Reinforced concrete slab composite beam with unequal height-to-diameter ratio shear connectors

Abstract

The utility model provides a kind of steel reinforced concrete slab composite beam using unequal height-diameter ratio bolt nail shear connector, including steel reinforced concrete bridge deck and steel beam connected by shear connector, the shear connector is cluster type bolt nail group, and the height-diameter ratio of bolt nail gradually decreases along transverse bridge direction, and the height-diameter ratio of cluster type bolt nail group is 5.6, 5, 4.8 respectively from left to right.The utility model uses unequal height-diameter ratio bolt nail to replace the uniform arrangement of traditional welding bolt nail, effectively improves the torsional stiffness of composite structure in the case of structure bearing eccentric load, reduces the overturning deformation of side span bridge under eccentric load, improves the stability of structure.

Description

Technical Field

[0001] This utility model relates to the field of engineering structure technology, specifically a reinforced concrete slab composite beam using unequal height-to-diameter ratio stud shear connectors. Background Technology

[0002] With the rapid development of the transportation industry, the grade and scale of bridge construction are constantly expanding. Modern bridges are increasingly inclined to adopt lightweight, large-span, high-strength, and durable design trends. Steel-concrete composite beams, which combine steel beams and concrete slabs through shear connectors, are a new type of structure that emerged after steel and concrete structures. They have advantages such as high load-bearing capacity, high stiffness and ductility, good seismic performance, low cost, and convenient construction, and are widely used in railway and highway bridges. This utility model studies the stress mechanism and failure mode of shear connectors in steel-concrete composite structures under eccentric loading, using eccentric loading as the load condition. It proposes a clustered stud connector distribution with unequal height-to-diameter ratios to further improve and apply the design to practical engineering, achieving better socio-economic benefits.

[0003] Existing technologies have yielded relatively comprehensive studies on the individual shear and pull-out properties of shear connectors, combining experimental and finite element simulation methods. Theoretical calculation formulas for shear connectors under different configurations have also been obtained and refined. However, in practical engineering, shear connectors are often subjected to complex stress states, including lateral bending moments and pull-out forces caused by repeated eccentric loads. Currently, there is limited research on the mechanical performance of shear connectors in composite bridges under these complex stress states, and there are no clear reference standards for the distribution of studded connectors under complex stress conditions. Utility Model Content

[0004] To address the problems of existing technologies, this invention provides a reinforced concrete slab composite beam using shear-resistant studs with unequal height-to-diameter ratios. By replacing the uniform arrangement of traditional welded studs with studs of unequal height-to-diameter ratios, the torsional stiffness of the composite structure is effectively improved under eccentric loads, reducing the overturning deformation of the side span bridge under eccentric loads and enhancing the stability of the structure.

[0005] This utility model provides a reinforced concrete slab composite beam using shear connectors with unequal height-to-diameter ratio studs, including a reinforced concrete bridge deck and a steel beam connected by shear connectors. The shear connectors are clustered stud groups, and the height-to-diameter ratio of the studs gradually decreases along the transverse direction of the bridge.

[0006] Further improvements were made, with the height-to-diameter ratios of the clustered studs from left to right being 5.6, 5, and 4.8, respectively. The clustered studs were arranged in 3×3 rows both longitudinally and transversely on the steel beam, with the transverse spacing being 4 times the average diameter of the stud group and the longitudinal spacing being 5 times the average diameter.

[0007] In a further improvement, the cluster of studs is fixed to the top plate of the steel beam by welding. It is pre-installed on the top plate of the I-beam, and then the steel beam is transported to the construction site for on-site pouring and assembly with the concrete slab.

[0008] In a further improvement, the steel beam is an I-beam, comprising an upper flange plate, a web plate, and a lower flange plate.

[0009] The beneficial effects of this utility model are as follows: 1. By using studs with unequal height-to-diameter ratios instead of the uniform arrangement of traditional welded studs, the torsional stiffness of the composite structure is effectively improved when the structure is subjected to eccentric loads. This reduces the overturning deformation of the side span bridge under eccentric loads and improves the stability of the structure.

[0010] 2. Replacing the uniform arrangement of traditional welded studs with studs of unequal height-to-diameter ratio can effectively improve the interface anti-slip capability of steel-concrete composite beam connectors. 3. Group studs are arranged in the transverse position of the bridge according to the height-to-diameter ratio from large to small. This optimizes the utilization rate of the single stud bearing capacity within the stud group, improves the failure area of ​​the concrete slab, and thus makes reasonable use of the group stud effect to enhance the shear bearing capacity of the group studs and the overall stiffness of the structure.

[0011] 4. The studs can be welded in the factory in advance, reducing on-site construction time and improving construction efficiency. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a cross-sectional view of the present invention under eccentric loading.

[0014] Figure 2 This is a top view of the present invention under eccentric loading.

[0015] Figure 3 This is a schematic diagram of the load conditions under eccentric loading of this utility model.

[0016] Figure 4 This is a schematic diagram illustrating the force mechanism analysis of the stud connector along the stud height direction under eccentric loading.

[0017] Figure 5Comparative contour maps of stress distribution in the concrete slab of a steel-concrete composite beam using clustered stud connectors with equal height-to-diameter ratio under eccentric loading.

[0018] Figure 6 This is a comparative cloud map of the stress distribution of concrete under eccentric loading using this utility model.

[0019] Figure 7 The stress variation curves are caused by the distance between the clustered stud connectors with unequal height-to-diameter ratios and the loading point.

[0020] Figure 8 The stress variation curve is caused by the distance between the clustered stud connector with equal height-to-diameter ratio and the loading point. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0022] like Figure 1 as well as Figure 2 As shown, the present invention discloses a reinforced concrete slab composite beam using stud shear connectors with unequal height-to-diameter ratios, comprising a cast-in-place reinforced concrete bridge deck 1, stud shear connectors with unequal height-to-diameter ratios 2, an I-beam 3, and concrete pads 5 added for applying loads. The cast-in-place reinforced concrete deck consists of a reinforcing cage 4 with internal binding and cast-in-place concrete 1. The stud connectors with unequal height-to-diameter ratios 2 include three sets of stud connectors with height-to-diameter ratios of 6.92, 6.15, and 5.27, which are welded together in 3×3 rows on the top flange of the I-beam 3. The transverse spacing is four times the average diameter of the stud group, and the longitudinal spacing is five times the average diameter.

[0023] like Figure 3 and Figure 4As shown, the force mechanism of the stud under eccentric loading is analyzed. Under the action of lateral eccentric load P, in order to coordinate the vertical deformation of the concrete slab and the steel beam, the stud is subjected to the lifting effect of the concrete slab, generating a vertical pull-out force C, which is transmitted diagonally downward from the stud head along both sides to E and F. Near the root of the stud on the left side, a force is applied at an angle β to the concrete, and the horizontal component D generated by the diagonal force on the right side provides an additional contribution to the frictional capacity of the steel-concrete surface, causing separation of the stud root from the concrete. As the concrete at the root is crushed, its transmitted horizontal component A is relatively reduced, and will be transmitted to the stud from the concrete above the stud root. Ultimately, under the combined action of shear stress and pull-out stress, failure is expected to occur directly at the stud root.

[0024] Finite element stress analysis was performed on the stud arrangements with equal and unequal height-to-diameter ratios under eccentric load P proposed in this utility model. The stress distribution of the concrete slab in the steel-concrete composite beam is shown below. Figure 5 and Figure 6 As shown. By comparing the stress contour diagrams of the concrete slab in group-nail connectors with equal and unequal height-to-diameter ratios, it can be found that... Figure 6 The stress distribution of a concrete slab with a uniform height-to-diameter ratio is such that the maximum stress is concentrated in the middle of the slab. The present invention, using a concrete slab with a unequal height-to-diameter ratio arrangement, exhibits a saddle-shaped stress distribution, with lower stress at the sides and middle, and the maximum stress is significantly reduced compared to the uniform height-to-diameter ratio stud group. This invention improves the location and failure mode of the maximum stress in the concrete slab by adjusting the height-to-diameter ratio, increases the utilization rate of the shear bearing capacity of the stud rows on both sides of the concrete slab-steel beam interface, and makes the stud group effect distribution more rational.

[0025] Figure 7 and Figure 8 By comparing the changes in maximum tensile and compressive forces on studs with varying height-to-diameter ratios and distances from the eccentric loading position, it can be observed that the stress distribution within the stud group connector is not uniform. The tensile force initially increases and then decreases with increasing distance from the eccentric loading position, while the outermost stud experiences compressive force. Based on different stress patterns, this invention employs stud height-to-diameter ratios corresponding to the appropriate ratios, effectively improving the average shear capacity of the stud group connector and enhancing the utilization efficiency of the shear capacity within the stud group. Example

[0026] To investigate the mechanical properties of the studded connector with unequal height-to-diameter ratio proposed in this invention under eccentric loading, multiple finite element models were fabricated and compared with the European EC-4 standard. The studded groups with and without unequal height-to-diameter ratios were arranged in 3×3 rows both longitudinally and transversely on the I-beam, with the transverse spacing being 4 times the average diameter of the stud group and the longitudinal spacing being 5 times the average diameter. The stud dimensions (height × diameter) used in the unequal height-to-diameter ratio stud groups from left to right were ∅90mm×13mm, ∅80mm×13mm, and ∅95mm×18mm, while the stud dimensions used in the equal height-to-diameter ratio stud groups were ∅80mm×13mm. The concrete used was C50, and all sections were reinforced with HRB335 steel bars, with vertical bars and stirrups having diameters of 16mm and 8mm, respectively. The I-beam was made of Q345 steel, with dimensions of 350mm×200mm×20mm. The loading method is displacement loading, using a pad block loaded onto the concrete slab. A finite element model diagram is shown below. Figure 2 As shown.

[0027] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of this utility model. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this utility model, without departing from the principle of this utility model, should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A reinforced concrete slab composite beam employing shear connectors with unequal height-to-diameter ratio studs, comprising a reinforced concrete bridge deck and a steel beam connected by shear connectors, characterized in that: The shear connector is a cluster of studs, with the height-to-diameter ratio of the studs gradually decreasing along the transverse direction of the bridge.

2. The reinforced concrete slab composite beam with unequal height-to-diameter ratio stud shear connectors according to claim 1, characterized in that: The height-to-diameter ratios of the clustered stud groups from left to right are 5.6, 5, and 4.8, respectively.

3. The reinforced concrete slab composite beam with unequal height-to-diameter ratio stud shear connectors as described in claim 1 or 2, characterized in that: The clustered studs are arranged in 3×3 rows on the steel beam, with the transverse spacing being 4 times the average diameter of the stud group and the longitudinal spacing being 5 times the average diameter.

4. The reinforced concrete slab composite beam with unequal height-to-diameter ratio stud shear connectors as described in claim 1, characterized in that: The cluster of studs is fixed to the top plate of the steel beam by welding.

5. The reinforced concrete slab composite beam with unequal height-to-diameter ratio stud shear connectors according to claim 1, characterized in that: The steel beam is an I-beam, comprising an upper flange plate, a web plate, and a lower flange plate.

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