A steel-concrete interface shear bearing test push-out specimen and its preparation method and application

Abstract

A steel-concrete interface shear bearing test push-out specimen, the push-out specimen includes a steel plate, a shear connector, a rigid connector and a concrete plate. The shear connector includes two half-cut shear members, that is, the two half-cut shear members are connected by a rigid connector to equivalently simulate a complete shear connector. The two half-cut shear members are symmetrically fixed on the two side edges of the steel plate, and the cross-sections of the two half-cut shear members are flush with the side of the steel plate. The steel-concrete interface shear bearing test push-out specimen provided by the present invention can perform an interface destruction test under visual conditions, and can observe and measure the formation of load deformation between the local concrete wedge and the root of the bolt, the destruction process and the stress-deformation response in situ, which has important scientific significance for accurately evaluating the force transmission performance and fatigue life of the steel-concrete interface and improving the design theory of steel-concrete structures.

Description

Technical Field

[0001] The invention relates to a steel-concrete interface shear bearing test device, in particular to a steel-concrete interface shear bearing test push-out specimen and a preparation method and application thereof, belonging to the technical field of civil engineering structure experimental testing. Background Art

[0002] Steel-concrete composite structure refers to a component in which steel plates and concrete plates are connected into an integral whole through shear connectors. Due to its advantages such as high bearing capacity, high rigidity and good stability, it is widely used in civil engineering related fields such as bridge structures and building structures, and has achieved good economic benefits.

[0003] The effective connector of the steel-concrete interface is the key prerequisite to ensure the normal service of the composite structure. The interface is connected by a shear connector. Under the action of load, the interface will slip to a certain extent. The steel plate, shear connector and concrete interact and deform. The shear force of the upper concrete is transmitted to the lower steel beam through the shear connector and the interface friction. At present, domestic and foreign scholars have carried out a lot of research on the performance of the steel-concrete interface connected by studs through traditional ordinary push-out specimens, and proposed the concept of local concrete wedges. It is believed that the shear force of the steel-concrete interface is mainly transmitted to the lower steel plate through the studs and the local concrete wedges at their roots. This wedge effect is closely related to the failure process of the steel-concrete interface and cannot be ignored. The observation of the failure process of the steel-concrete interface is particularly important. Using the traditional steel-concrete composite structure push-out specimen (such as CN201210416210), due to the concealed formation position of the local concrete wedge and the very limited load-deformation response range between the roots of the studs, it is difficult to visualize its formation, failure process and stress-deformation response. Therefore, a visual specimen that can continuously observe it during the interface failure process is needed. Summary of the invention

[0004] In view of the problems existing in the prior art, a push-out specimen for shear bearing test on a steel-concrete interface and a preparation method and application thereof are provided. The push-out specimen for shear bearing test on a steel-concrete interface proposed in the present invention divides a shear connector into two half-section shear members and symmetrically arranges them in pairs on both side edges of a steel plate. After the concrete plate is cast, the cross-section of the half-section shear member is exposed to the outside of the concrete plate and is flush with the side of the concrete plate. The top ends of the two symmetrically arranged half-section shear members are connected to form a complete shear connector through a rigid connector. The push-out specimen for shear bearing test on a steel-concrete interface provided by the present invention can intuitively observe the destruction process when conducting a steel-concrete interface destruction test.

[0005] According to a first embodiment of the present invention, a push-out specimen for a steel-concrete interface shear bearing test is provided.

[0006] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate, a shear connector, a rigid connector and a concrete plate. The shear connector comprises two half-section shear members, that is, the two half-section shear members are connected by a rigid connector to simulate a complete shear connector. The two half-section shear members are symmetrically fixed on the two side edges of the steel plate, and the cross-sections of the two half-section shear members are flush with the side surfaces of the steel plate. The tops of the two symmetrically arranged half-section shear members are connected by a rigid connector. The concrete plate is cast between the steel plate, the two symmetrically arranged half-section shear members and the rigid connector, wherein: the bottom surface of the concrete plate is tightly fitted with the upper surface of the steel plate, the two side surfaces of the concrete plate are flush with the cross-sections of the two half-section shear members, and the horizontal height of the upper surface of the concrete plate is not lower than the horizontal height of the top of the half-section shear member.

[0007] Preferably, the rigid connector is a strip steel connector, both ends of which are fixedly connected to the inner side of the top end of the half-split shear member. After the concrete slab is cast, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab or the strip steel connector is cast as a whole inside the concrete slab. Preferably, the rigidity of the strip steel connector is greater than the rigidity of the half-split shear member.

[0008] Preferably, the rigid connector is a ∩-shaped steel connector with two ends bent (i.e., both ends of the bar steel are bent 90° in the same direction), and the two ends of the bent portion of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-section shear member. After the concrete slab is cast, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab. Preferably, the rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-section shear member.

[0009] Preferably, the push-out specimen comprises 1 to 20 pairs of symmetrically arranged half-split shear members, preferably 2 to 12 pairs of symmetrically arranged half-split shear members, and more preferably 4 to 8 pairs of symmetrically arranged half-split shear members. The top ends of any pair of symmetrically arranged half-split shear members are connected by a rigid connector.

[0010] Preferably, the concrete slab is further provided with internal reinforcement ribs. Preferably, the internal reinforcement ribs are steel mesh.

[0011] Preferably, the steel plate is an I-beam, and the I-beam includes a web and two wing plates, the two wing plates are respectively arranged at the two ends of the web, the two wing plates are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web. Multiple pairs of symmetrically arranged half-section shear members and concrete slabs are arranged on the two side edges of the two wing plates. Preferably, the same number of half-section shear members are arranged on the two wing plates. It should be noted that when the steel plate in the push-out specimen of the steel-concrete interface shear bearing test of the present invention is an I-beam, the push-out specimen takes the central axis of the web of the I-beam as the center of symmetry, and the wing plates located on both sides of the central axis and the concrete slabs and half-section shear members arranged on the wing plates are designed to be symmetrical to each other.

[0012] Preferably, the half-section shear member is one of an axially half-sectioned bar steel, an axially half-sectioned PBL, and an axially half-sectioned bolt.

[0013] According to a second embodiment of the present invention, a method for preparing a push-out specimen for a steel-concrete interface shear bearing test is provided.

[0014] A method for preparing a push-out specimen for a steel-concrete interface shear bearing test, the method comprising the following steps:

[0015] 1) The shear connector is cut in half along its axial direction to obtain two half-cut shear members, and then the two half-cut shear members are symmetrically fixed on the two side edges of the steel plate or on the two side edges of the I-beam flange, wherein the cross-section of the half-cut shear member is flush with the two side sides of the steel plate or the two side sides of the flange.

[0016] Alternatively, two shear connectors are symmetrically fixed on the two side edges of the steel plate or on the two side edges of the I-beam wing plate, and then the two shear connectors are milled along their central axes to form two symmetrically arranged half-section shear members, wherein the cross-section of the half-section shear member is flush with the two side surfaces of the steel plate or the two side surfaces of the wing plate.

[0017] 2) Use a strip-shaped rigid connector or a ∩-shaped rigid connector to connect the top ends of two symmetrically arranged half-section shear members into a whole.

[0018] 3) A steel mesh layer may or may not be provided between the rigid connector and the two symmetrically arranged half-section shear members.

[0019] 4) First, make the concrete casting formwork. Then, according to the casting formwork, cast the two symmetrically arranged half-cut shear members, rigid connectors and steel mesh layer into the concrete to form a concrete slab. After curing, remove the formwork to obtain the steel-concrete interface shear bearing test push-out specimen.

[0020] According to a third embodiment of the present invention, there is provided an application of a push-out specimen for a steel-concrete interface shear bearing test.

[0021] The invention discloses an application of a push-out specimen for a shear bearing test on a steel-concrete interface. The push-out specimen for the shear bearing test on a steel-concrete interface is applied to a test for observing the interface destruction of a steel-concrete composite structure.

[0022] Preferably, the destructive test is: measuring the load value and interface slip amount of the steel-concrete interface shear bearing test push-out specimen by means of a pressure sensor and a displacement sensor, and visually testing the stress-strain response, damage accumulation and destruction process of the local area of ​​the half-sectioned shear member, steel plate and concrete slab using a non-contact video extensometer and a high-power metallographic microscope.

[0023] In the prior art, the shear force at the steel-concrete interface is mainly transmitted to the lower steel plate through the shear connector and the local concrete wedge at its root. In actual tests, such as CN201210416210, shear connectors are often buried inside the concrete slab. When performing interface shear bearing tests, the shear connectors cannot be observed intuitively, and the failure process and stress-deformation response process of the shear connectors cannot be directly observed. As a result, it is impossible to accurately evaluate and measure the force transmission performance and fatigue life of the steel-concrete interface, and further, it is impossible to analyze the bearing capacity of the shear force on the steel-concrete interface. In the actual test process, since it is impossible to directly observe the inside of the push-out specimen, the shear connector can only be completely destroyed when the applied external force exceeds the maximum tolerable force of the push-out specimen in the steel-concrete interface shear bearing test, that is, only the shear force when the specimen is completely destroyed can be recorded. Since it is impossible to directly observe the specific failure process of the concrete or shear connector inside the push-out specimen (such as the stress condition when the shear connector begins to crack), it is impossible to accurately determine the load value when the push-out specimen begins to crack, resulting in inaccurate calculated safety limit load in actual applications. That is to say, in actual engineering, there are still uncertainties in determining the safety load value based on the shear load value and empirical coefficient when the shear connector is completely destroyed, which can easily lead to safety accidents. For example, suppose a shear connector will be damaged to a certain extent (such as cracks begin to appear) at 9000N, but because the shear connector is completely buried in concrete, it is impossible to directly observe the destruction process of the shear connector, nor is it known whether the shear connector is damaged. If the shear connector is completely destroyed under the external force of 10000N; the technical solution in the prior art can only test that the shear force when the shear connector is completely destroyed (completely broken) is 10000N, and the reference empirical coefficient is 0.95, then the limited safe load value in the actual project is set to 9500N; therefore, in actual engineering, when the load value is between 9000-95000N, although it is in the safe load value range, the load values ​​in this range are all greater than 9000N, so safety accidents are very likely to occur. At the same time, the existing specimens cannot observe the cracks caused by fatigue in the concrete slab and shear connectors during actual practical use, let alone the initiation of cracks and the damage of concrete. In summary, how to realize real-time visual testing of the steel-concrete interface, and record the local stress-strain response, damage accumulation and destruction process of the push-out specimen under a certain load, and explore the safe load value of the push-out specimen in the shear bearing test of the steel-concrete interface is of great significance.

[0024] In the present invention, the shear connector is divided into two half-section shear connectors, and the two half-section shear connectors are symmetrically fixed on the two side edges of the steel plate, and the cross-sections of the two half-section shear connectors are flush with the sides of the steel plate, so that the shear connector is exposed outside the concrete slab. Since the maximum load value of the half-section shear connector is different from that of the complete shear connector, the present invention replaces the two half-section shear connectors with a complete shear connector through a rigid connector, so that the two half-section shear connectors are subjected to force together, reducing the impact of the milling shear connector, and at the same time, a visual test of the interface destruction test of the steel-concrete composite structure is performed.

[0025] In the present invention, there are two ways of connecting the rigid connector and the shear connector. One is that the rigid connector is a strip steel connector, and the two ends of the steel connector are respectively fixed on the inner side of the top of the half-section shear connector, and the upper surface of the steel connector is flush with the upper surface of the concrete slab, or the steel connector is cast in its entirety inside the concrete slab. Another way of connecting is that the steel connector is a ∩-shaped steel connector, and the bending parts at both ends of the ∩-shaped steel connector are respectively fixed on the outer side of the top of the half-section shear connector. After the concrete slab is cast, the ∩-shaped steel connector fits the upper surface of the concrete slab. The ∩-shaped steel connector described here is a strip steel with a straight middle section and two ends bent at 90°, and the bending parts are respectively fixed on the outer side of the top of the half-section shear connector. The rigidity of the rigid connectors selected for the two connection methods is greater than the rigidity of the shear connector, so as to ensure the common force between the two connected half-section shear members.

[0026] In the present invention, the inner side is the side cast inside the concrete slab or the side close to the inside of the steel-concrete interface shear bearing test push-out specimen, and the outer side is the side exposed outside the concrete slab or the side close to the outside of the steel-concrete interface shear bearing test push-out specimen.

[0027] In the present invention, the steel plate is an I-beam, and the two wing plates of the I-beam are provided with symmetrically arranged half-cut shear members, the number of pairs of the half-cut shear members can be freely adjusted, and preferably, the number of pairs of the half-cut shear members on the two wing plates is equal.

[0028] In the present invention, built-in reinforcing ribs are arranged inside the concrete slab to reinforce the concrete slab.

[0029] In the present invention, pressure sensors and displacement sensors are used to measure the load value and interface slip amount of the push-out specimen of the steel-concrete interface shear bearing test, and a non-contact video extensometer and a high-power metallographic microscope are used to perform a visual test on the stress-strain response, damage accumulation and destruction process of the local area of ​​the half-sectioned shear member, steel plate and concrete slab, so that the ultimate load value of the push-out specimen of the steel-concrete interface shear bearing test in a safe state can be measured.

[0030] In the present invention, the steel-concrete interface shear bearing test push-out specimen provided by the present invention can observe and measure the formation, destruction process and stress-deformation response of the load deformation between the local concrete wedge and the root of the stud during the loading process in situ in the static load test, accurately reveal the friction effect mechanism of the steel-concrete interface and the law of interface shear force distribution, and can also timely and accurately observe and measure the initiation and expansion of fatigue cracks of studs and steel plates and the destruction of concrete under different fatigue loading times in the fatigue test, thereby more accurately revealing the destruction process of the steel-concrete composite specimen, and providing a basis for establishing a more accurate bearing capacity and fatigue life prediction method. It has important scientific significance for accurately evaluating the force transmission performance and fatigue life of the steel-concrete interface and improving the design theory of steel-concrete structures.

[0031] In the present invention, the PBL is a perforated steel plate shear connector.

[0032] In the present invention, the length of the steel plate is 50 mm to 1200 mm, preferably 100 mm to 1000 mm, more preferably 200 mm to 800 mm, and more preferably 400 mm to 600 mm. The width of the steel plate is 10 mm to 500 mm, preferably 30 mm to 400 mm, more preferably 50 mm to 200 mm, and more preferably 100 mm to 150 mm.

[0033] In the present invention, the height of the shear connector is 5 mm to 200 mm, preferably 10 mm to 150 mm, more preferably 20 mm to 80 mm, and even more preferably 40 mm to 60 mm.

[0034] In the present invention, the spacing between the two half-split shear members is 10 mm to 500 mm, preferably 20 mm to 300 mm, more preferably 50 mm to 200 mm, and more preferably 100 mm to 150 mm.

[0035] In the present invention, the thickness of the concrete slab is 5 mm to 200 mm thicker than the height of the shear connector, preferably 8 mm to 100 mm thicker, more preferably 10 mm to 50 mm thicker, and more preferably 20 mm to 40 mm thicker.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The steel-concrete interface shear bearing test push-out specimen provided by the present invention can perform interface destruction tests under visual conditions, and can observe and measure in situ the formation of load deformation between the local concrete wedge and the root of the stud, the destruction process, and the stress-deformation response, thereby having important scientific significance for accurately evaluating the force transmission performance and fatigue life of the steel-concrete interface and improving the design theory of steel-concrete structures.

[0038] 2. The method for preparing the steel-concrete interface shear bearing test specimen provided by the present invention is simple, the raw materials are easily available, and it has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic structural diagram of a steel-concrete interface shear bearing test push-out specimen provided by the present invention.

[0040] Figure 2 A schematic diagram of the internal structure of a steel-concrete interface shear bearing test push-out specimen provided by the present invention.

[0041] Figure 3 Another structural schematic diagram of a steel-concrete interface shear bearing test push-out specimen provided by the present invention.

[0042] Figure 4 A test piece is introduced for the shear bearing test of the steel-concrete interface in the prior art.

[0043] Figure 5 The invention provides a steel-concrete interface shear bearing test push-out specimen.

[0044] Figure 6 The invention provides a steel-concrete interface shear bearing test, in which a specimen is pushed out to carry out a static loading test and the failure characteristics of the studs, steel plates and concrete are measured.

[0045] Figure 7 A steel-concrete interface shear bearing test provided by the present invention is carried out by pushing out a specimen to carry out a fatigue loading test, and the damage characteristics of the bolts, steel plates and concrete measured change with the fatigue times (800,000 times, 1 million times, 1.2 million times, 1.5 million times, and 1.8 million times, respectively).

[0046] Figure 8 The schematic diagram of the loading arrangement for the specimen interface destruction test is presented for the steel-concrete interface shear bearing test.

[0047] Figure numerals: 1: steel plate; 101: web; 102: flange; 2: shear connector; 201: half-split shear member; 3: rigid connector; 4: concrete slab; 5: built-in reinforcement. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0049] According to a first embodiment of the present invention, a push-out specimen for a steel-concrete interface shear bearing test is provided.

[0050] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0051] Preferably, the rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-cut shear member 201. After the concrete slab 4 is cast, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab 4 or the strip steel connector is cast as a whole inside the concrete slab 4. Preferably, the rigidity of the strip steel connector is greater than the rigidity of the half-cut shear member 201.

[0052] Preferably, the rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. Preferably, the rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0053] Preferably, the push-out specimen includes 1 to 20 pairs of symmetrically arranged half-split shear members 201, preferably 2 to 12 pairs of symmetrically arranged half-split shear members 201, and more preferably 4 to 8 pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3.

[0054] Preferably, the concrete slab 4 is further provided with internal reinforcement ribs 5. Preferably, the internal reinforcement ribs 5 are steel meshes.

[0055] Preferably, the steel plate 1 is an I-beam, which includes a web 101 and two flanges 102, the two flanges 102 are respectively arranged at the two ends of the web 101, the two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on both side edges of the two flanges 102. Preferably, the same number of pairs of half-cut shear members 201 are arranged on the two flanges 102.

[0056] Preferably, the half-section shear member 201 is one of an axially half-sectioned bar steel, an axially half-sectioned PBL, and an axially half-sectioned stud.

[0057] In the present invention, the PBL is a perforated steel plate shear connector.

[0058] In the present invention, the length of the steel plate is 50 mm to 1200 mm, preferably 100 mm to 1000 mm, more preferably 200 mm to 800 mm, and more preferably 400 mm to 600 mm. The width of the steel plate is 10 mm to 500 mm, preferably 30 mm to 400 mm, more preferably 50 mm to 200 mm, and more preferably 100 mm to 150 mm.

[0059] In the present invention, the height of the shear connector is 5 mm to 200 mm, preferably 10 mm to 150 mm, more preferably 20 mm to 80 mm, and even more preferably 40 mm to 60 mm.

[0060] In the present invention, the spacing between the two half-split shear members is 10 mm to 500 mm, preferably 20 mm to 300 mm, more preferably 50 mm to 200 mm, and more preferably 100 mm to 150 mm.

[0061] In the present invention, the thickness of the concrete slab is 5 mm to 200 mm thicker than the height of the shear connector, preferably 8 mm to 100 mm thicker, more preferably 10 mm to 50 mm thicker, and more preferably 20 mm to 40 mm thicker.

[0062] According to a second embodiment of the present invention, a method for preparing a push-out specimen for a steel-concrete interface shear bearing test is provided.

[0063] A method for preparing a push-out specimen for a steel-concrete interface shear bearing test, the method comprising the following steps:

[0064] 1) The shear connector 2 is cut in half along its axial direction to obtain two half-cut shear members 201, and then the two half-cut shear members 201 are symmetrically fixed on the two side edges of the steel plate 1 or on the two side edges of the I-beam flange 102, wherein the cross-section of the half-cut shear member 201 is flush with the two side sides of the steel plate 1 or the two side sides of the flange 102.

[0065] Alternatively, the two shear connectors 2 are symmetrically fixed on the two side edges of the steel plate 1 or on the two side edges of the I-beam wing plate 102, and then the two shear connectors 2 are milled along their central axis to form two symmetrically arranged half-section shear members 201, wherein the cross-section of the half-section shear member 201 is flush with the two side sides of the steel plate 1 or the two side sides of the wing plate 102.

[0066] 2) A strip-shaped rigid connector 3 or a ∩-shaped rigid connector 3 is used to connect the top ends of two symmetrically arranged half-cut shear members 201 into a whole.

[0067] 3) A steel mesh layer is provided or not provided between the rigid connector 3 and the two symmetrically arranged half-cut shear members 201 .

[0068] 4) First, make concrete casting formwork. Then, according to the casting formwork, two symmetrically arranged half-cut shear members 201, rigid connectors 3 and steel mesh layers are cast into concrete to form a concrete slab 4. After curing, the formwork is removed to obtain a steel-concrete interface shear bearing test push-out specimen.

[0069] According to a third embodiment of the present invention, there is provided an application of a push-out specimen for a steel-concrete interface shear bearing test.

[0070] The invention discloses an application of a push-out specimen for a shear bearing test on a steel-concrete interface. The push-out specimen for the shear bearing test on a steel-concrete interface is applied to a test for observing the interface destruction of a steel-concrete composite structure.

[0071] Preferably, the destructive test is: the load value and interface slip amount of the steel-concrete interface shear bearing test push-out specimen are measured by a pressure sensor and a displacement sensor, and a non-contact video extensometer and a high-power metallographic microscope are used to perform a visual test on the stress-strain response, damage accumulation and destruction process of the local area of ​​the half-cut shear member 201, the steel plate 1 and the concrete plate 4.

[0072] Example 1

[0073] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0074] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is poured, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab 4. The rigidity of the strip steel connector is greater than the rigidity of the half-split shear member 201.

[0075] The steel plate 1 is a rectangular steel plate; the push-out specimen includes four pairs of symmetrically arranged half-cut shear members 201. The top ends of any pair of symmetrically arranged half-cut shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0076] The half-split shear member 201 is an axially half-split bolt.

[0077] Example 2

[0078] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0079] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is cast, the strip steel connector is cast as a whole inside the concrete slab 4. The rigidity of the strip steel connector is greater than that of the half-split shear member 201.

[0080] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0081] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0082] The half-split shear member 201 is an axially half-split bolt.

[0083] Example 3

[0084] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0085] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is cast, the strip steel connector is cast as a whole inside the concrete slab 4. The rigidity of the strip steel connector is greater than that of the half-split shear member 201.

[0086] The push-out specimen includes 6 pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0087] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Three pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0088] The half-split shear member 201 is an axially half-split bolt.

[0089] Example 4

[0090] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0091] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is cast, the strip steel connector is cast as a whole inside the concrete slab 4. The rigidity of the strip steel connector is greater than that of the half-split shear member 201.

[0092] The push-out specimen includes 10 pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0093] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Five pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0094] The half-split shear member 201 is an axially half-split bolt.

[0095] Example 5

[0096] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0097] The rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. The rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0098] The steel plate 1 is a rectangular steel plate; the push-out specimen includes four pairs of symmetrically arranged half-cut shear members 201. The top ends of any pair of symmetrically arranged half-cut shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0099] The half-split shear member 201 is an axially half-split bolt.

[0100] Example 6

[0101] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0102] The rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. The rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0103] The push-out specimen includes 6 pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0104] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Three pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0105] The half-split shear member 201 is an axially half-split bolt.

[0106] Example 7

[0107] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0108] The rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. The rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0109] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0110] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0111] The half-split shear member 201 is an axially half-split bolt.

[0112] Example 8

[0113] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0114] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is cast, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab 4 or the strip steel connector is cast as a whole inside the concrete slab 4. The rigidity of the strip steel connector is greater than that of the half-split shear member 201.

[0115] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0116] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0117] The half-split shear member 201 is an axially half-split PBL.

[0118] Example 9

[0119] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0120] The rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. The rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0121] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0122] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0123] The half-split shear member 201 is an axially half-split PBL.

[0124] Example 10

[0125] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0126] The rigid connector 3 is a strip steel connector, and both ends of the strip steel connector are respectively fixedly connected to the inner side of the top end of the half-split shear member 201. After the concrete slab 4 is cast, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab 4 or the strip steel connector is cast as a whole inside the concrete slab 4. The rigidity of the strip steel connector is greater than that of the half-split shear member 201.

[0127] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0128] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0129] The half-section shear member 201 is a strip steel that is axially half-sectioned.

[0130] Embodiment 11

[0131] A push-out specimen for shear bearing test of steel-concrete interface, the push-out specimen comprises a steel plate 1, a shear connector 2, a rigid connector 3 and a concrete plate 4. The shear connector 2 comprises two half-section shear members 201, that is, the two half-section shear members 201 are connected by a rigid connector 3 to equivalently simulate a complete shear connector 2. The two half-section shear members 201 are symmetrically fixed on the two side edges of the steel plate 1, and the cross-sections of the two half-section shear members 201 are flush with the side surfaces of the steel plate 1. The top ends of the two symmetrically arranged half-section shear members 201 are connected by a rigid connector 3. The concrete slab 4 is cast between the steel plate 1, two symmetrically arranged half-section shear members 201 and the rigid connector 3, wherein: the bottom surface of the concrete slab 4 is tightly fitted with the upper surface of the steel plate 1, the two side surfaces of the concrete slab 4 are respectively flush with the cross-sections of the two half-section shear members 201, and the horizontal height of the upper surface of the concrete slab 4 is not lower than the horizontal height of the top of the half-section shear member 201.

[0132] The rigid connector 3 is a ∩-shaped steel connector with two ends bent, and the two ends of the ∩-shaped steel connector are respectively fixedly connected to the top outer side of the half-cut shear member 201. After the concrete slab 4 is poured, the inner surface of the ∩-shaped steel connector is tightly fitted with the upper surface of the concrete slab 3. The rigidity of the ∩-shaped steel connector is greater than the rigidity of the half-cut shear member 201.

[0133] The push-out specimen includes four pairs of symmetrically arranged half-split shear members 201. The top ends of any pair of symmetrically arranged half-split shear members 201 are connected by a rigid connector 3. A steel mesh is also arranged inside the concrete slab 4.

[0134] The steel plate 1 is an I-beam, which includes a web 101 and two flanges 102. The two flanges 102 are respectively arranged at the two ends of the web 101. The two flanges 102 are parallel to each other and their plate surfaces are perpendicular to the plate surface of the web 101. Multiple pairs of symmetrically arranged half-cut shear members 201 and concrete slabs 4 are arranged on the edges of both sides of the two flanges 102. Two pairs of half-cut shear members 201 are independently arranged on the two flanges 102.

[0135] The half-section shear member 201 is a strip steel that is axially half-sectioned.

[0136] Comparative Example 1

[0137] A steel-concrete interface shear bearing test push-out specimen, the push-out specimen comprises a steel plate, a shear connector and a concrete plate. The shear connector is arranged at the center of the steel plate. The concrete plate is cast on the steel plate and covers the shear connector, the bottom surface of the concrete plate and the surface of the steel plate, the level of the upper surface of the concrete plate is the level of the top of the shear connector.

[0138] The steel plate 1 is a rectangular steel plate;

[0139] The shear connector is a complete stud.

[0140] A steel mesh is also arranged inside the concrete slab.

[0141] Comparative Example 2

[0142] A steel-concrete interface shear bearing test push-out specimen, the push-out specimen comprises a steel plate, a shear connector and a concrete plate. The shear connector is arranged at the center of the steel plate. The concrete plate is cast on the steel plate and covers the shear connector, the bottom surface of the concrete plate and the surface of the steel plate, the level of the upper surface of the concrete plate is the level of the top of the shear connector.

[0143] The steel plate 1 is an I-beam;

[0144] The shear connector is a complete stud.

[0145] A steel mesh is also arranged inside the concrete slab.

[0146] The processes used in Examples 1 to 11 and Comparative Examples 1 to 2 are shown in Table 1.

[0147] Table 1:

[0148]

[0149]

[0150] The push-out specimens described in Examples 1 to 11 and Comparative Examples 1 to 2 were applied to the interface destruction test of steel-concrete composite structures.

[0151] Figure 4 A test specimen was produced for the steel-concrete interface shear bearing test of Comparative Example 2. Figure 5 A test specimen is introduced for a steel-concrete interface shear bearing test of Example 2.

[0152] The experimental process is as follows:

[0153] The electro-hydraulic servo system is used for loading, and the loading arrangement is as follows Figure 8As shown. The pushed-out specimen is placed on a pedestal, and a small amount of quartz sand is laid between the lower end of the specimen and the pedestal to ensure that the specimen is placed vertically and stably; a loading plate, a ball joint, a pressure sensor and a booster are arranged in sequence between the upper end of the specimen and the reaction frame. During loading, the booster moves downward to transfer the load to the specimen, and the load value is read through the pressure sensor; extensometers are arranged at the middle position on both sides of the specimen to read the slip amount of the steel-concrete interface, and a camera and a video extensometer are arranged on one side of the specimen to photograph and measure the interface damage characteristics during loading. Before loading, the specimen is pre-stressed with a pre-stressing load of 20kN. The load value and slip amount are automatically collected using a strain tester. The static loading test uses a monotonically continuous incremental load increase until the specimen is destroyed, and is controlled according to the displacement. The loading speed is 0.5mm / minute (the test results are shown in Figure 6 The fatigue load is applied by the actuator from the top of the specimen. The fatigue loading adopts the force-controlled sinusoidal loading method with a load frequency of 5 Hz (the test results are shown in Figure 7 shown).

[0154] because Figure 4 In the steel-concrete interface shear bearing test, the shear connector of the push-out specimen is located inside the concrete, and it is impossible to observe whether the specimen is damaged under different external forces. In other words, before the specimen is completely destroyed, it is impossible to observe whether the shear connector, steel plate and concrete of the specimen are damaged, and it is also impossible to observe the development characteristics of deformation and cracks of the shear connector, steel plate and concrete during fatigue. The specimen can only obtain the shear bearing capacity and fracture characteristics of complete destruction.

[0155] The steel-concrete interface shear bearing test specimen provided in Example 2 of the present invention is pushed out (such as Figure 5 Experiment as shown):

[0156] Figure 6 The failure characteristics of the studs, steel plates and concrete measured by the static loading test of the steel-concrete interface shear bearing test specimen provided in Example 2 of the present invention can be visualized to observe the process in which the shear connector is gradually emptied and the concrete is gradually destroyed under the action of external force. Among them: a, b, c, d are partial enlarged images of the visualized observation of the specimen.

[0157] Figure 7 In a steel-concrete interface shear bearing test provided in Example 2 of the present invention, a specimen is pushed out to carry out a fatigue loading test, and the damage characteristics of the studs, steel plates and concrete measured change with the fatigue times are measured.

[0158] The steel-concrete interface shear bearing test push-out specimen provided by the present invention can observe and measure in situ the formation of load deformation between the local concrete wedge and the root of the stud during loading, the failure process, and the stress-deformation response in a static load test. At the same time, the steel-concrete interface shear bearing test push-out specimen provided by the present invention can timely and accurately observe and measure the initiation and expansion of fatigue cracks in studs and steel plates and the failure of concrete under different fatigue loading times in a fatigue test, thereby more accurately revealing the failure process of the steel-concrete composite specimen, and providing a basis for establishing a more accurate and scientific bearing capacity and fatigue life prediction method. Comparative Example 2 ( Figure 4 ) The deformation and failure process of concrete slabs, shear connectors and steel plates cannot be observed in static load tests and fatigue tests.

Claims

1. A steel-concrete interface shear bearing test push-out specimen, characterized in that: The push-out specimen comprises a steel plate (1), a shear connector (2), a rigid connector (3) and a concrete plate (4); the shear connector (2) comprises two half-section shear members (201), that is, the two half-section shear members (201) are connected by a rigid connector (3) to equivalently simulate a complete shear connector (2); the two half-section shear members (201) are symmetrically fixedly arranged on the two side edges of the steel plate (1), and the cross-sections of the two half-section shear members (201) are flush with the side surfaces of the steel plate (1); the two half-section shear members (201) are symmetrically arranged. The top ends of the two half-section shear members (201) are connected via a rigid connector (3); the concrete slab (4) is cast between the steel plate (1), the two symmetrically arranged half-section shear members (201), and the rigid connector (3), wherein: the bottom surface of the concrete slab (4) is tightly fitted to the top surface of the steel plate (1), the two side surfaces of the concrete slab (4) are respectively flush with the cross-sections of the two half-section shear members (201), and the horizontal height of the top surface of the concrete slab (4) is not lower than the horizontal height of the top ends of the half-section shear members (201).

2. The steel-concrete interface shear bearing test push-out specimen according to claim 1, characterized in that: The rigid connector (3) is a strip steel connector, both ends of which are fixedly connected to the inner side of the top end of the half-cut shear member (201); after the concrete slab (4) is cast, the upper surface of the strip steel connector is flush with the upper surface of the concrete slab (4) or the strip steel connector is cast as a whole inside the concrete slab (4).

3. The steel-concrete interface shear bearing test push-out specimen according to claim 2, characterized in that: The rigidity of the strip steel connection piece is greater than the rigidity of the half-section shear member (201).

4. The steel-concrete interface shear bearing test push-out specimen according to claim 1, characterized in that: The rigid connector (3) is a ∩-shaped steel connector with two ends bent, and the two bent portions at both ends of the ∩-shaped steel connector are respectively fixedly connected to the outer side of the top end of the half-cut shear member (201); after the concrete slab (4) is poured, the inner surface of the ∩-shaped steel connector is tightly fitted to the upper surface of the concrete slab (4).

5. The steel-concrete interface shear bearing test push-out specimen according to claim 4, characterized in that: The rigidity of the ∩-shaped steel connecting member is greater than the rigidity of the half-section shear member (201).

6. The steel-concrete interface shear bearing test push-out specimen according to any one of claims 1 to 5, characterized in that: The push-out test piece comprises 1 to 20 pairs of symmetrically arranged half-split shear members (201); the top ends of any pair of symmetrically arranged half-split shear members (201) are connected via a rigid connecting member (3).

7. The steel-concrete interface shear bearing test push-out specimen according to claim 6, characterized in that: The push-out specimen includes 2 to 12 pairs of symmetrically arranged half-split shear members (201).

8. The steel-concrete interface shear bearing test push-out specimen according to claim 7, characterized in that: The push-out specimen includes 4 to 8 pairs of symmetrically arranged half-split shear members (201).

9. The steel-concrete interface shear bearing test push-out specimen according to any one of claims 1-5, 7-8, characterized in that: Built-in reinforcing ribs (5) are also provided inside the concrete slab (4).

10. The steel-concrete interface shear bearing test push-out specimen according to claim 9, characterized in that: The built-in reinforcing ribs (5) are steel meshes.

11. The steel-concrete interface shear bearing test push-out specimen according to any one of claims 1-5, 7-8, and 10, characterized in that: The steel plate (1) is an I-beam, comprising a web (101) and two wing plates (102), the two wing plates (102) being arranged at two ends of the web (101), the two wing plates (102) being parallel to each other and their plate surfaces being perpendicular to the plate surface of the web (101); and a plurality of pairs of symmetrically arranged half-section shear members (201) and a concrete slab (4) are arranged on both side edges of the two wing plates (102).

12. The steel-concrete interface shear bearing test push-out specimen according to claim 11, characterized in that: The two wing plates (102) are provided with the same number of half-split shear members (201).

13. The steel-concrete interface shear bearing test push-out specimen according to any one of claims 1-5, 7-8, 10, and 12, characterized in that: The half-section shear member (201) is one of an axially half-sectioned bar steel, an axially half-sectioned PBL, and an axially half-sectioned bolt.

14. A method for preparing a push-out specimen for a steel-concrete interface shear bearing test according to any one of claims 1 to 13, characterized in that: The method comprises the following steps: 1) The shear connector (2) is cut in half along its axial direction to obtain two half-cut shear members (201), and then the two half-cut shear members (201) are symmetrically fixed on the two side edges of the steel plate (1) or on the two side edges of the I-beam flange (102), wherein the cross-section of the half-cut shear member (201) is flush with the two side sides of the steel plate (1) or the two side sides of the flange (102); Alternatively, the two shear connectors (2) are symmetrically fixed on the two side edges of the steel plate (1) or on the two side edges of the I-beam flange (102), and then the two shear connectors (2) are respectively milled along their central axis to form two symmetrically arranged half-section shear members (201), wherein the cross-section of the half-section shear member (201) is flush with the two side surfaces of the steel plate (1) or the two side surfaces of the flange (102); 2) using a strip-shaped rigid connector (3) or a ∩-shaped rigid connector (3) to connect the top ends of two symmetrically arranged half-cut shear members (201) into a whole; 3) a steel mesh layer is provided or not provided between the rigid connection member (3) and the two symmetrically arranged half-cut shear members (201); 4) First, a concrete casting formwork is prepared; then, two symmetrically arranged half-cut shear members (201), a steel mesh layer, and a rigid connection member (3) are cast into concrete according to the casting formwork to form a concrete slab (4); after curing, the formwork is removed to obtain a steel-concrete interface shear bearing test push-out specimen.

15. An application of a steel-concrete interface shear bearing test push-out specimen according to any one of claims 1 to 13 or an application of a steel-concrete interface shear bearing test push-out specimen prepared by the method according to claim 14, characterized in that: The steel-concrete interface shear bearing test push-out specimen is applied to observe the interface failure test of steel-concrete composite structure.

16. The use according to claim 15, characterized in that: The destructive test comprises: measuring the load value and interface slip amount of the steel-concrete interface shear bearing test push-out specimen by means of a pressure sensor and a displacement sensor, and visually testing the stress-strain response, damage accumulation and destructive process of the local area of ​​the half-cut shear member (201), the steel plate (1) and the concrete plate (4) by means of a non-contact video extensometer and a high-power metallographic microscope.

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