A bridge frame pier-tied beam joint with a compressible bendable steel plate

Abstract

This invention relates to the field of bridge engineering technology, and discloses a bridge pier-tie beam node with a compressible bendable steel plate. Located at the intersection of the pier and tie beam, it includes a weakened tie beam located at the end of the tie beam facing the pier, with a cross-sectional height smaller than that of the tie beam. Compressible bendable steel plate assemblies are located above and below the weakened tie beam, and buckling-resistant cover plate assemblies respectively clamp the upper and lower bendable steel plate assemblies. The two ends of the upper and lower bendable steel plate assemblies are fixedly connected to the pier and tie beam, respectively. The bendable steel plate assembly of this invention exhibits "secondary yielding" characteristics under both tension and compression; it also features a "weak-to-strong" characteristic and large deformation capacity. Combined with the relatively low stiffness of the weakened tie beam cross-section, this allows the pier under seismic loading to form a "strong column, weak beam" failure mode, controlling the location of the damage plastic hinge at the plastic energy dissipation node.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering, and more particularly to a bridge frame pier-tie beam joint with a compressible bendable steel plate. Background Technology

[0002] With the development of society and the economy, bridges, as important structures that can cross rivers, valleys, and other complex terrains, play a vital role in my country's transportation network, especially in the western regions prone to high-intensity earthquakes. Currently, to ensure that bridges remain passable after an E1 earthquake or can be quickly restored to traffic after an E2 earthquake, it is of great significance to install energy-dissipating devices in the bridge structure that can control earthquake damage and be quickly replaced after an earthquake.

[0003] The frame pier is a common substructure of highway bridges. Under seismic loading, the beam-end region of the pier-tie beam joint is subjected to a complex stress state under bending moment, shear force, and axial force, making it prone to failure. This leads to reduced bridge ductility and, in severe cases, collapse. Reducing the stiffness of the tie beam ends—specifically, decreasing the tie beam section height in this region and installing a special energy-dissipating device—effectively controls the transfer of plastic hinge positions to the tie beam ends, preventing damage to the pier structure and improving the seismic performance of the frame pier. However, traditional methods of reducing tie beam stiffness still have some drawbacks. For example, weakening the tie beam may create weak points in the rest of the structure, reducing its resistance to progressive collapse. Summary of the Invention

[0004] To ensure that the core area of ​​the bridge pier-tie beam joint is protected from damage, improve the seismic performance of the bridge, and achieve controllable earthquake damage and rapid post-earthquake recovery, the present invention aims to provide a bridge pier-tie beam joint with a compressible bendable steel plate.

[0005] This invention provides the following technical solution:

[0006] A bridge frame pier-tie beam node with a compressible bendable steel plate is provided at the intersection of the pier (1) and the tie beam (2). It includes a weakened tie beam (3) located at the connection end of the tie beam (2) toward the pier (1), the cross-sectional height of the weakened tie beam (3) being smaller than the cross-sectional height of the tie beam (2); a compressible bendable steel plate assembly (4) is located on the upper and lower sides of the weakened tie beam (3), and a buckling-resistant cover plate assembly (5) is fixedly clamped on the upper and lower sides of the bendable steel plate assembly (4); the two ends of the upper and lower sides of the bendable steel plate assembly (4) are fixedly connected to the pier (1) and the tie beam (2) respectively.

[0007] According to some embodiments, a single bent steel plate assembly (4) includes a bent steel plate and two L-shaped pressure plates (7). The bent steel plate has an elastic bending portion, and the two ends of the bending portion are respectively fixedly connected to the two L-shaped pressure plates (7) in the horizontal direction. The two L-shaped pressure plates (7) are respectively fixedly connected to the pier column (1) and the tie beam (2). The cover plate assembly (5) includes an upper cover plate and a lower cover plate that clamp the middle cover plate. The middle cover plate consists of two pieces in the front-back direction and is located on both sides of the L-shaped pressure plate (7). The upper and lower cover plates clamp the middle cover plate and are fixed by bolts. An opening is provided in the upper cover plate at the bending position corresponding to the bending of the bent steel plate.

[0008] According to some embodiments, the bent steel plate is a first bent steel plate (6), which includes an outwardly protruding bent portion and extension portions at both ends of the bent portion. The extension portions are horizontally attached and fixedly connected to two L-shaped pressure steel plates (7) in the direction of the weakening tie beam (3).

[0009] According to some embodiments, the bent steel plate is a second bent steel plate (9), the second bent steel plate (9) includes an outwardly protruding bent portion, the two ends of the bent portion are fixedly connected to the two inward ends of the two L-shaped pressure steel plates (7); the second bent steel plate (9) is provided with pressure wing plates (10) on both sides, the pressure wing plates (10) are fixedly connected to the two inward ends of the two L-shaped pressure steel plates (7), extend horizontally inward and are spaced a certain distance apart.

[0010] According to some embodiments, the cross-sectional width of the L-shaped pressure plate (7) is greater than the cross-sectional width of the first bent steel plate (6).

[0011] According to some embodiments, the shape of the bent portion is triangular or arc-shaped.

[0012] According to some embodiments, the bends of the bending portion are all provided with chamfers.

[0013] According to some implementation methods, the pier (1) and the tie beam (2) are connected to the L-shaped pressure steel plate (7) by pre-embedded high-strength threaded rods.

[0014] According to some implementations, the longitudinal bars in the weakening tie beam (3) are bent upwards and downwards respectively to form diagonal reinforcing bars (8).

[0015] According to some embodiments, the weakening tie beam (3) is provided with denser stirrups.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Under seismic loading, the pier-tied beam joint of the frame pier will generate large bending moments and shear forces. After decoupling the bending moment and shear force, ideally, the bent steel plates arranged on the upper and lower sides of the tied beam will bear the axial tensile force generated by the decoupling of the bending moment at the beam end, and the weakened concrete section of the tied beam will bear the shear force generated by the decoupling. The bent steel plate assembly provided by this invention has the characteristic of "secondary yielding" under both tension and compression. When the bent steel plate assembly is under tension, the bending point of the bent steel plate enters the plastic stage from the elastic stage, and the first yielding occurs, followed by the yield strengthening stage; when the bent steel plate is straightened, the second yielding occurs, and then the load limit point is reached. When the bent steel plate assembly is under compression, the first yield point is the same as under tension, both occurring at the bend where the steel plate enters the plastic stage. The second yield point occurs as the displacement at the plate end increases, with contact compression on one side of the L-shaped compression steel plate increasing the load-bearing capacity. Furthermore, the correspondence between the "secondary yield points" under tension and compression can be achieved by adjusting the distance of the straight segments of the L-shaped compression steel plate. The ultimate bearing capacity of the L-shaped compression steel plate is the ultimate load point of the bent steel plate assembly. The bent steel plate assembly exhibits characteristics of "weak at first, strong later" and large deformation capacity. Combined with the relatively low stiffness of the weakened tie beam section, it can create a "strong column, weak beam" failure mode for the frame pier under seismic loading, controlling the location of the damage plastic hinge at the plastic energy dissipation node. Simultaneously, under large displacement, the bent steel plate provides significant load-bearing capacity, offering resistance to progressive collapse and protecting the frame pier structural system from damage.

[0018] Although traditional bent steel plate members have excellent tensile properties, their ultimate compressive bearing capacity is only equivalent to the first yield bearing capacity of bent steel plate under tension. As a result, the weakened tie beam section will bear part of the axial pressure generated by the decoupling of the section bending moment, which puts the weakened tie beam section in a complex stress state and has an adverse effect on the section bearing capacity.

[0019] The second yield point of the compressible bending steel plate assembly designed in this invention is achieved by the following method: the L-shaped compression steel plate, which is welded to the bending steel plate, slides in the buckling-resistance cover plate assembly to prevent the second-order effect caused by the compression of the bending steel plate. This causes the L-shaped compression steel plate ends on both sides of the bending section to contact and compress, providing a higher compressive bearing capacity, which matches the tensile bearing capacity of the bending steel plate. This allows the weakened tie beam section to mainly bear the shear force generated by the section.

[0020] In response to the stress mechanism of this type of node, this invention designs oblique reinforcing bars 8 by bending the longitudinal steel bars on the upper and lower sides downwards and upwards respectively in the weakened tie beam section. Compared with the traditional weakened section reinforcement, the oblique reinforcing bars can improve the shear bearing capacity, but do not improve the bending performance, which is conducive to achieving bending-shear separation.

[0021] Meanwhile, the compressible bending steel plate assembly can be bolted to high-strength threaded rods pre-embedded in the piers and tie beams via only one side of the L-shaped compressible steel plate, allowing for post-earthquake replacement. As the primary replaceable energy-dissipating and damping component, the compressible bending steel plate assembly will undergo significant plastic deformation under seismic loading. Plastic development mainly occurs at the bends of the bending steel plates, thus controlling the location of plastic hinges in the nodal area. The connection between potentially damaged bending steel plate assemblies and the piers and tie beams is bolted, facilitating rapid replacement after earthquake damage. This saves significant time, labor, and maintenance costs, and promotes the rapid restoration of traffic flow after an earthquake. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the location of the bridge frame pier-tie beam node with a compressible bendable steel plate provided in Embodiment 1 or Embodiment 2 of the present invention;

[0023] Figure 2 This is a structural schematic diagram of a bridge frame pier-tie beam node with a compressible bendable steel plate provided in Embodiment 1 or Embodiment 2 of the present invention;

[0024] Figure 3 This is a schematic diagram of the internal reinforcement structure of the weakened tie beam 3 provided in Embodiment 1 or Embodiment 2 of the present invention;

[0025] Figure 4 This is an assembly diagram of the first bent steel plate and cover plate assembly provided in Embodiment 1 of the present invention;

[0026] Figure 5 This is a schematic diagram of the combined and disassembled states of the cover plate assembly provided in Embodiment 1 of the present invention.

[0027] Figure 6 This is a schematic diagram of the structure and assembly of the first bent steel plate in the bent steel plate assembly provided in Embodiment 1 of the present invention.

[0028] Figure 7 This is a schematic diagram of the structure and assembly of the second bent steel plate in the bent steel plate assembly provided in Embodiment 2 of the present invention.

[0029] In the picture:

[0030] 1. Pier column; 2. Tie beam; 3. Weakening tie beam; 4. Bending steel plate assembly; 5. Cover plate assembly; 6. First bending steel plate; 7. L-shaped compression steel plate; 8. Diagonal reinforcing bar; 9. Second bending steel plate; 10. Compression flange. Detailed Implementation

[0031] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "rear," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0033] The present invention will be further described below with reference to the accompanying drawings.

[0034] Example 1

[0035] like Figures 1 to 2 As shown, this embodiment provides a bridge frame pier-tie beam node with a compressible bendable steel plate, which is located at the intersection of pier 1 and tie beam 2. It includes: a weakened tie beam 3 located at the end of tie beam 2 facing pier 1, a compressible bendable steel plate assembly 4 located on the upper and lower sides of the weakened tie beam 3, and a buckling-resistant cover plate assembly 5 provided on the bendable steel plate assembly 4.

[0036] The weakened tie beam 3 reduces the cross-sectional height within a certain range at the beam end of the pier, thereby reducing the cross-sectional stiffness. Two bent steel plate assemblies 4, energy-dissipating components, are installed on the upper and lower sides of the weakened tie beam 3, respectively. Due to the early yielding and energy dissipation mechanism of the bent steel plate assemblies 4, and their lower initial stiffness, damage will preferentially occur at the newly designed energy-dissipating nodes, achieving the transfer of plastic hinges under seismic loading and the controllability of damage. Based on this moment-shear force decoupling mechanism, to increase the shear capacity of the weakened tie beam 3, the longitudinal reinforcement in the weakened tie beam 3 is bent upwards and downwards to form diagonal forked reinforcement 8, and the stirrups are densified, such as... Figure 3 .

[0037] like Figure 6 The pressure-bearing bent steel plate assembly 4 includes a first bent steel plate 6 and an L-shaped pressure-bearing steel plate 7. The left figure shows the first bent steel plate 6 welded to the L-shaped pressure-bearing steel plate 7, and the right figure shows the assembly in a separated state before welding. The first bent steel plate 6 is the main stress-bearing and energy-dissipating component. The bending shape in its middle is similar to a triangle or arc. Chamfers are made at each bending angle to prevent stress concentration. The bending shapes of the bent steel plate assemblies 4 located on the upper and lower sides of the weakening tie beam 3 are mirror-symmetrical with respect to the center of the tie section. One side of the L-shaped compression steel plate 7 is connected and fixed to the high-strength threaded rods embedded in the pier column 1 and tie beam 2 by bolts. The other side is welded to the straight sections on the left and right sides of the bending section of the first bending steel plate 6, respectively. This allows the bending steel plate assembly 4 to limit the vertical displacement of the L-shaped compression steel plate 7 when under pressure, thereby limiting the second-order effect generated by the first bending steel plate 6 under pressure. This ensures that, under large deformation, the plate ends of the two L-shaped compression steel plates 7 that are welded to the left and right sides of the bending section of the first bending steel plate 6 can make contact and squeeze, providing a certain compressive bearing capacity and reducing the adverse effects of weakening the stress in the section of the tie beam 3.

[0038] Figure 6 Compared to the first bent steel plate 6, the L-shaped compression steel plate 7 in the left figure has an increased cross-sectional width d on both its left and right sides. One side of the L-shaped compression steel plate 7 is connected to the pier column 1 and the tie beam 2 by bolts, and the other side is welded to the straight sections on the left and right sides of the bent section of the first bent steel plate 6.

[0039] like Figures 4-5 The cover plate assembly 5 for anti-bending is divided into three layers. Since the L-shaped compression steel plate 7 is wider than the first bending steel plate 6, the upper and lower layers of the cover plate assembly 5 can clamp the part of the L-shaped compression steel plate 7 that extends beyond the first bending steel plate 6 to limit the vertical displacement of the L-shaped compression steel plate 7. The middle layer cover plate is mainly used to facilitate the fixing of the upper and lower layer cover plates with bolts. Figure 5 The left image shows the combined state, and the right image shows the split state.

[0040] This embodiment utilizes energy-dissipating devices installed within a certain range at the ends of the pier tie beams to achieve sufficient stiffness and load-bearing capacity under E1 earthquake loading, while maintaining an overall elastic state. Under E2 and rare earthquake loading, the main plastic deformation is concentrated at the bent steel plate assembly 4. Because the initial stiffness of the weakened tie beam 3 and the bent steel plate assembly 4 is relatively low, the plastic hinge generated in the core area of ​​the pier-tie beam node under earthquake loading is transferred to the node area with the energy-dissipating devices, thus achieving the transfer and control of the plastic hinge. Simultaneously, the bent steel plate assemblies 4 are connected to the pier 1 and tie beam 2 via bolts, allowing for rapid replacement in the event of plastic deformation or even failure, demonstrating good replaceability and effectively enabling rapid restoration of traffic flow after earthquakes.

[0041] Example 2

[0042] like Figure 7 As shown, this embodiment provides another structure for a pressure-bearing bent steel plate assembly 4. Its installation position and method are the same as in Embodiment 1. It is located at the intersection of the pier 1 and the tie beam 2 and bolted to a pre-embedded high-strength threaded rod. Unlike Embodiment 1, the pressure-bearing bent steel plate assembly 4 in this embodiment includes a second bent steel plate 9, an L-shaped pressure-bearing steel plate 7, and pressure-bearing flanges 10. The two ends of the bent second steel plate 9 are welded between the inward-facing ends of the two L-shaped pressure-bearing steel plates 7. Four pressure-bearing flanges 10 are respectively welded to both sides of the L-shaped pressure-bearing steel plates 7 facing the center, with the second bent steel plate 9 located in the middle of the two pressure-bearing flanges 10. The pressure-bearing flanges 10 all extend horizontally inward but do not contact each other, maintaining a certain distance between them. Similar to Embodiment 1, the L-shaped pressure-bearing steel plate 7 in this embodiment has a significantly increased cross-sectional width compared to the second bent steel plate 9, facilitating connection with the pier 1 and the tie beam 2. Meanwhile, pressure flanges 10 are welded to both sides of the L-shaped pressure steel plate 7. The three-layer cover plate assembly 5 achieves the collision and compression of the pressure flanges 10 on both sides of the second bent steel plate 9 by restricting the vertical displacement of the L-shaped pressure steel plate 7 and the pressure flanges 10, thereby providing compressive bearing capacity, which corresponds to the tensile bearing capacity of the second bent steel plate 9, thereby reducing the adverse effects of weakening the tie beam 3.

[0043] The main difference between Example 1 and Example 2 lies in the bending steel plate assembly 4. The advantage of Example 1 is that the L-shaped pressure steel plate 7 in its bending steel plate assembly 4 has a larger collision and compression area than that of Example 2, which can provide greater compressive bearing capacity. The advantage of Example 2 is that its bending steel plate assembly 4 has only one layer of steel plate, which is simpler than the two-layer structure of the bending steel plate assembly 4 in Example 1. At the same time, it also makes the construction of the cover plate assembly 5 of Example 2 simpler.

[0044] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A bridge bent pier-tie beam joint with compressible folded steel plate, which is arranged at the intersection of a pier column (1) and a tie beam (2), characterized in that: The weakened tie beam (3) is located at the connecting end of the tie beam (2) towards the pier (1), and the cross-sectional height of the weakened tie beam (3) is smaller than that of the tie beam (2); the buckling steel plate assembly (4) of the compressible type is located on the upper and lower sides of the weakened tie beam (3), and the cover plate assembly (5) is fixedly clamped on the buckling steel plate assembly (4) on the upper and lower sides respectively; the two ends of the buckling steel plate assembly (4) on the upper and lower sides are fixedly connected with the pier (1) and the tie beam (2) respectively; The buckling steel plate assembly (4) includes a buckling steel plate and two L-shaped compression steel plates (7), the buckling steel plate has a elastic buckling part, and the two ends of the buckling part are fixedly connected with the two L-shaped compression steel plates (7) in the horizontal direction; the two L-shaped compression steel plates (7) are fixedly connected with the pier (1) and the tie beam (2) respectively; the cover plate assembly (5) includes an upper cover plate and a lower cover plate clamping an intermediate cover plate, the intermediate cover plate is located on the two sides of the L-shaped compression steel plate (7) and has two parts in the front-back direction, and the two sides of the upper and lower cover plates clamp the intermediate cover plate and are provided with bolt holes.

2. The bridge bent-pier-to-tie beam joint with compressible-type bent-up steel plates according to claim 1, characterized in that: The buckling steel plate is a first buckling steel plate (6), the first buckling steel plate (6) includes a buckling part protruding outward and extension parts at the two ends of the buckling part, and the extension parts are fixedly connected with the two L-shaped compression steel plates (7) in the horizontal direction towards the weakened tie beam (3).

3. The bridge bent-pier-to-tie beam joint with compressible-type bent-up steel plates according to claim 1, characterized in that: The buckling steel plate is a second buckling steel plate (9), the second buckling steel plate (9) includes a buckling part protruding outward, and the two ends of the buckling part are fixedly connected with the two L-shaped compression steel plates (7) in the inward direction; the second buckling steel plate (9) is provided with compression wing plates (10) on the two sides, the compression wing plates (10) are fixedly connected with the two L-shaped compression steel plates (7) in the inward direction on the two sides, extend in the horizontal direction towards the inside and are spaced apart by a certain distance.

4. The bridge bent-pier-to-tie beam joint with compressible-type folded steel plate of claim 2, wherein: The cross-sectional width of the L-shaped compression steel plate (7) is greater than that of the first buckling steel plate (6).

5. The bridge bent-pier-to-tie beam joint with compressible-type folded steel plate of claim 1, wherein: The shape of the buckling part is triangular or arc-shaped.

6. The bridge bent-pier-to-tie beam joint with compressible-type folded steel plates according to claim 5, characterized in that: The buckling part is provided with a chamfer at the buckling position.

7. The bridge bent-pier-to-tie beam node of claim 1, wherein: The pier (1) and the tie beam (2) are connected with the L-shaped compression steel plate (7) through a pre-embedded high-strength threaded rod.

8. The bridge bent-pier-to-tie beam node of claim 1, wherein: The longitudinal reinforcement in the weakened tie beam (3) is bent upwards and downwards respectively to form a diagonal steel bar (8).

9. The bridge bent-pier-to-tie-beam node of claim 8, wherein: The weakened tie beam (3) is provided with densified stirrups.

Images