Method for calculating shear capacity of Y-shaped perforated steel plate connecting piece embedded in UHPC (Ultra High Performance Concrete)

Abstract

The invention discloses a method for calculating the shear bearing capacity of a Y-shaped perforated steel plate connecting piece embedded in UHPC (Ultra High Performance Concrete). When the shear bearing capacity of the Y-shaped perforated steel plate connecting piece is calculated, the Y-shaped perforated steel plate connecting piece is decomposed into four parts for contribution calculation: penetrating reinforcing steel bars, UHPC tenons in holes, UHPC pressure-bearing effects at the ends of steel plates and UHPC tenons between the steel plates in the same direction; when the shear bearing capacity provided by the penetrating steel bars is calculated, the influence of the shear area of the steel bars is considered; when the shear bearing capacity provided by the UHPC tenon in the hole is calculated, the influence of the UHPC shear strength and the shear angle of the steel bar is considered; when the shear bearing capacity provided by the UHPC pressure-bearing effect of the end part of the steel plate is calculated, the total pressure-bearing area influence of the end part is considered; when the shear bearing capacity provided by the UHPC tenons between the steel plates in the same direction is calculated, the influence of the width of the steel plates and the strength of the UHPC is considered; and finally, the contribution of the four parts is superposed and summed, and the shear capacity of the Y-shaped perforated steel plate connecting piece embedded in the UHPC is obtained. The method has high calculation precision, and the calculation process is simple, efficient and convenient.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel - concrete composite structures, and particularly relates to a method for calculating the shear bearing capacity of Y - shaped perforated steel plate connectors embedded in UHPC. Background Art

[0002] Steel - concrete composite beam bridges give full play to the excellent tensile performance of steel and the good compressive strength of concrete. They not only have significant economic benefits but also broad application prospects. Shear connectors, as key components to ensure the integrity and cooperative work of the concrete bridge deck and the steel beam, play an indispensable role in the structural system of steel - concrete composite beam bridges. They can bear multi - directional shear loads and effectively resist the pulling - out effect. In practical engineering applications, commonly used shear connectors include stud connectors, PBL connectors, and profiled steel connectors. Although traditional stud connectors have the advantages of simple structure and convenient construction, they have defects such as large welding workload, poor fatigue resistance, and insufficient tensile - pull bearing capacity; PBL connectors face technical bottlenecks in difficult precision control of the positioning of through - reinforcement and limited layout space in applications; profiled steel connectors generally have the risk of steel - concrete interface peeling due to insufficient interfacial bonding force. To overcome the technical limitations of existing connectors, the developed Y - shaped perforated steel plate connectors achieve performance breakthroughs through innovative structural designs: First, the Y - shaped bending structure is adopted to effectively improve the shear performance and tensile - pull capacity of the connectors; second, the UHPC tenons formed by the holes on the Y - shaped perforated steel plate can significantly enhance the integrity of the steel beam and the concrete. Numerical simulations and experimental studies have shown that the new connectors have significantly improved key performance indicators such as shear bearing capacity, pull - out performance, and fatigue life compared with traditional forms, while maintaining excellent construction operability, providing an innovative solution for the connection technology of steel - concrete composite structures.

[0003] Ultra - high - performance concrete (UHPC), with its excellent mechanical properties and durability characteristics, has become the preferred material for strengthening key parts of composite structures. However, limited by the high material cost, the traditional full - section UHPC pouring scheme has the defect of relatively high construction cost. Therefore, a Y - shaped perforated steel plate connector with local UHPC pouring is proposed, which realizes precise UHPC pouring only in the shear groove. While ensuring the shear stiffness of the interface and the connection integrity, the on - site pouring volume can be significantly reduced.

[0004] However, most of the existing calculation formulas for the shear bearing capacity of connectors are for continuously arranged PBL connectors in ordinary concrete. There is currently little research on the calculation formula for the shear bearing capacity of PBL connectors embedded in UHPC considering the concrete bearing effect. To meet the engineering requirements, it is urgent to propose a method for calculating the shear bearing capacity of Y - shaped perforated steel plate connectors embedded in UHPC. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a calculation method for the shear bearing capacity of a Y-shaped perforated steel plate connector embedded in UHPC, which is simple, efficient and convenient to calculate.

[0006] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a calculation method for the shear bearing capacity of a Y-shaped perforated steel plate connector embedded in UHPC. The Y-shaped perforated steel plate connector embedded in UHPC includes: a precast concrete slab, on which a UHPC pouring cavity is provided. Structural steel bars are arranged in the UHPC pouring cavity. A Y-shaped perforated steel plate is fixedly installed in the UHPC pouring cavity. The Y-shaped perforated steel plate includes a vertical steel plate section and a plurality of steel plate bending sections obliquely arranged on the vertical steel plate section. Adjacent two steel plate bending sections are arranged in a staggered manner so that the cross-section of the Y-shaped perforated steel plate is in a Y shape. A rectangular notch and a through hole communicating with the notch and vertically penetrating the steel plate bending section are arranged on the steel plate bending section. A through steel bar is arranged in the through hole. The notch and the through hole are filled with UHPC tenons. The through steel bar is tied and fixed with the structural steel bar. The bottom end of the Y-shaped perforated steel plate is 50 mm away from the bottom wall of the UHPC pouring cavity. The calculation method for the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC includes the following steps: S1: Calculate the shear bearing capacity provided by the through steel bars considering the shear area of the steel bars A rebar : : S2: Calculate the shear bearing capacity provided by the UHPC tenons in the openings considering the shear strength of the UHPC tenons τ c and the shear angle of the steel bars θ : : S3: Calculate the shear bearing capacity provided by the bearing action of the UHPC at the end of the steel plate considering the contact area between the end of the steel plate and the UHPC S b : : S4: Calculate the shear bearing capacity provided by the UHPC tenons between the steel plates in the same direction considering the width of the steel plate and the strength of the UHPC : S5: Calculate the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC P : In the formula, is the number of through - reinforcement bars, is the shear area of a single through - reinforcement bar, is the yield strength of the through - reinforcement bar, is the direct shear strength of UHPC, h is the length of the bent section of the steel plate, D is the diameter of the through - hole, d is the diameter of the through - reinforcement bar, b is the width of the notch, is the angle between the surface of the bent section of the steel plate and the horizontal direction, is the contact area between the end of the steel plate and UHPC, is the yield strength of the Y - shaped perforated steel plate, is the number of UHPC tenons formed between two steel plates bent in the same direction, is the width of a single bent section of the steel plate, is the compressive strength of UHPC cylinder Furthermore, in step S1, the shear area of the reinforcement bar is calculated by the following formula: In the formula, d is the diameter of the through - reinforcement bar.

[0007] Furthermore, in step S2, the shear strength of the UHPC tenon is calculated by the following formula: In the formula, is the compressive strength of the UHPC cylinder.

[0008] Furthermore, in step S3, the total bearing area at the end of the steel plate is calculated by the following formula: Wherein, is the length of the vertical section of the steel plate, is the thickness of the Y - shaped perforated steel plate.

[0009] The beneficial effects of the present invention are as follows: 1. The calculation method proposed by the present invention fills the blank of the calculation method for the shear bearing capacity of Y - shaped perforated steel plate connectors embedded in high - strength concretes such as UHPC. This method has the characteristics of high calculation accuracy, small error, simple and efficient calculation, and has strong practicability and broad application prospects.

[0010] 2. The calculation method proposed by the present invention takes into account the shear bearing capacity provided by the UHPC bearing action at the end of the steel plate, fully considers the cooperative working effect of UHPC and the steel plate, and significantly improves the calculation accuracy. It solves the problem that the existing calculation method underestimates the shear bearing capacity of the Y-shaped perforated steel plate connector, and provides a reliable theoretical basis and technical support for the engineering design of the steel-concrete composite beam bridge connector.

[0011] Other advantages, objectives and features of the present invention will be described in the following specification, and to some extent will be obvious to those skilled in the art, or those skilled in the art can obtain teachings from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following drawings for description: Figure 1 It is the calculation flow chart of the embodiment of the present invention; Figure 2 It is the schematic diagram of the shear plane of the through reinforcement in the embodiment of the present invention; Figure 3 It is the schematic diagram of the force analysis of the UHPC tenon in the opening in the embodiment of the present invention; Figure 4 It is the schematic diagram of the force-bearing area of the UHPC tenon in the opening in the embodiment of the present invention; Figure 5 It is the schematic diagram of the UHPC bearing surface at the end of the steel plate and the UHPC tenon between the steel plates in the same direction in the embodiment of the present invention; Figure 6 It is the schematic diagram of the contact surface between the end of the steel plate and UHPC in the embodiment of the present invention; Figure 7 It is the schematic diagram of the Y-shaped perforated steel plate connector embedded in UHPC in the embodiment of the present invention; Figure 8 It is the schematic diagram of the error comparison between the predicted value and the test value of the shear bearing capacity calculation in the embodiment of the present invention; Figure 9 It is the schematic diagram of the error comparison between the predicted value and the finite element simulation value of the shear bearing capacity calculation in the embodiment of the present invention.

[0013] The reference signs in the drawings are as follows: precast concrete slab 1, UHPC casting cavity 101, Y-shaped perforated steel plate 2, vertical section of steel plate 201, bent section of steel plate 202, notch 203, through hole 204, UHPC tenon 205, through reinforcement 3, and structural reinforcement 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] As Figures 1 - 9As shown in the figure, the present invention provides a method for calculating the shear bearing capacity of a Y-shaped perforated steel plate connector embedded in UHPC. Among them, the Y-shaped perforated steel plate connector embedded in UHPC is as follows Figure 7 , including: a precast concrete slab 1, on which a UHPC pouring cavity 101 is provided. Structural steel bars 4 are arranged in the UHPC pouring cavity 101. A Y-shaped perforated steel plate 2 is fixedly installed in the UHPC pouring cavity 101. The Y-shaped perforated steel plate 2 includes a steel plate vertical section 201 and a plurality of steel plate bending sections 202 obliquely arranged on the steel plate vertical section 201. Adjacent two steel plate bending sections 202 are arranged in a staggered manner so that the cross-section of the Y-shaped perforated steel plate 2 is Y-shaped. A rectangular notch 203 and a through hole 204 communicating with the notch 203 and vertically penetrating the steel plate bending section 202 are arranged on the steel plate bending section 202. A through steel bar 3 is arranged in the through hole 204. The notch 203 and the through hole 204 are filled with a UHPC tenon 205. The through steel bar 3 is tied and fixed with the structural steel bar 4. The bottom end of the Y-shaped perforated steel plate 2 is 50 mm away from the bottom wall of the UHPC pouring cavity 101.

[0015] The method for calculating the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC includes the following steps: S1: Determine the material parameters and dimension parameters; S2: Calculate the shear area of the through steel bar 3 : S3: Calculate the shear bearing capacity provided by the through steel bar 3 considering the shear area of the steel bar A rebar : S4: Calculate the shear strength of the UHPC tenon 205 : S5: Calculate the shear bearing capacity provided by the UHPC tenon in the opening considering the shear strength of the UHPC tenon τ c and the shear angle of the steel bar θ : S6: Calculate the contact area between the end of the Y-shaped perforated steel plate 2 and the UHPC : S7: Calculate considering the contact area between the end of the Y-shaped perforated steel plate 2 and the UHPC S bShear bearing capacity provided by the UHPC bearing action at the end of the Y-shaped perforated steel plate 2 : S8: Calculate the shear bearing capacity provided by the UHPC tenon between the Y-shaped perforated steel plate 2 width and the steel plates in the same direction of UHPC strength : S9: Calculate the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC : In the formula, is the number of through rebars 3, is the shear area of a single through rebar 3, is the yield strength of the through rebar 3, is the direct shear strength of UHPC, h is the length of the bent section 202 of the steel plate, D is the diameter of the through hole 204, d is the diameter of the through rebar 3, b is the width of the notch 203, is the angle between the surface of the bent section of the steel plate and the horizontal direction, is the contact area between the end of the steel plate and UHPC, is the yield strength of the Y-shaped perforated steel plate 2, is the number of UHPC tenons formed between two steel plates bent in the same direction, is the width of a single bent section 202 of the steel plate, is the compressive strength of the UHPC cylinder, is the length of the vertical section 201 of the steel plate, is the thickness of the Y-shaped perforated steel plate 2.

[0016] In this embodiment, the shear connector Standard of the Y-shaped perforated steel plate embedded in UHPC is taken as an example. As Figure 7 shown, where the width of a single bent section 202 of the steel plate is 150 mm, the thickness of the Y-shaped perforated steel plate 2 is 14 mm, the diameter of the through rebar 3 is 16 mm, the diameter of the structural rebar is 12 mm, the diameter of the through hole 204 is 40 mm, the bending angle of the bent section 202 of the steel plate is 30°, the angle between two adjacent bent sections 202 of the steel plate is 60°, the yield strength of the through rebar 3 is 366 MPa, the yield strength of the Y-shaped perforated steel plate 2 is 387 MPa, the compressive strength of the UHPC cylinder is 100.73 MPa, the length of the vertical section 201 of the steel plate is 50 mm, the length of the bent section 202 of the steel plate is 90 mm, and the number of UHPC tenons formed between two steel plates bent in the same directionm is 1; According to the above basic parameters, specimens were made for the push-out test. The Standard specimen considered the contributions of the through reinforcement, the UHPC tenons in the openings, the UHPC bearing at the ends of the steel plates, and the UHPC tenons between the steel plates in the same direction; the d0 specimen considered the contributions of the UHPC tenons in the openings, the UHPC bearing at the ends of the steel plates, and the UHPC tenons between the steel plates in the same direction; the F specimen considered the contributions of the UHPC bearing at the ends of the steel plates and the UHPC tenons between the steel plates in the same direction; the d20 specimen considered the contributions of the through reinforcement, the UHPC tenons in the openings, the UHPC bearing at the ends of the steel plates, and the UHPC tenons between the steel plates in the same direction, but the diameter of the through reinforcement was changed to 20 mm. The following results were obtained through calculation and test, as shown in Table 1. Among them is the calculated prediction value of the shear bearing capacity of the specimen, is the test value of the shear bearing capacity of the specimen obtained from the push-out test, / is the ratio of the two; Table 1 Comparison of calculated prediction values and test values: After substituting the specimen parameters into the corresponding calculation expressions, the shear bearing capacities of each specimen were obtained. By comparing and analyzing the results of the calculation method with the test results, as Figure 8 shown, it was found that the deviations all fell within the preset allowable error range, and the error between the calculated prediction value and the test value of the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC was controlled within 10%. By comparing the calculated prediction value with the finite element simulation value, as Figure 9 shown, the error was controlled within 8%. All the comparison results not only verified that the proposed calculation method and the finite element model have high accuracy and reliability, but also further confirmed the effectiveness and scientificity of this method in evaluating the shear bearing capacity of the Y-shaped perforated steel plate embedded in UHPC, indicating that this method has high accuracy and applicability in practical engineering applications.

[0017] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A calculation method for the shear bearing capacity of a Y-shaped perforated steel plate connector embedded in UHPC, characterized in that, The Y-shaped perforated steel plate connector embedded in UHPC includes: a precast concrete slab, on which a UHPC pouring cavity is provided, in which construction steel bars are arranged, and a Y-shaped perforated steel plate is fixedly installed. The Y-shaped perforated steel plate includes a vertical steel plate section and a plurality of steel plate bending sections obliquely arranged on the vertical steel plate section. Two adjacent steel plate bending sections are arranged in a staggered manner so that the cross-section of the Y-shaped perforated steel plate is Y-shaped. A rectangular notch and a through hole communicating with the notch and vertically penetrating the steel plate bending section are arranged on the steel plate bending section. A through steel bar is arranged in the through hole, and the notch and the through hole are filled with UHPC tenons. The through steel bar is fixedly bound to the construction steel bar, and the bottom end of the Y-shaped perforated steel plate is 50 mm away from the bottom wall of the UHPC pouring cavity; The calculation method for the shear bearing capacity of the Y-shaped perforated steel plate connector embedded in UHPC includes the following steps: S1: Calculate the shear bearing capacity provided by the through-going steel bars considering the shear area of the steel bars A rebar :​ S2: Calculate the shear strength of the UHPC tenon considering τ c and the shear angle of the steel bars θ to obtain the shear bearing capacity provided by the UHPC tenon in the opening : S3: Calculate the shear bearing capacity provided by the bearing action of UHPC at the end of the steel plate considering the contact area between the end of the steel plate and UHPC S b at the end of the steel plate : S4: Calculate the shear resistance provided by the UHPC tenons between steel plates in the same direction considering the width of the steel plate and the strength of the UHPC : S5: Calculate the shear bearing capacity of the Y-shaped perforated steel plate connectors embedded in UHPC P : In the formula, is the quantity of the through - reinforcement, is the shear area of a single through - reinforcement, is the yield strength of the through - reinforcement, is the direct shear strength of UHPC, h is the length of the bent section of the steel plate, D is the diameter of the through - hole, d is the diameter of the through - reinforcement, b is the width of the notch, is the angle between the surface of the bent section of the steel plate and the horizontal direction, is the contact area between the end of the steel plate and UHPC, is the yield strength of the Y - shaped perforated steel plate, is the number of UHPC tenons formed between two steel plates bent in the same direction, is the width of a single bent section of the steel plate, is the compressive strength of UHPC cylinder.

2. The shear bearing capacity calculation method of the Y-shaped perforated steel plate connector embedded in UHPC according to claim 1, characterized in that: In step S1, the shear area of the steel bar is calculated by the following formula: In the formula, d is the diameter of the through-bar.

3. The shear bearing capacity calculation method of the Y-shaped perforated steel plate connector embedded in UHPC according to claim 2, characterized in that: In step S2, the shear strength of the UHPC tenon is calculated by the following formula: In the formula, is the compressive strength of the UHPC cylinder.

4. The shear bearing capacity calculation method of the Y-shaped perforated steel plate connector embedded in UHPC according to claim 3, characterized in that: In step S3, the total bearing area at the end of the steel plate is calculated by the following formula: Among them, is the length of the vertical section of the steel plate, is the thickness of the Y-shaped perforated steel plate.

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