One-way slidable shear connector based on triangular limiting structure and construction method thereof

Abstract

The present invention relates to a one-way sliding shear connector based on a triangular limiting structure, which is used for connecting a steel beam and a concrete slab in a composite beam structure. The one-way sliding shear connector includes an inclined steel plate and a vertical steel plate, and the inclined steel plate and the vertical steel plate form a triangular shear key; the inclined steel plate is the oblique side of the triangular shear key, which is used to assist the steel beam in sliding outward, and the vertical steel plate is the vertical side of the triangular shear key, which is used to ensure that the steel beam and the concrete slab are fixed inward. The shear connector has a simple structure, low cost, and convenient construction. It utilizes the sliding effect of the inclined steel plate and the limiting effect of the vertical steel plate to achieve one-way sliding in the negative bending moment zone, which can release the constraint between the steel beam and the concrete slab, effectively avoid the tensile stress caused by the coordinated deformation of the concrete slab and the steel beam, improve the durability of the structure, and effectively avoid the waste of prestress in the concrete slab, reducing the engineering workload of prestress construction.

Description

Technical Field

[0001] The present invention relates to the technical field of structural engineering, and in particular to a unidirectional slidable shear connector based on a triangular limiting structure and a construction method thereof. Background Art

[0002] Steel-concrete composite structure is a new type of structure developed on the basis of steel structure and reinforced concrete structure. Compared with reinforced concrete structure, it has many advantages such as light weight, strong seismic resistance, and small cross-sectional size. Compared with steel structure, it can reduce the amount of steel used, increase stiffness, increase stability and integrity, enhance structural fire resistance and durability, etc. It has the advantages of both steel structure and reinforced concrete structure, has significant technical, economic and social benefits, is suitable for the national conditions of my country's infrastructure construction, and has been increasingly widely used in urban overpasses and building structures in my country, and is developing towards large spans.

[0003] Steel-concrete composite structures primarily utilize shear connectors (studs, channels, and bent bars) between the steel beam and concrete flange to resist uplift and relative slippage at the interface, allowing them to function as a single unit. Shear connectors have two primary functions: shear resistance, which transfers shear forces between the steel beam and the concrete slab, ensuring they deform in tandem, share the load, and maximize the performance of the composite material. They also provide pullout resistance, anchoring the concrete slab to the upper edge of the steel beam to prevent separation during bending, ensuring the two materials function together.

[0004] When a continuous beam bridge is subjected to stress, the mid-span area is generally subjected to positive bending moments, while the area near the supports is generally subjected to larger negative bending moments. Under the action of traditional shear keys, the concrete slab and steel beam are firmly connected and work together. In the positive bending moment area, the concrete slab is in compression, and the steel beam is in tension, which is in line with the stress characteristics of the two materials. In the negative bending moment area, an overly strong connection will cause the concrete slab and steel beam to be in tension. Long-term tensile stress will lead to serious durability problems for the concrete slab, which is undesirable in engineering. At the same time, in traditional designs, it is often necessary to add a certain amount of prestress to the concrete to prevent cracking of the concrete. The combined deformation of the steel beam and concrete slab in the negative bending moment area will cause a large part of the prestress to be transferred to the steel beam, reducing the degree of prestress introduction into the concrete and resulting in prestress waste. Summary of the Invention

[0005] In order to solve the problem that the shear key connection in the negative bending moment zone of the composite beam is too firm, the present invention provides a one-way sliding shear connector based on a triangular limiting structure, and proposes a construction method for the one-way sliding shear connector based on a triangular limiting structure for such a component.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a one-way sliding shear connector based on a triangular limiting structure, which is used for connecting a steel beam and a concrete slab in a composite beam structure. The one-way sliding shear connector includes an inclined steel plate and a vertical steel plate, and the inclined steel plate and the vertical steel plate form a triangular shear key; the inclined steel plate is the hypotenuse of the triangular shear key, which is used to assist the steel beam to slide outward, and the vertical steel plate is the vertical side of the triangular shear key, which is used to ensure that the steel beam and the concrete slab are fixed inward.

[0008] Among them, triangular shear keys are symmetrically installed on the steel beam with the maximum bending moment of the steel beam as the center.

[0009] In one embodiment of the present invention, the vertical steel plate and the inclined steel plate are connected to the upper edge of the steel beam by welding.

[0010] In one embodiment of the present invention, the lower edge of the vertical steel plate is welded to the upper edge of the steel beam, the upper edge of the inclined steel plate is welded to the upper edge of the vertical steel plate, and the lower edge of the inclined steel plate is welded to the upper edge of the steel beam.

[0011] In the present invention, the inclined steel plate forms a desired angle with the upper edge of the steel beam and is welded to the vertical steel plate in a triangular shape to form a triangular shear key. The triangular shear key is made of steel plates spliced together and arranged symmetrically along the maximum bending moment point.

[0012] In one embodiment of the present invention, the angle between the inclined steel plate and the upper edge of the steel beam is 20°<α≤45°, and the height of the vertical steel plate is 15 cm<h≤25 cm.

[0013] In one embodiment of the present invention, the one-way slidable shear connector is anchored in the concrete slab.

[0014] In one embodiment of the present invention, the size, quantity and range of the one-way slidable shear connector can be flexibly adjusted according to design requirements, and can also be used together with other forms of shear connectors.

[0015] In one embodiment of the present invention, the concrete slab comprises concrete, steel bars and prestressed steel tendons.

[0016] The present invention further provides a construction method of a unidirectional slidable shear connector based on a triangular limiting structure, comprising the following steps:

[0017] Step S1: Calculate the pull-out strength and shear strength according to the structural design requirements, and determine the layout range and number of shear keys;

[0018] Step S2: Weld the vertical steel plate perpendicularly to the upper edge of the steel beam to locate the shear key, then weld the upper edge of the inclined steel plate to the upper edge of the vertical steel plate, and weld the lower edge of the inclined steel plate to the steel beam to form a triangular shear key system with right-angled sides on both sides facing the fulcrum;

[0019] Step S3: Cast a concrete slab above the steel beam to which the shear keys are welded, so that the steel beam and the concrete slab work together under the connection of the shear keys.

[0020] In one embodiment of the present invention, in step S1, the number and range of required shear keys should be calculated in detail according to the design requirements. The present invention only stipulates the shape, size and welding method of the shear keys. The specific number and arrangement should be adjusted according to the structural requirements.

[0021] In one embodiment of the present invention, the angle between the inclined steel plate and the upper edge of the steel beam in step S2 is 20°<α≤45°, and the height of the vertical steel plate is 15cm<h≤25cm. The specific dimensions should be adjusted according to structural requirements.

[0022] In one embodiment of the present invention, in step S2, the triangular shear keys and ordinary shear studs may be mixed and welded on the steel beam in a certain quantity ratio in combination with the design requirements of the actual structure.

[0023] In one embodiment of the present invention, the height of the triangular shear key should be slightly smaller than the height of an ordinary shear stud.

[0024] During the sliding of the concrete slab, ordinary shear nails are taller and more flexible, so the shear force they can provide is smaller. Therefore, ordinary shear nails can strengthen the pull-out resistance of the triangular shear key while ensuring unidirectional sliding. In addition, the stiffness of ordinary shear nails can be increased according to design requirements, so that the shear force between the steel beam and the concrete slab will not be completely released during unidirectional sliding, thereby realizing precise control of the unidirectional shear capacity of the composite beam structure.

[0025] In one embodiment of the present invention, the triangular shear keys in step S2 should be arranged symmetrically along the maximum bending moment point of the steel beam.

[0026] In one embodiment of the present invention, when only one side of the steel beam structure needs to release shear force in step S2, the vertical steel plate should be close to the maximum reverse bending moment point, and the inclined steel plate should be away from the maximum reverse bending moment point.

[0027] The unidirectional slidable shear connector based on the triangular limiting structure provided by the present invention utilizes the sliding action of the inclined surface and the limiting action of the vertical surface to realize the unidirectional release of the constraint between the steel beam and the concrete slab. In the positive bending moment area, the steel beam and the concrete slab are closely dependent on each other under the action of the vertical steel plate of the shear key, which limits the relative displacement between the two, so that they can synergistically deform and work together under the action of the positive bending moment, giving full play to the advantages of the composite material; in the negative bending moment area, the steel beam has a tendency to slide outward at the steel-concrete interface, and can be completely separated from the concrete slab by the inclined surface of the shear key to realize the release of shear force, which can not only prevent the concrete slab from bearing tensile stress due to synergistic deformation, but also allow the prestress to be fully introduced into the concrete slab, thereby minimizing the waste of prestress and reducing the engineering workload of prestress construction.

[0028] The shear connector has a simple structure, low cost and easy construction. It uses the sliding effect of the inclined steel plate and the limiting effect of the vertical steel plate to achieve unidirectional sliding in the negative bending moment area, which can release the constraints between the steel beam and the concrete slab, effectively avoiding the tensile stress caused by the coordinated deformation of the concrete slab and the steel beam, and improving the durability of the structure. At the same time, it effectively avoids the waste of prestress in the concrete slab and reduces the workload of prestressed construction.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1) The present invention has a simple structure and is easy to construct. It utilizes the sliding and limiting effect of the triangular shear key to achieve unidirectional release of shear force in the negative bending moment zone, and realizes automatic control of shear force at the interface of the steel-concrete composite beam structure.

[0031] 2) The present invention is highly flexible and adaptable, and the size, quantity, and arrangement range of the shear keys can be freely adjusted according to structural design requirements;

[0032] 3) This invention can be used in conjunction with other types of shear keys (shear studs), ensuring that the shear force in the negative moment zone is not completely zero when slip occurs. By adjusting the number, size, ratio, and arrangement of the triangular shear keys and other types of shear keys, the shear and pullout resistance of the composite beam can be freely controlled.

[0033] Additional aspects and advantages of the present invention will be given in part in the following description or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The bending moment diagram for the steel-concrete composite continuous beam bridge;

[0035] Figure 2 This is a schematic diagram of the arrangement of common shear studs;

[0036] Figure 3This is a schematic structural diagram of Example 1 of the present invention;

[0037] Figure 4 This is the layout diagram of the shear connectors of the steel-concrete composite continuous beam bridge;

[0038] Figure 5 This is a structural diagram of Example 2 of the present invention.

[0039] Figure 6 This is a structural diagram of Example 3 of the present invention.

[0040] Figure 7 A structural deformation diagram of an embodiment of the present invention;

[0041] The numbers in the figure are as follows: 1—inclined steel plate, 2—vertical steel plate, 3—concrete plate, 4—steel beam, 5—ordinary shear studs. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0045] In the present invention, unless otherwise specified or limited, the terms "connected" and "fixed" should be understood in a broad sense. For example, "fixed" can mean fixed connection, detachable connection, or integration; it can mean direct connection or indirect connection through an intermediate medium, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0046] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0047] Figure 1 is the bending moment diagram of the steel-concrete composite continuous beam bridge, Figure 2 The following embodiments of the present invention use a structure different from that of an ordinary steel-concrete composite continuous beam bridge.

[0048] Example 1

[0049] In this embodiment, only three rows of triangular shear keys are installed on the top of the steel beam, and no shear nails are installed.

[0050] The method of connecting composite beams by using a unidirectional slidable shear connector based on a triangular limiting structure includes the following steps:

[0051] (1) According to the requirements of Example 1, calculate and determine the layout range and number of the triangular shear keys. Specifically, the number and layout of the shear keys should be adjusted according to structural requirements;

[0052] (2) The lower edge of the vertical steel plate 2 is welded to the upper edge of the steel beam 4 to determine the position of the shear key. In the negative bending moment area, Figure 4 As shown in Figure 2, the triangular shear keys are installed symmetrically with the maximum bending moment as the center. In the positive bending moment area, as shown in Figure 2 Figure 4 As shown, with the maximum bending moment as the center, triangular shear keys are installed symmetrically. Specifically, according to the designed angle, the upper edge of the inclined steel plate 1 is welded to the upper edge of the vertical steel plate 2, and the lower edge of the inclined steel plate 1 is welded to the upper edge of the steel beam 4, as shown in FIG. Figure 3 As shown;

[0053] (3) After the shear keys are welded, the concrete slab 3 is cast to achieve the connection and anchoring between the steel and the concrete;

[0054] (4) This embodiment utilizes a unidirectional sliding shear connector based on a triangular limiting structure to achieve unidirectional sliding of the steel-concrete composite beam and unidirectional release of shear force. Specifically, Figure 6 As shown in the figure, in the positive bending moment region, due to the downward bending of the main beam, the lower edge of the concrete slab 3 extends and the upper edge of the steel beam 4 contracts. At the steel-concrete connection interface, the steel beam 4 tends to slide relative to the concrete slab 3 in the direction of the maximum bending moment. However, due to the limiting effect of the vertical steel plate 2, relative slip cannot occur. The steel beam and the concrete slab are constrained by the shear key and deform in coordination, working together.

[0055] In the negative bending moment area, due to the upward bending of the main beam, the lower edge of the concrete slab 3 shrinks and the upper edge of the steel beam 4 extends. At the steel-concrete connection interface, the steel beam 4 tends to slide away from the direction of the maximum bending moment relative to the concrete slab 3. Under the action of the inclined steel plate 1, the steel beam 4 can slide freely, and the deformation of the steel beam will not cause the deformation of the concrete slab, thereby releasing the combined effect of the two.

[0056] Effect evaluation:

[0057] In this embodiment, only the triangular shear connector is used. In the positive bending moment region, due to the limiting effect of the vertical baffle 1, the steel beam and the concrete slab are tightly anchored, enabling their coordinated deformation. In the negative bending moment region, the steel beam and the concrete slab can slide freely, and the combined effect of the two completely disappears, achieving a complete unidirectional release of the shear force.

[0058] Example 2

[0059] In this embodiment, two rows of triangular shear keys and one row of ordinary shear studs are installed on the top of the steel beam.

[0060] The method of connecting composite beams by using a unidirectional slidable shear connector based on a triangular limiting structure includes the following steps:

[0061] (1) According to the requirements of Example 2, the arrangement range and number of the triangular shear keys and ordinary shear studs are calculated and determined. Specifically, the specific size of the shear keys and the ratio of the two shear keys should be adjusted according to the structural requirements. The height of the triangular shear keys should be slightly smaller than the height of the ordinary shear studs.

[0062] (2) Welding the common shear studs 5 at the designated position on the upper edge of the steel beam 4;

[0063] (3) The lower edge of the vertical steel plate 2 is welded to the upper edge of the steel beam 4 to determine the position of the shear key. In the negative bending moment area, Figure 4 As shown in Figure 2, the triangular shear keys are installed symmetrically with the maximum bending moment as the center. In the positive bending moment area, as shown in Figure 2 Figure 4 As shown, with the maximum bending moment as the center, triangular shear keys are installed symmetrically. Specifically, according to the designed angle, the upper edge of the inclined steel plate 1 is welded to the upper edge of the vertical steel plate 2, and the lower edge of the inclined steel plate 1 is welded to the upper edge of the steel beam 4. The structure after welding the ordinary shear studs 5 and the triangular shear keys is as shown. Figure 5 As shown;

[0064] (4) After the shear keys are welded, the concrete slab 3 is cast to achieve the connection and anchoring between the steel and the concrete;

[0065] (5) This embodiment utilizes a unidirectional sliding shear connector based on a triangular limiting structure to achieve unidirectional sliding of the steel-concrete composite beam and unidirectional release of shear force. Specifically, in the positive bending moment zone, due to the downward bending of the main beam, the lower edge of the concrete slab 3 extends and the upper edge of the steel beam 4 contracts. At the steel-concrete connection interface, the steel beam 4 tends to slide relative to the concrete slab 3 in the direction of the maximum bending moment. Due to the limiting effect of the vertical steel plate 2, relative sliding cannot occur. The steel beam and the concrete slab are constrained by the shear key to cooperate in deformation and work together.

[0066] In the negative bending moment area, due to the upward bending of the main beam, the lower edge of the concrete slab 3 shrinks and the upper edge of the steel beam 4 extends. At the steel-concrete connection interface, the steel beam 4 tends to slide away from the direction of the maximum bending moment relative to the concrete slab 3. Under the action of the inclined steel plate 1, the steel beam 4 can slide freely, but due to the influence of the ordinary shear nails 5, a certain shear force still remains between the steel beam and the concrete slab, and incomplete coordinated deformation can still be achieved. Therefore, in Example 2, due to the addition of the ordinary shear nails 5, the combined action of the steel beam 4 and the concrete slab 3 is only partially released according to design requirements.

[0067] Effect evaluation:

[0068] In this embodiment, the triangular shear connector and the ordinary shear nail are used at the same time. In the positive bending moment area, due to the limiting effect of the vertical baffle 1, the steel beam and the concrete slab are tightly anchored, and the coordinated deformation of the two can be achieved; in the negative bending moment area, under the sliding effect of the inclined steel plate 1, the constraint between the steel beam 4 and the concrete slab 3 is partially released, but due to the presence of the ordinary shear nail 5, a certain shear force still exists between the two, and the combined effect does not completely disappear. The combination ratio of the two shear keys can be freely adjusted according to design requirements to achieve precise control of the shear force in the negative bending moment area.

[0069] The ordinary shear nails 5 have a higher height and greater flexibility, and thus exhibit a more obvious pull-out resistance. Therefore, the use of the ordinary shear nails can enhance the pull-out resistance of the triangular limit shear key and prevent the steel beam and the concrete slab from separating during bending.

[0070] Example 3

[0071] In this embodiment, two rows of triangular shear keys are unidirectionally installed on the top of the steel beam.

[0072] The method of connecting composite beams by using a unidirectional slidable shear connector based on a triangular limiting structure includes the following steps:

[0073] (1) According to the requirements of Example 3, calculate and determine the layout range and number of the triangular shear keys. Specifically, the number and layout of the shear keys should be adjusted according to structural requirements;

[0074] (2) The lower edge of the vertical steel plate 2 is welded to the upper edge of the steel beam 4 to determine the position of the shear key. In the negative bending moment area, Figure 6 As shown, the vertical steel plate is oriented toward the maximum bending moment point and triangular shear keys are installed. Figure 4 As shown, the triangular shear keys are symmetrically installed with the maximum bending moment as the center. Specifically, according to the designed angle, the upper edge of the inclined steel plate 1 is welded to the upper edge of the vertical steel plate 2, and the lower edge of the inclined steel plate 1 is welded to the upper edge of the steel beam 4;

[0075] (3) After the shear keys are welded, the concrete slab 3 is cast to achieve the connection and anchoring between the steel and the concrete;

[0076] (4) This embodiment utilizes a unidirectional sliding shear connector based on a triangular limiting structure to achieve unidirectional sliding of the steel-concrete composite beam and unidirectional release of shear force. Specifically, Figure 7 As shown in the figure, in the positive bending moment region, due to the downward bending of the main beam, the lower edge of the concrete slab 3 extends and the upper edge of the steel beam 4 contracts. At the steel-concrete connection interface, the steel beam 4 tends to slide relative to the concrete slab 3 in the direction of the maximum bending moment. However, due to the limiting effect of the vertical steel plate 2, relative slip cannot occur. The steel beam and the concrete slab are constrained by the shear key and deform in coordination, working together.

[0077] In the negative bending moment area, due to the upward bending of the main beam, the lower edge of the concrete slab 3 shrinks and the upper edge of the steel beam 4 extends. At the steel-concrete connection interface, the steel beam 4 tends to slide away from the direction of the maximum bending moment relative to the concrete slab 3. Under the action of the inclined steel plate 1, the steel beam 4 can slide freely, and the deformation of the steel beam will not cause the deformation of the concrete slab, thereby releasing the combined effect of the two.

[0078] Effect evaluation:

[0079] In this embodiment, only the triangular shear connector is used. In the positive bending moment region, due to the limiting effect of the vertical baffle 1, the steel beam and the concrete slab are tightly anchored, enabling their coordinated deformation. In the negative bending moment region, the steel beam and the concrete slab can slide freely, and the combined effect of the two completely disappears, achieving complete release of the unilateral shear force.

[0080] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A construction method for a one-way slidable shear connector based on a triangular limiting structure, characterized in that: A one-way slidable shear connector based on a triangular limiting structure is used for connecting a steel beam (4) and a concrete slab (3) in a composite beam structure, wherein the one-way slidable shear connector comprises an inclined steel plate (1) and a vertical steel plate (2), wherein the inclined steel plate (1) and the vertical steel plate (2) form a triangular shear key; the inclined steel plate (1) is the oblique side of the triangular shear key, and is used to assist the steel beam (4) in sliding outward, and the vertical steel plate (2) is the vertical side of the triangular shear key, and is used to ensure that the steel beam (4) and the concrete slab (3) are fixed inward; The vertical steel plate (2) and the inclined steel plate (1) are connected to the upper edge of the steel beam (4) by welding; the lower edge of the vertical steel plate (2) is welded to the upper edge of the steel beam (4), the upper edge of the inclined steel plate (1) is welded to the upper edge of the vertical steel plate (2), and the lower edge of the inclined steel plate (1) is welded to the upper edge of the steel beam (4); The construction method includes the following steps: Step S1: Calculate the pull-out strength and shear strength according to the structural design requirements, and determine the layout range and number of shear keys; Step S2, vertically welding the vertical steel plate (2) to the upper edge of the steel beam (4) to position the shear key, then welding the upper edge of the inclined steel plate (1) to the upper edge of the vertical steel plate (2), and welding the lower edge of the inclined steel plate (1) to the steel beam (4), to form a triangular shear key system with right-angled sides on both sides facing the fulcrum; Step S3: Casting a concrete slab (3) above the steel beam (4) to which the shear key is welded, so that the steel beam (4) and the concrete slab (3) work together under the connection action of the shear key.

2. The construction method of the one-way slidable shear connector based on the triangular limiting structure according to claim 1 is characterized in that: With the maximum bending moment of the steel beam (4) as the center, triangular shear keys are symmetrically installed on the steel beam (4).

3. The construction method of the one-way slidable shear connector based on the triangular limiting structure according to claim 1 is characterized in that: The one-way slidable shear connector is anchored in the concrete slab (3).

4. The construction method of the one-way slidable shear connector based on the triangular limiting structure according to claim 1 is characterized in that: In step S2, the angle between the inclined steel plate (1) and the upper edge of the steel beam (4) is 20°<α ≤ 45°, and the height of the vertical steel plate (2) is 15 cm<h ≤ 25 cm.

5. The construction method of the one-way slidable shear connector based on the triangular limiting structure according to claim 1 is characterized in that: In step S2, the triangular shear keys and the common shear studs (5) are mixed and welded on the steel beam (4) according to a certain quantity ratio.

6. The construction method of the one-way slidable shear connector based on the triangular limiting structure according to claim 1 is characterized in that: In step S2, when only one side of the steel beam (4) structure needs to release shear force, the vertical steel plate (2) is close to the maximum reverse bending moment point, and the inclined steel plate (1) is away from the maximum reverse bending moment point.

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