shear bearing capacity of composite shear connectors in steel-UHPC composite structures includes the following steps: Step 1: Analyze the effect of UHPC on the shear stud bearing capacity and the mutual influence between multiple rows of shear studs. Introduce the UHPC material reinforcement coefficient and the group stud effect reinforcement coefficient to obtain the calculation formula for the shear bearing capacity of multiple rows of shear studs in UHPC. Among them, the calculation formula for the shear bearing capacity of multi-row shear studs in UHPC P u,m as follows: ; In the formula, m is the number of rows of shear studs; A st f is the cross-sectional area of ​​the shear stud. c f st These are the compressive strength of the concrete cube and the tensile strength of the shear studs, respectively; E c E s These are the elastic moduli of concrete and shear studs, respectively. The reinforcement factor of UHPC material reflects the effect of the high strength of UHPC on the bearing capacity of shear studs, and is obtained by fitting experimental data. The group-nail effect enhancement coefficient is equal to the ratio of the bearing capacity of a single nail in a multi-row shear nail system to the bearing capacity of a single nail in a single-row shear nail system, and is obtained by fitting an asymptotic function. Optional, Take 2.164.

[0024] The amplification coefficient of the clustered nail effect is calculated using the following formula. : ; In the formula, m is the number of rows of shear studs; when only one row of shear studs is set in UHPC, m is taken as 1, which is applicable to the calculation of the shear bearing capacity of a single row of shear studs in UHPC.

[0025] Step 2: Decompose the shear bearing capacity of the PBL connector into end bearing pressure, concrete tenon shear and through steel bar shear, and introduce a multi-hole reduction coefficient to reduce the bearing capacity caused by the overlap of inter-hole damage when multiple holes are arranged, so as to obtain the calculation formula of the shear bearing capacity of the PBL connector in UHPC. Among them, the shear bearing capacity of the single-hole PBL connector in UHPC The calculation formula is as follows: ; In the formula, P u Shear bearing capacity of a single-hole PBL connector in a UHPC; p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the strength enhancement factor for concrete samples; k is an undetermined coefficient, reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y This represents the yield strength of the through-steel reinforcement.

[0026] Formula for calculating the shear bearing capacity of porous PBL connectors in UHPC as follows: ; ; In the formula, p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the concrete strength enhancement coefficient; k is an undetermined coefficient reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y n represents the yield strength of the through-bar reinforcement; n is the number of holes in the PBL. This is the reduction factor for the opening.

[0027] in, It is 0.95. It is 1.06. To get 1.32, k It is 0.07.

[0028] Step 3: Linearly superimpose the shear bearing capacity calculation formula of the multi-row shear stud in UHPC with the shear bearing capacity calculation formula of PBL connector, and introduce the composite reduction effect to obtain the shear bearing capacity calculation formula of the shear stud and PBL composite connector in UHPC.

[0029] The formula for calculating the shear bearing capacity of the single-row shear stud and single-hole PBL composite connector in UHPC is as follows: ; In the formula, m 1 represents the total number of shear studs;n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f The diameter of the steel fiber; A pr The area of ​​the through-reinforcement; f pr This represents the yield strength of the through-steel reinforcement.

[0030] The formula for calculating the shear bearing capacity of multi-row shear studs and multi-hole PBL composite connectors in UHPC is as follows. ; ; In the formula, m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; h Height of the perforated steel plate; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E stThe elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; A s The cross-sectional area of ​​the through-bar; f y The yield strength of the through-bar reinforcement; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f λ is the diameter of the steel fiber; λ is the porosity reduction factor. e This is the net distance between adjacent openings in a PBL perforated plate.

[0031] in, a It is 2.94. b The value is 0.95, and c is 1.03. d It is 1.32.

[0032] The beneficial effects of the method for calculating the shear bearing capacity of composite shear connectors in steel-UHPC composite structures provided in this application embodiment are: First, by closely integrating static push-out tests, finite element numerical simulations, and theoretical analysis, the failure modes and load-slip laws are revealed through experiments, and the internal force mechanism is supplemented through finite element analysis. Based on this, the shear bearing capacity formula of composite connectors is obtained through regression analysis, forming a complete research system integrating test, simulation, and theory, which significantly improves the scientificity and reliability of the calculation formula.

[0033] Second, for the first time, the synergistic working characteristics of studs and PBL in steel-UHPC composite structures were separated from the reinforcement of UHPC material, the reinforcement of stud effect, and the reduction effect of porous structure. The material reinforcement coefficient, the reinforcement coefficient of stud effect, and the reduction coefficient of porous structure applicable to composite connectors were proposed. These methods overcome the shortcomings of traditional methods that simply superimpose or reduce individually, and accurately reflect the synergistic reinforcement and reduction laws among the components of composite connectors.

[0034] Third, the proposed formula system for calculating the shear capacity of studs, PBLs, and composite connectors is complete and clearly structured, with each component having a clearly defined physical meaning. The error between calculated and experimental values ​​is within 3%, far superior to existing standard formulas (which typically have an error exceeding 20%). Furthermore, the formulas are concise, allowing designers to quickly obtain the bearing capacity simply by substituting material and geometric parameters, significantly improving the efficiency and accuracy of shear connection design for steel-UHPC composite beams.

[0035] Fourth, the applicable scope of the calculation formula was clarified, providing clear boundary conditions for engineering design and avoiding blind application. Furthermore, based on verification using the ABAQUS finite element model, the maximum error between the calculated and experimental values ​​of the ultimate bearing capacity was only 5.8%, further ensuring the reliability of the method.

[0036] In other alternative embodiments, the steel structure in the steel-UHPC composite structure can also be I-beams, steel box girders, steel plates, steel columns, and other steel structures.

[0037] Example 1 This application provides a method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure, including the following steps: I. The following steel-UHPC composite structure specimens were prepared: like Figure 5 As shown, specimen S-0-1 is a steel-UHPC composite structure with a steel plate 130 without openings and a row (two in each row) of shear studs; S-0-1-A and S-0-1-B are two parallel specimens of specimen S-0-1. like Figure 6 As shown, specimen S-0-3 is a steel-UHPC composite structure with a steel plate of 130 without openings and three rows (two in each row) of shear studs; S-0-3-A and S-0-3-B are two parallel specimens of specimen S-0-3. like Figure 7 As shown, specimen P-1-0 is a steel-UHPC composite structure with a perforated steel plate 130, which has one hole and no shear studs; P-1-0-A and P-1-0-B are two parallel specimens of specimen P-1-0. like Figure 8 As shown, the P-3-0 specimen is a steel-UHPC composite structure with a perforated steel plate 130, which has three holes and no shear studs; P-3-0-A and P-3-0-B are two parallel specimens of the P-3-0 specimen. like Figure 9 As shown, the SP-1-3 specimen is a steel-UHPC composite structure with a perforated steel plate 130, which has one hole and three rows (two in each row) of shear studs; SP-1-3-A and SP-1-3-B are two parallel specimens of the SP-1-3 specimen.

[0038] like Figure 10 As shown, the SP-2-3 specimen is a steel-UHPC composite structure with a perforated steel plate 130, which has two holes and three rows (two per row) of shear studs; SP-2-3-A and SP-2-3-B are two parallel specimens of the SP-2-3 specimen. like Figure 11As shown, the SP-3-3 specimen is a steel-UHPC composite structure with a perforated steel plate 130, which has two holes and three rows (two in each row) of shear studs; SP-3-3-A and SP-3-3-B are two parallel specimens of the SP-3-3 specimen.

[0039] In the above specimens, the concrete slab (UHPC concrete layer 110) measures 600mm × 600mm × 150mm and is reinforced with 8mm diameter HRB400 grade structural steel bars. The H-beams (steel structure) have a cross-section of HW300mm × 300mm × 20mm × 20mm, a length of 600mm, and are made of Q355B material. The perforated steel plate 130 is made of Q355B material, measures 400mm × 100mm × 16mm, and has a perforation diameter of 50mm. The through-bar reinforcement 140 is made of HRB400 material, has a diameter of 16mm, and a length of 450mm. The shear stud 120 is of model ML15AL, with a diameter of 16mm and a height of 80mm. The hoisting reinforcement is made of HRB400 material with a diameter of 10mm.

[0040] 2. Based on the push-out test, the test values ​​of the shear bearing capacity of each specimen were obtained, and the theoretical values ​​of the shear bearing capacity of each specimen were calculated using the formula and compared. Shear bearing capacity calculation formula for multi-row shear studs in UHPC P u,m Calculate the shear capacity of the corresponding specimen: ; In the formula, m is the number of rows of shear studs; A st f is the cross-sectional area of ​​the shear stud. c f st These are the compressive strength of the concrete cube and the tensile strength of the shear studs, respectively; E c E s These are the elastic moduli of concrete and shear studs, respectively. The reinforcement factor of UHPC material reflects the effect of the high strength of UHPC on the bearing capacity of shear studs, and is obtained by fitting experimental data. The group nail effect enhancement coefficient is equal to the ratio of the bearing capacity of a single nail in a multi-row shear nail to the bearing capacity of a single nail in a single-row shear nail, and is obtained by fitting an asymptotic function. Take 2.164.

[0041] The amplification coefficient of the clustered nail effect is calculated using the following formula. : ; In the formula, m is the number of rows of shear studs.

[0042] The shear bearing capacity test values ​​of the multi-row shear nails obtained from the ejection test of the corresponding specimens were compared with the theoretical values ​​calculated by the above formula. The results are shown in Table 1. Table 1 Comparison of experimental and theoretical values ​​of shear nail ejection specimens

[0043] It can be seen that the maximum absolute value of the error does not exceed 2%, indicating that the calculation formula for the shear bearing capacity of the multi-row shear studs in this application has good fitting accuracy and engineering applicability.

[0044] Shear bearing capacity using single-hole PBL connectors in UHPC The calculation formula is used to calculate the shear capacity of the corresponding specimen: ; In the formula, P u Shear bearing capacity of a single-hole PBL connector in a UHPC; p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the strength enhancement factor for concrete samples; k is an undetermined coefficient, reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y This represents the yield strength of the through-steel reinforcement.

[0045] Shear bearing capacity calculation formula using porous PBL connectors in UHPC Calculate the shear capacity of the corresponding specimen: ; ; In the formula,p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the concrete strength enhancement coefficient; k is an undetermined coefficient reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y n represents the yield strength of the through-bar reinforcement; n is the number of holes in the PBL. This is the reduction factor for the opening.

[0046] in, It is 0.95. It is 1.06. To get 1.32, k It is 0.07.

[0047] The shear capacity test values ​​of the PBL connector obtained from the ejection test of the corresponding specimens were compared with the theoretical values ​​calculated by the above formula. The results are shown in Table 2: Table 2 Comparison of calculated and experimental values ​​of bearing capacity of PBL specimens

[0048] The comparison between theoretical and experimental values ​​is shown in Table 2. The errors are all within 3%, which meets the engineering accuracy requirements. The reduction coefficient λ of the three holes of the PBL connector is 0.467. However, it should be noted that the reduction coefficient of the PBL part in the composite connector will be affected by the presence of shear studs.

[0049] The shear capacity of the corresponding specimen was calculated using the formula for calculating the shear capacity of a single-row shear stud and single-hole PBL composite connector in UHPC: ; In the formula,m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f The diameter of the steel fiber; A pr The area of ​​the through-reinforcement; f pr This represents the yield strength of the through-steel reinforcement.

[0050] Calculate the shear capacity of the corresponding specimens using the shear capacity of multi-row shear studs and multi-hole PBL composite connectors in UHPC: ; ; In the formula, m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; h Height of the perforated steel plate; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c ,E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; A s The cross-sectional area of ​​the through-bar; f y The yield strength of the through-bar reinforcement; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f λ is the diameter of the steel fiber; λ is the porosity reduction factor. e This is the net distance between adjacent openings in a PBL perforated plate.

[0051] in, a It is 2.94. b The value is 0.95, and c is 1.03. d It is 1.32.

[0052] The test values ​​of the shear bearing capacity of the composite shear connector obtained from the ejection test of the corresponding specimens were compared with the theoretical values ​​calculated by the above formula. The results are shown in Table 3: Table 3 Comparison of theoretical and experimental values ​​for composite shear connectors

[0053] As can be seen, the maximum absolute value of the error is -2.97% (SP-3-3-A), which is still within the acceptable range for engineering. The errors of the remaining specimens are all less than 2%, and the corrected theoretical values ​​agree well with the experimental values, verifying the rationality of the proposed formula.

[0054] The detailed process and steps for calculating and analyzing the shear bearing capacity of the composite shear connector in the steel-UHPC composite structure described in the embodiments of this application for the SP-3-3 specimen (three-hole and three-row shear studs) include: (1) Determine the material parameters.

[0055] UHPC cube compressive strength f cu =126.9MPa, axial compressive strength f c =102MPa, elastic modulus E c =48.5GPa; shear nail diameter 16mm, cross-sectional area A std =201.06mm², tensile strength f std =450MPa, elastic modulus E s=206GPa; Height of the perforated steel plate h=100mm, thickness t=16mm, diameter of the perforation d p =50mm; diameter d of the through reinforcing bar s =16mm, area A pr =201.06mm², yield strength f pr =400MPa; steel fiber volume content V f =2.5%, length-to-diameter ratio is 65; number of shear stud rows m1=3, total number is 12; number of PBL holes n2=3, hole spacing e=100mm.

[0056] (2) Calculate the total shear capacity of the composite connector. According to the formula in step three of this invention:

[0057] The reduction factor for the PBL portion in the composite connector is:

[0058] Substitute the data to calculate P u,n =4735kN.

[0059] The measured value was 4880 kN, with a relative error. 2.97%, which is within the acceptable range for the project.

[0060] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure, characterized in that, Includes the following steps: The effect of UHPC on the shear stud bearing capacity and the mutual influence among multiple rows of shear studs are analyzed. By introducing the UHPC material reinforcement coefficient and the group stud effect reinforcement coefficient, the calculation formula for the shear bearing capacity of multiple rows of shear studs in UHPC is obtained. The shear capacity of PBL connectors is decomposed into end bearing pressure, concrete tenon shear and through steel reinforcement shear. A multi-hole reduction coefficient is introduced to reduce the bearing capacity caused by the overlap of damage between holes when multiple holes are arranged, so as to obtain the calculation formula of shear capacity of PBL connectors in UHPC. The shear bearing capacity calculation formula of the multi-row shear stud in the UHPC is linearly superimposed with the shear bearing capacity calculation formula of the PBL connector, and a composite reduction effect is introduced to obtain the shear bearing capacity calculation formula of the composite connector of shear stud and PBL in the UHPC.

2. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 1, characterized in that, The formula for calculating the shear bearing capacity of multi-row shear studs in the UHPC. P u,m as follows: ； In the formula, m is the number of rows of shear studs; A st f is the cross-sectional area of ​​the shear stud. c f st These are the compressive strength of the concrete cube and the tensile strength of the shear studs, respectively; E c E s These are the elastic moduli of concrete and shear studs, respectively. The reinforcement factor of UHPC material reflects the effect of the high strength of UHPC on the bearing capacity of shear studs. It is obtained by fitting experimental data and is taken as 2.

164. The group nail effect enhancement coefficient is equal to the ratio of the bearing capacity of a single nail in a multi-row shear nail to the bearing capacity of a single nail in a single-row shear nail, and is obtained by fitting an asymptotic function.

3. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 2, characterized in that, The amplification coefficient of the clustered nail effect is calculated using the following formula. : ； In the formula, m is the number of rows of shear studs.

4. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 2, characterized in that, Shear bearing capacity of single-hole PBL connectors in UHPC The calculation formula is as follows: ； In the formula, P u Shear bearing capacity of a single-hole PBL connector in a UHPC; p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the strength enhancement factor for concrete samples; k is an undetermined coefficient, reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y This represents the yield strength of the through-steel reinforcement.

5. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 2, characterized in that, Formula for calculating the shear bearing capacity of porous PBL connectors in UHPC as follows: ； ； In the formula, p e The perforated steel plate provides pressure resistance to the concrete at its end; p c For the shear resistance of the concrete tenon; p s To provide shear resistance for the perforated reinforcing bars penetrating the perforated steel plate; Increase the coefficient for end concrete; h Height of the perforated steel plate; f c The compressive strength of the concrete cube; The strength enhancement factor for concrete samples; A c The cross-sectional area of ​​the UHPC on the perforated steel plate; A s The cross-sectional area of ​​the through-bar; is the concrete strength enhancement coefficient; k is an undetermined coefficient reflecting the actual participation of the concrete tenon in the PBL connector; V f , l f , d f These are the volumetric fiber content, length, and diameter of the steel fiber, respectively. f y n represents the yield strength of the through-bar reinforcement; n is the number of holes in the PBL. This is the reduction factor for the opening.

6. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 4 or 5, characterized in that, It is 0.

95. It is 1.

06. To get 1.32, k It is 0.

07.

7. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 6, characterized in that, The formula for calculating the shear bearing capacity of a single-row shear stud and single-hole PBL composite connector in UHPC is as follows: ； In the formula, m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f The diameter of the steel fiber; A pr The area of ​​the through-reinforcement; f pr This represents the yield strength of the through-steel reinforcement.

8. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 7, characterized in that, a It is 2.

94. b The value is 0.95, and c is 1.

03. d It is 1.

32.

9. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 6, characterized in that... The formula for calculating the shear bearing capacity of multi-row shear studs and multi-hole PBL composite connectors in UHPC is as follows. ； ； In the formula, m 1 represents the total number of shear studs; n This refers to the number of holes in the PBL. a , b , c , d , k These are undetermined coefficients, reflecting the actual degree of participation of each corresponding component in the composite connector; h Height of the perforated steel plate; A st This represents the cross-sectional area of ​​the shear stud. f c , f st For the compressive strength of the concrete cube and the tensile strength of the shear studs; E c , E st The elastic modulus of concrete and shear studs; h Height of the perforated steel plate; t The thickness of the perforated steel plate; A cd The area of ​​the concrete tenon; A s The cross-sectional area of ​​the through-bar; f y The yield strength of the through-bar reinforcement; V f This refers to the volumetric content of steel fibers. l f The length of the steel fiber; d f λ is the diameter of the steel fiber; λ is the porosity reduction factor. e This is the net distance between adjacent openings in a PBL perforated plate.

10. The method for calculating the shear bearing capacity of composite shear connectors in a steel-UHPC composite structure according to claim 9, characterized in that, a It is 2.

94. b The value is 0.95, and c is 1.

03. d It is 1.32.

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