Flexible shear-resistant structure for connecting steel beam and concrete slab
Technical Field
The utility model relates to a connecting elements of steel and concrete, more specifically say, relate to a flexible shear structure of connecting girder steel and concrete slab.
Background
The overall performance of the beam-slab structure of the steel structure building depends on two factors, namely the mechanical property formed by the combined action of the steel beam and the floor slab, the relative deformation resistance between the steel beam and the floor slab, and the interaction of the two factors. The common forms of the beam-slab structure of the steel structure building in the existing market are a steel beam-template concrete floor structure, a steel beam-composite floor (also called a steel floor deck) structure and a steel beam-composite floor (also called a truss floor deck) structure. The steel beam-template concrete floor structure has good common stress performance and strong relative deformation resistance, and has the defects of large field construction amount and low industrialization degree; the common stress performance and the relative deformation resistance of the steel beam-composite floor structure are low, the industrialization degree is high, but the engineering cost is high; the common stress performance and the relative deformation resistance of the steel beam-composite floor slab are close to those of a template concrete structure, the industrialization degree is high, the construction is convenient, and the comprehensive cost is low.
The above three main structural forms only depend on the inherent longitudinal resistance to relative deformation of the beam plates, and are difficult to satisfy the overall structural performance requirements, so that the shear connector structural measures such as studs are added to improve the longitudinal shear resistance between the beam plates, and the additional structural measures are used to further improve the integrity between the steel beam and the floor slab (namely, the vertical lifting effect between the concrete slab and the steel beam is resisted).
The structure of resisting the longitudinal shear force between the beam slab divides into two main categories of rigidity and flexibility, and the flexible construction is obviously better than the rigidity, and the reason and the foundation that adopt the shear bolt nail structure in the actual engineering application at present are: (1) the shear-resistant stud resists the strong horizontal shear force at the interface of the steel beam and the concrete and can prevent relative horizontal sliding; (2) the big round heads of the shear-resistant studs can play a certain role in limiting the separation of the concrete floor; (3) the shear-resistant stud has good stress performance, the stud is isotropic, and the strength and the rigidity in any direction are the same; (4) the shear resistant stud is manufactured without large-scale equipment, has simple process and is suitable for industrial production; (5) the shear resistant stud is convenient for construction and has little influence on the reinforcing bars of the floor slab; however, since the shear studs are independent of each other and have dispersed functions, it is actually difficult to truly exert the technical advantages, and the conventional engineering applications adopt shear connectors designed to exert functions independently, so that the following problems exist: (1) the common action stress of the steel beam and the floor slab needs to be realized by the integrity and the cooperation of the structure, the shear resistant stud is used for resisting the horizontal shear force at the interface of the steel beam and the concrete, the relative horizontal slippage is prevented, and the structure stress can only be used as the supplement of the structure stress, so that the shear resistant stud is applied to the steel beam-composite floor slab structure, has better auxiliary stress performance and technical advantages, but has certain technical redundancy in the aspects of the steel beam-template concrete floor slab structure and the steel beam-composite floor slab structure; (2) the shear-resistant stud has a limited effect of limiting the separation of the concrete floor slab by the large round head, and the local extrusion damage of the concrete slab is easily generated; (3) because the longitudinal shear design between the beam plates does not relate to the consideration of the out-of-plane stability, the strength and rigidity of the studs are excessively large, so that economic and technical waste is easily caused, and the studs distributed at a certain density have different degrees of segmentation influence on the concrete floor, so that the overall safety performance of the beam plate structure is not facilitated; (4) the shear resistant stud is suitable for industrial production, large-scale equipment is not required for manufacturing, and although the production process is simple, the use cost is high; (5) the shear resistant studs have little influence on the reinforcing bars of the floor slab, but need to be constructed by adopting special equipment.
Chinese patent, publication number: CN101446113A, published: in 2009, 6/3, a method for combining a post-added steel beam and a concrete slab is disclosed, and firstly, the positions of the post-added steel beam and a connecting steel plate are determined on the bottom surface of an established concrete slab; secondly, anchoring a post-anchoring building anchor bolt into the built concrete slab at the position of the connecting steel plate; then, fixing the connecting steel plate on the bottom surface of the built concrete slab by using a post-anchoring building anchor bolt; and finally, connecting the rear additional steel beam with the connecting steel plate. The invention adopts the post-anchored building anchor bolt to bear the longitudinal shearing force between the superposed surfaces of the steel beam and the reinforced concrete slab and limit the relative sliding of the steel beam and the reinforced concrete slab, so that the steel beam and the reinforced concrete slab can be combined into a whole and reliably work together. The disadvantages are as follows: the construction is troublesome, and the anchor bars added later are easy to collide with the existing steel bars in the plate when being anchored, so that the anchor bars can be shifted or break the steel bars in the plate.
Chinese invention patent, application number: 201110227606.5, filing date: 2011.08.09 discloses a combined beam component, which comprises a steel beam, a concrete slab, a bolt, a splice plate and a steel bar, wherein the steel beam is an I-shaped steel beam, the concrete slab is arranged on the top of the steel beam, the bolt is arranged on the top of the steel beam, the upper part of the bolt is embedded into the concrete slab, the splice plate is arranged on the steel beam, and the steel bar is inserted into the splice plate. The disadvantages are that: the function of the bolt is similar to that of the shear-resistant stud in the prior art, the bolt is suitable for industrial production, large-scale equipment is not needed in manufacturing, the production process is simple, but the use cost is high; and the splice plates need to be assembled, so that the composite beam member is troublesome to manufacture and takes time.
Disclosure of Invention
1. Technical problem to be solved
The invention provides a flexible shear structure for connecting a steel beam and a concrete slab, aiming at the problems that shear studs are independent from each other, dispersed in action, poor in shear effect, and capable of generating certain segmentation influence on the concrete slab, and not beneficial to the overall safety performance of a beam slab structure in the prior art, and a square steel tube connecting piece structure is not tightly connected with the concrete slab and cannot effectively form a whole. It can resist the longitudinal shearing force caused by different deformation between the steel beam and the concrete slab; and the integrity of the steel beam and the concrete slab is improved through the hooping effect of the twisted steel on the concrete.
2. Technical scheme
The purpose of the utility model is realized through the following technical scheme:
the flexible shear-resistant structure comprises a steel beam and shear-resistant threaded steel bars, wherein the shear-resistant threaded steel bars are welded on the steel beam along the longitudinal direction of an axis to form the flexible shear-resistant structure.
Preferably, the shear-thread steel bar comprises a horizontal section, an inclined section and a welding section, so that different processing areas of the shear-thread steel bar are determined, and the segmented processing of the shear-thread steel bar is facilitated.
Preferably, the beam width of the steel beam is less than or equal to 200mm, the shear-resistant twisted steel is a single-row bar, the shear-resistant twisted steel close to the edge of the steel beam has a distance d from the edge of the steel beam, and d is less than or equal to 100mm and is more than or equal to 50mm, and if a plurality of rows of bars are adopted, steel is wasted.
Preferably, the beam width of the steel beam is greater than 200mm, the shear-resistant twisted steel bars are a plurality of rows of bars, the shear-resistant twisted steel bars close to the edge of the steel beam are d away from the edge of the steel beam, d is greater than or equal to 50mm and less than or equal to 100mm, and if a single row of bars are adopted, stress is insufficient and the flexible shear-resistant effect cannot be achieved.
Preferably, the length of the inclined section of the shear-resistant reinforcing steel bar isWherein,
h=a-2b,
h is the height from the upper surface of the horizontal section to the lower surface of the welding section, a represents the thickness of the concrete plate, and b represents the thickness of the protective layer of the shear-resistant threaded steel bar. The basis and benefits of doing this are as follows: on one hand, the diameter of the hogging moment reinforcing steel bar of the concrete slab cannot exceed the thickness of the protective layer of the shear thread reinforcing steel bar, so that the shear thread reinforcing steel bar can be ensured to be positioned below the hogging moment reinforcing steel bar in the concrete slab to work and is not mutually influenced with the hogging moment reinforcing steel bar in the concrete slab, and if the shear thread reinforcing steel bar is positioned above the hogging moment reinforcing steel bar in the concrete slab to work, the protective layer is lacked; on the other hand, the selection is the best solution, taking the above factors into full consideration, namely, the shear resisting effect and the concrete tightening effect are exerted to the maximum extent.
Preferably, the shear-resistant twisted steel is welded on the steel beam, the length of the welding section is L, and when single-side welding is used, L is 10 times of the diameter of the shear-resistant twisted steel; when double-sided welding is used, L is 5 times the diameter of the shear-threaded bar, which is to comply with the regulations of J GJ18-2003 "bar welding and acceptance rules".
3. Advantageous effects
Compared with the prior art, the utility model has the advantages of:
(1) the shearing resistant twisted steel of the utility model has the same type selection as the main stressed steel bar of the concrete slab, thus reducing the manufacturing cost of the flexible shearing resistant structure and being easy to manufacture; the main stressed steel bars of the concrete slab comprise slab bottom steel bars and negative moment steel bars, after the specification and the material of the main stressed steel bars of the concrete slab are determined, shear-resistant twisted steel bars with the same specification and the same material as the main stressed steel bars of the concrete slab are selected, and the shear force of the shear-resistant twisted steel bars does not exceed the tensile yield strength of the steel bars and has larger margin, so that the dispersed stress of the main stressed steel bars of the concrete slab can be changed into integral stress, the synergistic effect of the steel beams and the concrete slab is enhanced, and the integrity of the steel beams and the structure of the concrete slab is improved;
(2) when the beam width of the steel beam is less than or equal to 200mm, the shear-resistant twisted steel is a single-row bar, the shear-resistant twisted steel is close to the edge of the steel beam, the distance from the edge of the steel beam is d, d is less than or equal to 50mm and less than or equal to 100mm, and if a plurality of rows of bars are adopted, steel is wasted; when the beam width of the steel beam is greater than 200mm, the shear-resistant twisted steel bars are a plurality of rows of bars, the shear-resistant twisted steel bars close to the edge of the steel beam are at a distance d from the edge of the steel beam, d is not less than 50mm and not more than 100mm, if a single row of bars are adopted, the stress is insufficient, and the flexible shear-resistant effect cannot be achieved;
(3) the utility model discloses oblique section of twisted steel bar shearsHas a length ofWherein,
h=a-2b,
h is the height from the upper surface of the horizontal section to the lower surface of the welding section, a represents the thickness of a concrete plate, and b represents the thickness of a protective layer of the shear-resistant threaded steel bar, and the basis and the advantages of the method are as follows: on one hand, the diameter of the hogging moment reinforcing steel bar of the concrete slab cannot exceed the thickness of the protective layer of the shear thread reinforcing steel bar, so that the shear thread reinforcing steel bar can be ensured to be positioned below the hogging moment reinforcing steel bar in the concrete slab to work and is not mutually influenced with the hogging moment reinforcing steel bar in the concrete slab, and if the shear thread reinforcing steel bar is positioned above the hogging moment reinforcing steel bar in the concrete slab to work, the protective layer is lacked; on the other hand, under the condition of fully considering the factors, the selection is the best proposal, namely, the shearing resistance effect and the concrete tightening effect are exerted to the maximum extent;
(4) the utility model is welded on the steel beam, the length of the welding section is L, when using single-side welding, L is 10 times of the diameter of the shear-resistant screw-thread steel bar; when double-sided welding is used, L is 5 times the diameter of the shear-threaded steel bar, so as to meet the regulation of J GJ18-2003 Reinforcement welding and acceptance Specifications;
(5) the utility model uses the shear resistant screw thread steel bar as the shear connector, which can be simply and evenly arranged along the whole steel beam total length or the subsection, thus being beneficial to the longitudinal redistribution of the shear force in the steel beam and concrete slab composite structure and leading the characteristic of the flexible structure to be more obvious;
(6) the utility model discloses a shear-resistant twisted steel bar includes horizontal segment, oblique section and welding segment, has confirmed shear-resistant twisted steel bar's different processing region like this, is convenient for to shear-resistant twisted steel bar segmentation processing.
Drawings
FIG. 1 is a schematic view of the flexible shear structure of the present invention;
FIG. 2 is a schematic view of the flexible shear structure processing calculation of the present invention;
FIG. 3 is a cross-sectional view of a plurality of rows of ribs of the flexible shear structure of the present invention;
fig. 4 is the cross section schematic diagram of the single-row rib of the flexible shear structure of the present invention.
The reference numbers in the figures illustrate: 1. a steel beam; 2. shear-resistant twisted steel; 21. a horizontal segment; 22. an oblique section; 23. welding a section; 3. and (7) welding points.
Detailed Description
The invention is described in detail below with reference to the drawings and specific examples.
Example 1
A flexible shear structure for connecting a steel beam and a concrete slab is combined with figures 1, 2, 3 and 4, and comprises the steel beam 1 and shear-resistant threaded steel bars 2, wherein the shear-resistant threaded steel bars 2 are welded on the steel beam 1 along the longitudinal direction of an axis to form the flexible shear structure.
The shear-resistant reinforcing steel bar 2 comprises a horizontal section 21, an inclined section 22 and a welding section 23, so that different processing areas of the shear-resistant reinforcing steel bar 2 are determined, and the shear-resistant reinforcing steel bar 2 can be processed in a segmented manner. The row number of the shear-resistant twisted steel bars 2 is determined according to the width of the steel beam, and the too wide or too dense width of the steel beam mainly weakens the effect of hooping or hooping concrete. When the beam width of the steel beam 1 is less than or equal to 200mm, the shear-resistant twisted steel 2 is a single-row rib, and if a plurality of rows of ribs are adopted, steel materials are wasted; as shown in FIG. 4, the distance d from the shear-resistant twisted steel 2 close to the edge of the steel beam 1 is greater than or equal to 50mm and less than or equal to 100 mm. When the beam width of the steel beam 1 is more than 200mm, the shear-resistant twisted steel 2 is a plurality of rows of ribs, if a single row of ribs is adopted, the stress is insufficient, and the flexible shear-resistant effect cannot be achieved; as shown in figure 3, the distance between the shear-resistant twisted steel 2 close to the edge of the steel beam 1 and the edge of the steel beam 1 is d, and d is more than or equal to 50mm and less than or equal to 100 mm.
The length of the oblique segment 22 of the shear-resistant reinforcing bar 2 isWherein,
h=a-2b,
h is the height from the lower surface of the welding section 23 to the upper surface of the horizontal section 21, a represents the thickness of the concrete slab, and b represents the thickness of the protective layer of the shear-threaded steel bar 2. The basis and benefits of doing this are as follows: on one hand, the diameter of the hogging moment reinforcing steel bar of the concrete slab cannot exceed the thickness of the protective layer of the shear resistant threaded reinforcing steel bar 2, so that the shear resistant threaded reinforcing steel bar 2 can be ensured to be positioned below the hogging moment reinforcing steel bar in the concrete slab to work and is not mutually influenced with the hogging moment reinforcing steel bar in the concrete slab, and if the shear resistant threaded reinforcing steel bar 2 is positioned above the hogging moment reinforcing steel bar in the concrete slab to work, the thickness of the protective layer of the shear resistant threaded reinforcing steel; on the other hand, this option is the best solution, taking into full account the above factors, i.e. exerting both the shear-resisting action and the maximum tightening action on the concrete.
The shear-resistant threaded steel bar 2 is welded on the steel beam 1 to form a welding spot 3, the length of the welding section 23 is L, and when single-side welding is used, the L is 10 times of the diameter of the shear-resistant threaded steel bar 2; when double-sided welding is used, L is 5 times the diameter of the shear-threaded bar 2 and the length of the horizontal section 21 is 2L, which is set to comply with the regulations of J GJ18-2003 "bar welding and acceptance rules".
The type selection of the shear-resistant twisted steel 2 is the same as that of the main stressed steel of the concrete slab, so that the manufacturing cost of the flexible shear-resistant structure is reduced, and the flexible shear-resistant structure is easy to manufacture; the main stressed steel bar of the concrete slab comprises a slab bottom steel bar and a hogging moment steel bar, after the specification and the material type of the main stressed steel bar of the concrete slab are determined, the shear-resistant twisted steel bar 2 which has the same specification and the same material as the main stressed steel bar of the concrete slab is selected, the shear force of the shear-resistant twisted steel bar can not exceed the tensile yield strength of the steel bar and has larger margin, so that the dispersed stress of the main stressed steel bar of the concrete slab can be changed into integral stress, the synergistic effect of the steel beam 1 and the concrete slab is enhanced, and the integrity of the steel beam 1 and the concrete slab structure is improved.
The utility model relates to a connection strengthening problem of a steel beam and a concrete slab, which is the supplement and improvement of the original structure, and the importance of the connection strengthening problem gradually appears along with the invention and innovation of a novel beam slab structure form. Such as steel beam-composite floor structures, are more suitable for use with structures whose common stress performance and resistance to relative deformation will approach, or even exceed, that of the formwork concrete structure. The self weight of the concrete floor slab at the construction stage is completely born by the steel bars, tensile stress is not generated in the concrete after the construction is finished, after the structure enters the use stage, the tensile stress of the concrete in the negative bending moment area and the positive bending moment area is obviously reduced, the crack width of the concrete is obviously reduced compared with that of a template concrete structure, the industrialization degree of the truss type floor slab structure is high, the construction is convenient, the comprehensive cost is low, and the truss type floor slab structure is obviously superior to a steel beam-template concrete structure and a steel beam-composite floor slab structure, so that the flexible shear-resistant structure of the deformed steel bars is applied to the steel beam-template concrete structure and the steel beam-composite floor slab structure.
Example 2
In order to improve the integrity of a steel beam and concrete plate structure in a certain construction site, a flexible shear structure for connecting the steel beam and the concrete plate is provided, wherein for the condition that the beam width of the steel beam 1 is less than or equal to 200mm, a single row of ribs are selected for the shear-resistant twisted steel 2, and the distance d between the single row of ribs and the edge of the steel beam 1 is 50 mm; for the condition that the beam width of the steel beam 1 is more than 200mm, the shear-resistant threaded steel bar 2 adopts a plurality of rows of ribs, the distance d between the plurality of rows of ribs and the edge of the steel beam 1 is 50mm, single-side welding is used, the length of the welding section 23 is L, and L is 10 times of the diameter of the shear-resistant threaded steel bar 2; the rest is the same as example 1.
Example 3
In order to enhance the synergistic effect between a steel beam and a concrete plate structure and improve the integrity between the steel beam and the concrete plate structure by a certain construction crew, a flexible shear structure for connecting the steel beam and the concrete plate is provided, wherein under the condition that the beam width of the steel beam 1 is less than or equal to 200mm, a single row of ribs are selected for the shear-resistant twisted steel 2, and the distance d between the single row of ribs and the edge of the steel beam 1 is 100 mm; for the condition that the beam width of the steel beam 1 is more than 200mm, the shear-resistant threaded steel bar 2 adopts a plurality of rows of ribs, the distance d between the plurality of rows of ribs and the edge of the steel beam 1 is 100mm, when double-sided welding is used, the length of the welding section 23 is L, and L is 5 times of the diameter of the shear-resistant threaded steel bar 2; the rest is the same as example 1.
The invention and its embodiments have been described above schematically, and the actual technical solution is not limited to them. Therefore, if a person skilled in the art were to be informed by the teachings of the present invention, the person could not creatively design an embodiment similar to the above-mentioned solution without departing from the spirit of the present invention, and shall fall within the protection scope of the present patent.