Wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method

Abstract

This invention discloses a wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method, relating to the field of civil engineering structural technology. It includes a steel beam and a precast concrete layer. Several pre-embedded cavities are formed in the precast concrete layer, and each cavity contains a set of shear connection components for connecting to the steel beam. Several sets of receiving components are provided at the upper flange of the steel beam, and these components are interlocked with the shear connection components. Both the shear connection components and the receiving components are tightly connected by fastening components. This invention, using the aforementioned wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method, allows for complete and non-destructive separation of the steel beam from the precast concrete layer simply by removing the high-strength bolts at the bottom. The entire process requires no demolition of the main structural components, greatly improving the green recycling rate and construction convenience of prefabricated buildings.

Description

Technical Field

[0001] This invention relates to the field of civil engineering structural technology, and in particular to a wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method. Background Technology

[0002] In traditional steel-concrete composite beam structure design, welded studs are typically used as shear connectors. When the composite beam is under load, horizontal shear force is primarily transferred by studs welded to the upper flange of the steel beam and embedded in the concrete slab, thus ensuring that the steel beam and the concrete slab work together. However, this traditional connection and force transfer method has the following significant drawbacks: (1) The components are not detachable and the recycling cost is high: Traditional welded studs are directly welded to the steel beam at one end and firmly cast into the concrete at the other end. This "dead knot" connection is an irreversible structure. When the building reaches the end of its service life or needs to be demolished due to changes in function, the steel beam and the concrete slab cannot be separated without damage. In engineering, the steel beam is often cut by gas cutting or the concrete is forcibly demolished, resulting in the high-value steel structure being unable to be reused and generating a large amount of construction waste. This completely violates the development trend of modern buildings that are "green and low-carbon" and "recyclable components".

[0003] (2) The stress mechanism is unreasonable and prone to shear failure: When traditional welded studs or ordinary cylindrical detachable bolts bear the huge horizontal shear force at the interface of the composite beam, the rod is directly in a pure shear state. Under long-term alternating loads or rare earthquakes, the root of the slender rod is prone to severe stress concentration, leading to fatigue cracking or even direct shearing. At the same time, due to the small contact area between ordinary studs and concrete, the local concrete is prone to crushing and splitting failure at the moment of stress, which seriously threatens the overall safety of the composite beam.

[0004] (3) Limited construction interface and difficulty in maintaining hidden damage: Although some bolt-connected detachable nodes have appeared on the market, most of them require a large operating hole to be reserved above the precast concrete slab so that bolts can be screwed in from above. This not only requires a lot of secondary grouting work in the later stage, which damages the flatness and overall stress integrity of the precast floor slab, but also makes it difficult for maintenance personnel to inspect or replace the components independently once hidden damage occurs.

[0005] Therefore, there is an urgent need in this field for a new type of fully detachable steel-concrete composite beam shear connection node that can change the traditional shear force transmission mechanism of studs, transform shear force into compressive force by changing the geometry of the contact surface to protect the fasteners, and achieve 100% non-destructive separation and rapid recycling of the steel structure and the precast concrete layer without damaging the main structure. Summary of the Invention

[0006] The purpose of this invention is to provide a wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method, which solves the problems of non-detachable shear components, unreasonable stress mechanism, easy shear failure, and limited construction interface in the existing technology of traditional steel-concrete composite beams.

[0007] To achieve the above objectives, the present invention provides a wedge-shaped self-locking detachable steel-concrete composite beam shear connection node, including a steel beam and a precast concrete layer. The precast concrete layer has a plurality of pre-embedded molding cavities, and each pre-embedded molding cavity is provided with a set of shear connection components, which are used to connect with the steel beam. Several sets of supporting components are provided at the upper flange of the steel beam. The supporting components are fitted and connected with the shear-resistant connecting components, and both the shear-resistant connecting components and the supporting components are connected by fastening components through and pressing them together.

[0008] Preferably, the receiving component includes a plurality of reserved holes formed on the upper flange, and a shear-resistant groove is formed downward around the reserved holes at the top surface of the upper flange.

[0009] Preferably, the shear-resistant connection assembly includes a shear-resistant connector embedded in the pre-embedded molding cavity, the shear-resistant connector being configured as an inverted frustum-shaped wedge structure, and the outer surface of the shear-resistant connector being coated with an isolation medium.

[0010] Preferably, the bottom surface of the shear connector protrudes beyond the bottom surface of the precast concrete layer, and the bottom surface of the shear connector is provided with a shear protrusion, which is fitted and connected to the shear groove. The shear connector has an internally threaded blind hole at its internal center along the vertical direction, and the internally threaded blind hole is connected to the fastening assembly.

[0011] Preferably, the fastening assembly includes a high-strength bolt and a flat washer. The flat washer is disposed on the bottom surface of the upper flange and located outside the reserved hole. The high-strength bolt passes through the flat washer, the reserved hole and the internal thread blind hole from bottom to top in sequence and is connected by threads.

[0012] Preferably, the vertical depth of the internal threaded blind hole is greater than the effective thread length of the high-strength bolt screwed into the shear-resistant connector.

[0013] Preferably, a cavity is provided between the top of the internally threaded blind hole and the top of the high-strength bolt.

[0014] Preferably, the diameter of the reserved hole is larger than the diameter of the portion through which the high-strength bolt passes, in order to reserve a gap for engineering installation.

[0015] Preferably, the reserved holes and the shear-resistant connectors are arranged in a double-row symmetrical structure that avoids the web of the steel beam.

[0016] A method for shear connection of wedge-shaped self-locking detachable steel-concrete composite beams includes the following steps: S1. Factory Prefabrication Stage: During the production of the precast concrete layer, the shear connector is fixed upside down in the template according to the designed hole position, and the outer surface is coated with an isolation and release medium. After the concrete is poured and cured, the shear connector is permanently embedded in the concrete, forming a naturally fitting reserved cavity. S2. On-site assembly stage: The precast concrete layer with its own shear-resistant connectors at the bottom is lowered onto the steel beam using lifting equipment, so that the shear-resistant protrusions fall precisely into the shear-resistant grooves to achieve preliminary mechanical positioning. S3, Bottom-mounted fastening stage: From below the steel beam, the construction personnel pass the high-strength bolts through the flat washers and reserved holes from bottom to top, then screw them into the internal thread blind holes, and apply pre-tightening force with a torque wrench to complete the dry assembly.

[0017] Therefore, the present invention, employing the above-mentioned wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method, has the following beneficial effects: (1) The shear groove of this connection node is arranged in a double row symmetrical arrangement to avoid the web of the steel beam, which provides sufficient clearance for the fastening construction at the bottom of the component.

[0018] (2) The shear connector in this connection node is provided with shear protrusions, which directly bear most of the horizontal shear force through physical mechanical interlocking, thereby protecting the internal fasteners from direct shear damage.

[0019] (3) The precast concrete layer in this connection node is provided with a pre-embedded molding cavity. When it encounters external horizontal shear force, the cavity wall of the pre-embedded molding cavity and the inclined surface of the wedge connector will squeeze each other, generating a strong geometric self-locking effect, which will convert part of the horizontal shear force into normal extrusion force and effectively prevent local splitting of the concrete.

[0020] (4) The fastening components in this connection node transfer all the complex assembly and disassembly operations to below the interface. After the earthquake or when the building reaches the end of its service life, the axial constraint can be released by simply removing the high-strength bolts from the bottom. The steel beam and precast components can be 100% disassembled and independently recycled without breaking the main concrete.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of the wedge-shaped self-locking detachable steel-concrete composite beam shear connection node of the present invention; Figure 2This is a cross-sectional view of the wedge-shaped self-locking detachable steel-concrete composite beam shear connection node of the present invention; Figure 3 This is an exploded structural diagram of the wedge-shaped self-locking detachable steel-concrete composite beam shear connection node of the present invention; Figure 4 This is a schematic diagram of the shear connection component of the wedge-shaped self-locking detachable steel-concrete composite beam shear connection node of the present invention. Reference numerals: 100, steel beam; 110, upper flange; 111, reserved hole; 112, shear groove; 200, precast concrete layer; 210, embedded forming cavity; 310, shear connector; 312, shear protrusion; 313, internal thread blind hole; 320, high-strength bolt; 322, flat washer. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] Example Please see Figures 1-4 The present invention provides a wedge-shaped self-locking detachable steel-concrete composite beam shear connection node, including a steel beam 100 and a precast concrete layer 200. The precast concrete layer 200 has a plurality of pre-embedded molding cavities 210, and each pre-embedded molding cavity 210 is provided with a set of shear connection components, which are used to connect with the steel beam 100.

[0026] The steel beam 100 provides basic support, and several sets of receiving components are provided at its upper flange 110. The receiving components include several reserved holes 111 on the upper flange 110. At the top surface of the upper flange 110, shear grooves 112 are formed downward around the reserved holes 111. The shear grooves 112 are arranged in two rows symmetrically, avoiding the web of the steel beam 100, providing sufficient clearance for the fastening construction at the bottom of the component. The receiving components and the shear connection components are interlocked and connected, and both the shear connection components and the receiving components are connected and pressed together by fastening components.

[0027] The shear connection assembly includes a shear connector 310 embedded in the pre-embedded molding cavity 210. The shear connector 310 is a core force transmission component set between the steel beam 100 and the concrete layer. When subjected to external horizontal shear force, the cavity wall of the pre-embedded molding cavity 210 and the wedge-shaped inclined surface of the shear connector 310 are mutually squeezed, generating a strong geometric self-locking effect, which converts part of the horizontal shear force into normal compressive force, effectively preventing local splitting of the concrete.

[0028] In this embodiment, the shear connector 310 is configured as an inverted frustum-shaped wedge structure. Besides the inverted frustum-shaped structure, other geometric shapes such as an inverted polygonal frustum, with a larger top and smaller bottom, can also be used. The outer surface of the shear connector 310 is coated with an insulating medium. The bottom surface of the shear connector 310 protrudes from the bottom surface of the precast concrete layer 200, and a shear protrusion 312 is provided on the bottom surface of the shear connector 310. The shear protrusion 312 is fitted into the shear groove 112. An internally threaded blind hole 313 is vertically formed at the center of the shear connector 310, and the internally threaded blind hole 313 is connected to the fastening assembly.

[0029] The fastening assembly includes a high-strength bolt 320 and a flat washer 322. The flat washer 322 is disposed on the bottom surface of the upper flange 110 and located outside the pre-drilled hole 111. The high-strength bolt 320 passes through the flat washer 322, the pre-drilled hole 111, and the internally threaded blind hole 313 sequentially from bottom to top, and is threadedly connected. The high-strength bolt 320 is used to compress the flat washer 322, so that the shear connector 310 is tightly pressed onto the steel beam 100 to provide a stable preload. The fastening assembly is used to pull the shear connector 310 downward, so that under the action of earthquake or external load, the shear connector 310 can generate a self-locking compressive force through the wedge-shaped inclined surface and the cavity wall of the pre-embedded forming cavity 210, and bear the horizontal shear force through the mechanical engagement of the shear protrusion 312 and the shear groove 112, protecting the high-strength bolt 320 from direct shear damage.

[0030] The vertical depth of the internally threaded blind hole 313 is greater than the effective thread length of the high-strength bolt 320 when screwed into the shear-resistant connector 310. A clearance cavity (e.g., a 3mm gap) is provided between the top of the internally threaded blind hole 313 and the top of the high-strength bolt 320 to ensure that the top of the high-strength bolt 320 does not rigidly abut against the bottom of the reserved hole 111 during the tightening process, thereby ensuring that the applied torque can be completely converted into a downward pull-out preload.

[0031] The diameter of the reserved hole 111 is larger than the diameter of the portion through which the high-strength bolt 320 passes, and is used to reserve a clearance for engineering installation. The reserved hole 111 and the shear connector 310 adopt a double-row symmetrical arrangement structure that avoids the web of the steel beam 100. This structural arrangement makes the structural stress more balanced; on the other hand, it provides sufficient clearance for the construction personnel at the bottom to use a socket wrench to operate the high-strength bolt 320, greatly improving the efficiency of on-site assembly.

[0032] The method for the above-mentioned wedge-shaped self-locking detachable steel-concrete composite beam shear connection node includes the following steps: S1. Factory prefabrication stage: During the production of the precast concrete layer 200, the shear connector 310 is fixed inverted in the template according to the designed hole position, and the outer surface is coated with an isolation and release medium. After the concrete is poured and cured, the shear connector 310 is permanently embedded in the concrete, forming a naturally fitting reserved cavity. S2. On-site assembly stage: The precast concrete layer 200 with shear-resistant connector 310 at the bottom is lowered to the steel beam 100 using lifting equipment, so that the shear-resistant protrusion 312 falls precisely into the shear-resistant groove 112 to achieve preliminary mechanical positioning. S3. Bottom-mounted fastening stage: From below the steel beam 100, the construction personnel pass the high-strength bolt 320 through the flat washer 322 and the reserved hole 111 from bottom to top, and then screw the thread into the internal thread blind hole 313. A torque wrench is used to apply pre-tightening force to complete the dry assembly.

[0033] The overall working principle of this connection node is as follows: When the composite beam undergoes bending deformation under external loads, a huge horizontal shear force V is generated at the interface between the steel beam 100 and the precast concrete layer 200. Under the action of this shear force, the wedge-shaped outer peripheral surface of the shear connector 310 is pressed against the wall of the reserved receiving cavity inside the precast concrete layer 200. Utilizing the sloping geometry of the upper surface being larger than the lower surface, this contact surface generates a strong wedge-shaped self-locking effect, converting part of the horizontal thrust into a downward normal compressive force.

[0034] During this process, the shear protrusion 312 at the bottom of the shear connector 310 forms a strong mechanical engagement with the shear groove 112. The destructive horizontal shear force V is almost entirely borne by this engagement surface, thereby ensuring that the internal high-strength bolt 320 is in a zero-shear state and only bears axial tension, completely eliminating the engineering hazard of bolts being directly sheared off in traditional joints.

[0035] During the dismantling phase when the building reaches the end of its service life or when components need to be replaced, since the fastening components are completely below the steel beam 100, operators only need to use a wrench to unload the high-strength bolts 320 and the flat washers 322 in reverse to release the axial constraint between the steel beam 100 and the concrete. Subsequently, the precast concrete layer 200 is lifted directly upwards using lifting equipment. Thanks to the unobstructed truncated cone structure of the shear connector 310 and the isolation medium on its surface, the shear connector 310, along with the precast concrete layer 200, is safely lifted away together without any concrete demolition or gas cutting operations, achieving 100% green recycling and non-destructive dismantling of the steel and precast concrete components.

[0036] Therefore, the present invention adopts the above-mentioned wedge-shaped self-locking detachable steel-concrete composite beam shear connection node and method. During dismantling, only the high-strength bolts at the bottom need to be removed to achieve complete and non-destructive separation of the steel beam from the precast concrete layer. The entire process does not require the demolition of the main components, which greatly improves the green recycling rate and construction convenience of prefabricated buildings.

[0037] Finally, it should be noted that the above 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 with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A wedge-shaped self-locking detachable steel-concrete composite beam shear connection node, characterized in that: It includes a steel beam and a precast concrete layer. The precast concrete layer has several embedded molding cavities. Each embedded molding cavity is provided with a set of shear connection components, which are used to connect with the steel beam. Several sets of supporting components are provided at the upper flange of the steel beam. The supporting components are fitted and connected with the shear-resistant connecting components, and both the shear-resistant connecting components and the supporting components are connected by fastening components through and pressing them together. The shear-resistant connection assembly includes a shear-resistant connector embedded in the pre-embedded molding cavity. The shear-resistant connector is configured as an inverted frustum-shaped wedge structure, and the outer surface of the shear-resistant connector is coated with an isolation medium. The receiving component includes a plurality of reserved holes formed on the upper flange, and a shear groove is formed downward around the reserved holes at the top surface of the upper flange; The bottom surface of the shear connector protrudes from the bottom surface of the precast concrete layer, and the bottom surface of the shear connector is provided with a shear protrusion, which is fitted and connected to the shear groove. The shear connector has an internally threaded blind hole in the vertical direction at its internal center, and the internally threaded blind hole is connected to the fastening assembly. The fastening assembly includes a high-strength bolt and a flat washer. The flat washer is disposed on the bottom surface of the upper flange and located outside the reserved hole. The high-strength bolt passes through the flat washer, the reserved hole and the internal thread blind hole from bottom to top in sequence and is connected by threads.

2. The wedge-shaped self-locking detachable steel-concrete composite beam shear connection node according to claim 1, characterized in that: The vertical depth of the internally threaded blind hole is greater than the effective thread length of the high-strength bolt when it is screwed into the shear-resistant connector.

3. The wedge-shaped self-locking detachable steel-concrete composite beam shear connection node according to claim 2, characterized in that: An air-proof cavity is provided between the top of the internally threaded blind hole and the top of the high-strength bolt.

4. The wedge-shaped self-locking detachable steel-concrete composite beam shear connection node according to claim 3, characterized in that: The diameter of the reserved hole is larger than the diameter of the portion through which the high-strength bolt passes, in order to reserve a gap for engineering installation.

5. The wedge-shaped self-locking detachable steel-concrete composite beam shear connection node according to claim 4, characterized in that: The reserved holes and the shear-resistant connectors are arranged in a double-row symmetrical structure that avoids the web of the steel beam.

6. The method for applying the wedge-shaped self-locking detachable steel-concrete composite beam shear connection node as described in claim 5, characterized in that, Includes the following steps: S1. Factory Prefabrication Stage: During the production of the precast concrete layer, the shear connector is fixed upside down in the template according to the designed hole position, and the outer surface is coated with an isolation and release medium. After the concrete is poured and cured, the shear connector is permanently embedded in the concrete, forming a naturally fitting reserved cavity. S2. On-site assembly stage: The precast concrete layer with shear-resistant connectors at the bottom is lowered onto the steel beam using lifting equipment, so that the shear-resistant protrusions fall precisely into the shear-resistant grooves to achieve preliminary mechanical positioning. S3, Bottom-mounted fastening stage: From below the steel beam, the construction personnel pass the high-strength bolts through the flat washers and reserved holes from bottom to top, then screw them into the internal thread blind holes, and apply pre-tightening force with a torque wrench to complete the dry assembly.

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