CN211114418U - A detachable steel-concrete composite beam with damage-free main material - Google Patents

Abstract

The utility model discloses a detachable steel-concrete composite beam with damage-free main materials, which mainly comprises an I-shaped steel beam, a prefabricated reinforced concrete slab, a shear bolt set, an insert block and a steel cover plate. Prefabricated openings at symmetrical positions on the left and right sides of the upper flange of the I-shaped steel beam; steel bars are arranged in the prefabricated reinforced concrete slab, and there are reserved holes for inserting blocks at the corresponding positions of the bolts. The shape of the insert block is the same as that of the reserved hole. After the insert block is put in, it is completely fitted with the wall of the reserved hole. The concrete slab and the steel beam are connected by bolts; the shear bolt set is composed of studs and nuts. and gaskets. The components of the utility model are connected by detachable bolts instead of bolt welding. By weakening the cross section of the screw rod, the failure mode of the composite beam can be improved, the damage of the two main materials of the steel beam and the concrete slab can be avoided, the construction quality can be guaranteed, the use efficiency can be improved, and the convenience The main material is recycled and reused.

Description

A detachable steel-concrete composite beam with damage-free main material

technical field

The utility model relates to a detachable steel-concrete composite beam, in particular to a detachable steel-concrete composite beam whose main material is free from damage, belonging to the field of construction engineering.

Background technique

The steel-concrete composite beam is a component that connects the steel beam and the concrete slab into a whole through the shear connector. The shear connector is one of the key stress components in the steel-concrete composite beam, which can make the composite structure fully utilize the steel The advantages of good tensile properties and high compressive strength of concrete. The shear connection of steel-concrete composite beam structure adopts welded stud connection, which has poor construction quality and high cost, and is difficult to disassemble. The fatigue problem at the root weld is also prominent.

At present, my country is in the stage of large-scale urbanization construction. The construction waste generated by the demolition of the project has become an important issue of environmental protection and sustainable development. Therefore, it is particularly important to make the structure dismantled throughout the life cycle, which has broad application prospects. In recent years, bolted shear connectors have replaced welded studs as shear connectors in some composite beam members. The bolt shear connection is composed of a nut, a screw, a thread, a nut and a washer. The screw passes through the preset holes on the flange of the steel beam, and is fastened to the flange of the steel beam by the upper and lower nuts. Spacers are provided. Compared with the welded stud shear connection, the use of nuts to connect the stud rod and the steel beam is convenient for construction and operation and the connection quality is stable. Compared with welding, the installation of bolted connection can save more manpower, material resources and construction time, and reduce welding-related costs. At the same time, the bolted connection and the precast concrete slab can make the composite beam have the characteristics of disassembly, which is convenient for later maintenance and recycling.

Chinese patent CN103590322A discloses "a shear connector, a composite beam containing the shear connector, and a construction method", the structural principle of which is to set a steel plate between the concrete slab and the steel beam, and use the bolt shear connector to connect the concrete Plates, steel plates and steel beams are connected. Although this structure can strengthen the pre-tension effect of bolt shear connectors, it will cause damage to steel beams and concrete slabs, which is not conducive to disassembly and recycling of main material components. Bolts and steel beam flanges There are holes in the holes, and the relative positions of the bolts and the steel beams are staggered, so the rigidity of the bolted shear connection is reduced, and the rigidity and ultimate shear bearing capacity cannot be accurately predicted, and the ductility is poor.

Chinese patent CN108193588A discloses "a prefabricated steel-concrete composite beam shear key", the structural principle of which is to add steel filling plates on the upper and lower sides of the upper flange of the steel beam, and use high-strength bolts and nuts to connect the upper and lower steel filling plates to the upper flange of the steel beam. Tighten the precast concrete slab with reserved holes for secondary pouring, then place the precast concrete slab on the upper side of the steel beam and place it in place, and use UHPC to pour the reserved holes so that the precast concrete slab and the steel beam are connected by bolt shear force Although the structure can improve the integrity of the composite beam, improve the shear resistance and pre-tension effect of the shear connector, but the precast concrete slab, the steel beam and the bolted shear connector are connected by the wet connection method. The overall need to wait until the secondary poured UHPC reaches the bearing strength before it can be used. The bolted shear connection will cause damage to the steel beam and the concrete slab, which is not conducive to the disassembly and recycling of the main material components, and has rigidity and ultimate shear bearing capacity. The disadvantage is that the force cannot be accurately predicted and the ductility is poor.

To sum up, when using bolt shear connectors as shear connectors of detachable assembled composite beams, there are often the following problems: (1) Bolts are usually made of high-strength steel, and their strength is greater than that of steel beams. In practical applications, it is easy to cause damage to steel beams and concrete slabs, which is not conducive to later disassembly and recycling of steel beams and concrete slabs. The material of the bolt itself is relatively brittle, with low ductility and low elongation, resulting in the bolt as a shear connection. (2) At present, precast concrete slabs with reserved holes are used to connect the steel beams and bolt shear connectors into a whole by the wet connection method, and the composite beam needs to wait until the reserved hole fillers reach the strength (3) When the bolt shear connection occurs in the screw shear failure mode, the shear surface of the screw is usually located at the interface between the bottom surface of the concrete slab and the top surface of the steel beam flange. , There are threads on the screw ring surface, and the deformation of this section of the screw is too large or the local pressure damage to the steel beam flange screw hole causes the deformation to be too large, which will increase the construction difficulty of the later disassembly work, which is not conducive to the recycling of components; (4) When the interface between the concrete slab and the steel beam is damaged, the stress on the bolts, the reserved hole pouring material and the steel beam around the failure position before the failure is complicated, and it is difficult to deduce the theoretical formula for the accurate calculation of the ultimate shear bearing capacity and shear stiffness. It is not conducive to the accurate bearing design of the structure in the early stage, resulting in waste of materials; (5) The traditional bolts are used as shear connectors, and the preset openings and bolts of the steel beam flanges often leave holes, and the steel beams and bolts will be relatively dislocated, reducing the Stiffness of bolted shear connections.

SUMMARY OF THE INVENTION

The purpose of the utility model is to overcome the shortcomings of the prior art, and to provide a dismountable steel-concrete composite beam with no damage to the main material, adjustable shear stiffness, and better ductility.

The technical scheme of the present utility model is as follows:

The utility model discloses a detachable steel-concrete composite beam whose main material is free from damage, which comprises an I-shaped steel beam arranged in a horizontal direction, and a prefabricated concrete slab is supported on the upper flange of the I-shaped steel beam. A plurality of reserved holes are spaced at the front and back of the precast concrete plate, and an insert block that matches the shape of the reserved hole is installed in each reserved hole, and the top surface of the insert block is lower than the reserved hole. On the top surface of the hole, the bottom surface of the insert block is higher than the bottom surface of the reserved hole, and two screw connection holes are spaced left and right on each insert block. There is a steel beam connection hole, the upper part of each said steel beam connection hole is a tapered hole and the lower part is a circular hole with the same diameter as the bottom end of the tapered hole, and the top of the tapered hole is a large diameter. A conical nut is installed in the upper conical hole of each steel beam connecting hole, the lower part of the conical nut is in conformity with the shape of the conical hole, and the top wall of the conical nut is exposed to the workpiece. The top wall setting of the upper flange of the zigzag steel beam;

A double-ended stud is inserted into each screw connection hole, and the double-ended stud includes an upper threaded rod section, a smooth rod section and a lower threaded rod section connected in sequence from top to bottom; the double-ended stud The lower threaded rod section of the I-shaped steel beam is arranged through the corresponding conical nut, the steel beam connecting hole, the lower gasket and the lower nut in turn. The lower gasket is fixed on the bottom wall of the lower flange of the I-shaped steel beam by tightening the lower nut; and by tightening the lower nut, the conical nut is tightly fitted and fixed on the conical shape of the I-shaped steel beam on the wall of the hole; the upper part of the stud is covered with an upper gasket and screwed with an upper nut, and the upper gasket is fixed on the top wall of the insert block by tightening the upper nut; The upper threaded rod section and the smooth rod section of the head stud are arranged in the screw connection hole of the insert block; in each reserved hole, a steel cover plate supported on the double-ended stud is installed, and the steel cover plate and the prefabricated The concrete slabs are fixed together, and the upper surface of the steel cover is flush with the upper surface of the precast concrete slab.

Compared with the prior art, the utility model has the following advantages and outstanding effects:

1. The steel beam and the precast concrete slab are connected by bolts, which overcomes the welding quality and welding technical problems of stud welding, is easy to assemble and disassemble, can improve the use efficiency, and is conducive to the recovery and reuse of main materials, which is in line with the concept of green development.

2. By weakening the cross-section of the screw, intentionally induce the failure position to shift to the upper weakening position, so that the screw undergoes plastic yield at the weakened part first, thereby protecting the main material from damage, which can effectively avoid shear damage or damage to the contact surface between the concrete slab and the steel beam flange. Unfavorable failure modes for localized compression failure of steel girder flanges. By adjusting the weakening degree of the screw section, the design shear bearing capacity and shear stiffness of the bolted shear connection can be quantitatively designed, and the ductility and deformation capacity of the bolted shear connection can be improved.

3. By changing the distance between the lower surface of the high-strength mortar insert and the upper surface of the upper flange of the steel beam, the shear stiffness and shear bearing capacity of the shear connector can be adjusted, which is convenient for design calculation and can meet different construction requirements.

4. Compared with the traditional bolt-shear connector steel beam, the preset openings are straight bolt holes and have holes with the bolts, resulting in a decrease in the rigidity of the bolt-shear connector. The utility model uses conical nuts, which are embedded in the steel In the tapered screw holes reserved in the beam, the relative position of the bolt shear connector and the steel beam does not stagger, and the rigidity loss of the bolt shear connector caused by the relative stagger of the bolt is avoided.

5. Compared with the traditional wet connection method of precast concrete slab with reserved holes, steel beams and bolt shear connectors through cast-in-place reserved holes, it has to wait until the cast-in-place reserved hole material has bearing strength before it can be put into use. The disadvantage of the utility model is that each component of the utility model is a finished product made by a factory. Using the dry connection method, the assembly can be completed and can be put into use. It is suitable for roads and building facilities in emergency situations such as rescue and disaster relief.

Description of drawings

Fig. 1 is the structural schematic diagram of shear bolt sets in the detachable steel-concrete composite beam of the utility model that is free from damage to the main material;

Fig. 2 is the structural schematic diagram of inserting blocks in the detachable steel-concrete composite beam of the utility model whose main material is free from damage;

3 is a structural diagram of a bolt shear connector in a detachable steel-concrete composite beam of the present invention that is free from damage to the main material;

Fig. 4 is a schematic diagram of the feature size in the structure shown in Fig. 3;

Fig. 5 is the structural schematic diagram of the detachable steel-concrete composite beam of the utility model that is free from damage to the main material;

6 is a schematic diagram of the structure of reserved holes in the detachable steel-concrete composite beam of the present invention whose main material is free from damage.

Detailed ways

The present utility model will be described in detail below with reference to the accompanying drawings and a specific installation method.

As shown in the accompanying drawings, a detachable steel-concrete composite beam with damage-free main material of the present invention includes an I-shaped steel beam 10 arranged along the horizontal direction, and the upper flange of the I-shaped steel beam 10 is The upper support is provided with a prefabricated concrete slab 8, on the prefabricated concrete slab 8, a plurality of reserved holes are spaced before and after, and a plug 6 matching the shape of the reserved hole is installed in each reserved hole, The top surface of the described insert block 6 is lower than the top surface of the reserved hole, the bottom surface of the described insert block 6 is higher than the bottom surface of the reserved hole, and there are two screw connection holes spaced left and right on each insert block 6. 6-4, 6-5, a steel beam connecting hole is opened on the I-shaped steel beam 10 corresponding to each screw connecting hole, and the upper part of each said steel beam connecting hole is a conical hole and the lower part is a conical hole. It is a circular hole with the same diameter as the bottom end of the conical hole, the top of the conical hole is the large diameter end, and a conical nut is installed in the conical hole on the upper part of each steel beam connecting hole 4- 2. The lower part of the conical nut 4-2 matches the shape of the conical hole, and the top wall of the conical nut 4-2 is exposed to the top wall of the upper flange 7 of the I-shaped steel beam 10.

A double-ended stud is inserted into each screw connection hole, and the lower part of the double-ended stud passes through the corresponding conical nut 4-2, the steel beam connecting hole, and the lower gasket on the I-shaped steel beam 10 in turn. 5-2 and the lower nut 4-3 are provided, and the double-ended stud includes an upper threaded rod section 1, a smooth rod section 2 and a lower threaded rod section 3 which are connected in sequence from top to bottom.

The conical nut 4-2 is threadedly connected with the double-ended stud, and the lower gasket 5-2 is fixed on the bottom wall of the lower flange of the I-shaped steel beam 10 by tightening the lower nut 4-3. And by tightening the lower nut 4-3, the conical nut 4-2 is tightly fitted and fixed on the wall of the smooth conical hole of the upper flange 7 of the I-shaped steel beam 10. The upper part of the stud is covered with an upper washer 5-1 and is threadedly connected with an upper nut 4-1. The upper washer 5-1 is fixed on the insert block 6 by tightening the upper nut 4-1. on the top wall. As shown in FIG. 5 , the upper threaded rod section 1 and the smooth rod section 2 of the double-ended stud are used to be arranged in the screw connection hole of the insert block 6 . A steel cover plate 11 supported on the double-ended stud is installed in each reserved hole, the steel cover plate 11 is fixed with the precast concrete plate, and the upper surface of the steel cover plate 11 is connected with the prefabricated concrete plate 8 The top surface is flush.

Preferably, the generatrix of the tapered hole is 60° from the horizontal plane, and 60° is used as a common angle to facilitate drilling of steel beam flanges. Further preferably, the diameter D of the lower circular hole of the steel beam connecting hole is (d+2) mm, and d is double The outer diameter of the lower threaded rod section 3 of the head stud.

Preferably, a section of lower threaded rod section 3 that is higher than the top wall of the conical nut 4-2 and located between the bottom surfaces of the insert blocks 6 is used as the necked rod section, and the cross-sectional area of the necked rod section is smaller than that of the stud For the cross-sectional area of the remaining parts, the necked-down rod section is a section that reduces the cross-sectional area of the threaded rod, which can induce the bolt failure position to shift to the minimum cross-sectional area. The preferred necked-down rod section height is 5mm. And tighten the lower nut 4-3 with a torque wrench to apply a pre-tension force to the lower threaded rod segment 3 located between the conical nut 4-2 and the lower nut 4-3.

As shown in FIG. 6 , the reserved hole 9 is preferably composed of a semicircular truncated body on both sides and a square prism in the middle, which can reduce the proportion of the reserved hole to the concrete slab, and does not affect the overall reinforcement of the reinforcement and the concrete slab. The lateral plane ABCD of the semicircular truncated body is an isosceles trapezoid and is exactly the same as and coincides with the lateral surface of the quadrangular prism. The semicircular radius of the bottom surface of the reserved hole 9 is r ₂ =25mm. In order to reduce the sliding and stress concentration of the plug, the angle α ₂ =80° between the generatrix of the semicircular frustum of the reserved hole and the top wall of the upper flange of the steel beam.

Preferably, the insert block 6 adopts high-strength mortar with a compressive strength of not less than 100 MPa; the distance _h1 between the bottom surface of the insert block 6 and the top wall of the conical nut 4-2 can be changed by changing the semicircular truncated body 6- 1. Adjust the bottom surface radius r ₁ in 6-2, i.e. h ₁ =tan80°×(r ₁ -25)-h ₂ , h ₂ is the distance between the top wall of the conical nut and the top wall of the upper flange of the steel beam, the smaller h ₁ is The greater the rigidity and bearing capacity of the bolted shear connector; the preferred thickness of the precast concrete plate 8 is 150mm, that is, the height of the reserved hole 9 is 150mm, and the preferred height of the insert 6 is H=100mm.

In the described shear bolt set, the conical nut 4-2 needs to be processed in the factory to _an α1 inclination angle as shown in Figure 4. In order to facilitate the processing of the flange hole of the steel beam and the connection of the composite beam, the preferred The angle α ₁ = 60° between the cone busbar of the conical nut 4-2 and the top wall of the upper flange of the steel beam; during the assembly process, a lower threaded rod section 3 that is higher than the upper surface of the conical nut 4-2 is reserved , as the necked rod section, the preferred height of the necked rod section is 5mm.

The installation process of this structure is as follows: as shown in Figure 5, after the precast concrete slab 8 is hoisted on the upper flange 7 of the I-shaped steel beam 10, the screw connection holes 6-4 and 6-5 in the insert block 6 are respectively aligned with each other. The upper part of the two double-ended studs in the tapered holes of the upper flange 7 of the quasi-I-shaped steel beam 10, as shown in Figure 3, the insert block 6 passes through the upper threaded rod section 1 and the smooth rod section 2 of the double-ended stud with The wall of the reserved hole 9 of the precast concrete plate 8 is tightly closed and cannot be shaken. The upper gasket 5-1 is fixed on the top wall of the insert block 6 by tightening the upper nut 4-1, and then torque is applied. The wrench tightens the upper nut 4-1 to apply pre-tension to the stud section located between the tapered nut 4-2 and the upper nut 4-1. Finally, as shown in FIG. 5 , the steel cover plate 11 is placed on the upper surface of the reserved hole 9 of the precast concrete plate, and the upper surface of the steel cover plate 9 is flush with the upper surface of the precast concrete plate 8 .

When the precast concrete slab 8 needs to be replaced, just unscrew the upper nut 4-1 of the shear bolt set, and take out the upper washer 5-1 and the insert, then the precast concrete slab 8 can be disassembled and replaced as a whole .

The specific implementation of the present invention is described above to facilitate the understanding and application of the present invention by those of ordinary skill in the technical field. However, it should be clear that those skilled in the art can easily make various modifications to the present invention and apply it to other embodiments without creative efforts. Therefore, the present invention is not limited to the specific embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (7)

1. A detachable steel-concrete composite beam with damage-free main material, comprising an I-shaped steel beam arranged in a horizontal direction, a prefabricated concrete slab is supported on the upper flange of the I-shaped steel beam, and a The prefabricated concrete slab is spaced with a plurality of reserved holes at the front and back, and it is characterized in that: in each reserved hole, an insert block that matches the shape of the reserved hole is installed, and the top surface of the insert block is lower than The top surface of the reserved hole, the bottom surface of the insert block is higher than the bottom surface of the reserved hole, there are two screw connection holes spaced left and right on each insert block, and the I-shaped at the position corresponding to each screw connection hole A steel beam connecting hole is opened on the steel beam, the upper part of each said steel beam connecting hole is a tapered hole and the lower part is a circular hole with the same diameter as the bottom end of the tapered hole, and the top of the tapered hole is A conical nut is installed in the conical hole on the upper part of each steel beam connecting hole, the lower part of the conical nut matches the shape of the conical hole, and the top wall of the conical nut The top wall of the upper flange of the I-shaped steel beam is exposed; A double-ended stud is inserted into each screw connection hole, and the double-ended stud includes an upper threaded rod section, a smooth rod section and a lower threaded rod section connected in sequence from top to bottom; the double-ended stud The lower threaded rod section of the I-shaped steel beam is arranged through the corresponding conical nut, the steel beam connecting hole, the lower gasket and the lower nut in turn. The lower gasket is fixed on the bottom wall of the lower flange of the I-shaped steel beam by tightening the lower nut; and by tightening the lower nut, the conical nut is tightly fitted and fixed on the conical shape of the I-shaped steel beam on the wall of the hole; the upper part of the stud is covered with an upper gasket and screwed with an upper nut, and the upper gasket is fixed on the top wall of the insert block by tightening the upper nut; The upper threaded rod section and the smooth rod section of the head stud are arranged in the screw connection hole of the insert block; in each reserved hole, a steel cover plate supported on the double-ended stud is installed, and the steel cover plate and the prefabricated The concrete slabs are fixed together, and the upper surface of the steel cover is flush with the upper surface of the precast concrete slab. 2 . The detachable steel-concrete composite beam with no damage to the main material according to claim 1 , wherein the generatrix of the tapered hole is 60° from the horizontal plane. 3 . 3. The detachable steel-concrete composite beam with no damage to the main material according to claim 1 or 2, characterized in that: a section of lower threaded rod section that is higher than the top wall of the conical nut and is located between the bottom surfaces of the insert blocks is used as a retractable section. The neck rod section, the cross-sectional area of the necked rod section is smaller than the cross-sectional area of the rest of the stud. 4 . The detachable steel-concrete composite beam with no damage to the main material according to claim 3 , wherein the height of the necked rod segment is 5 mm. 5 . 5. The detachable steel-concrete composite beam with damage-free main material according to claim 3, wherein the reserved hole is composed of a semicircular truncated body on both sides and a quadrangular prism in the middle; The body side plane is an isosceles trapezoid and is exactly the same as and coincides with the side surface of the quadrangular prism. _The semicircle radius of the bottom surface of the reserved hole is r ₂ =25mm. =80°. 6 . The detachable steel-concrete composite beam with damage-free main material according to claim 5 , wherein the distance between the bottom surface of the insert block and the top wall of the conical nut is h ₁ =tan80°×(r ₁ . 7 . -25)-h ₂ , h ₂ is the distance from the top wall of the conical nut to the top wall of the upper flange of the steel beam, and r ₁ is the radius of the bottom surface of the semicircular frustum on both sides. 7 . The detachable steel-concrete composite beam with no damage to the main material according to claim 6 , wherein the angle α ₁ =60° between the conical nut cone generatrix and the top wall of the upper flange of the steel beam. 8 .

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