Gravity type bridge combined anti-seismic block and design method

Abstract

The present application relates to a kind of gravity type bridge combination anti-seismic block and design method, including cap beam and the box girder erected on the upper end of cap beam, the bottom of box girder both sides is fixed with the steel slider of bottom arc, the slope section block is arranged in the both sides of cap beam, and the sliding slope section of steel slider is all arc surface shape from inside to outside in slope section block;Two upper bearing cushion stones are fixedly arranged on the interval of box girder lower end surface, two lower bearing cushion stones are fixedly arranged on the upper end surface of cap beam, two lower auxiliary blocks are fixedly arranged on the upper end surface of cap beam between two lower bearing cushion stones, and the upper auxiliary block is fixedly connected to two lower auxiliary blocks by high-strength shear bolt on the upper end of two lower auxiliary blocks, the rigid collision between traditional block and main beam is converted into the flexible sliding of material between slider and slope section, and the kinetic energy of earthquake is fully converted into the work of lifting main beam gravity and the friction between materials to realize energy dissipation and shock absorption effect, can realize multiple anti-seismic defense lines, significantly improve the seismic capacity and recovery capacity of bridge under the premise of protecting bridge structure component.

Description

TECHNICAL FIELD

[0001] The present application relates to a gravity type bridge combined anti-seismic block and design method. BACKGROUND

[0002] With the development of bridge construction, new technologies and new processes for bridge construction are constantly introduced, improved, created and developed, and the number of newly built bridges is increasing. For bridges in strong earthquake areas, especially for bridges crossing faults, large displacement will occur between the pier and the beam under the action of an earthquake. In order to prevent the occurrence of transverse beam falling, anti-seismic blocks are usually arranged at both ends of the pier and the bent cap.

[0003] Although the traditional anti-seismic block can reduce the probability of transverse beam falling, improper arrangement of the anti-seismic block can cause many serious problems. For example, if the rigidity of the block is too small, it will be easily damaged under the action of an earthquake, causing large displacement of the beam body and transverse beam falling, which brings great inconvenience to post-earthquake maintenance and reinforcement. If the rigidity of the block is too large, the collision between the block and the main beam will not only cause damage to the main beam itself, but also greatly increase the internal force of the substructure.

[0004] Among the existing technologies disclosed in the prior art, CN210797240U discloses a rolling and lifting type bridge anti-seismic block device, as shown in Figure 8 The main beam is arranged on the bent cap through a swing support, the two ends of the bent cap are provided with welded steel boxes, the side of the welded steel box facing the main beam is a stepped transition section with an arc shape, a rotating shaft is arranged perpendicularly to the steel rod, and a roller is arranged on the rotating shaft and abuts against the stepped surface of the lowermost step of the welded steel box. Under the action of an earthquake, the friction between the components and the work done by lifting the main beam against gravity are used to dissipate seismic energy, effectively achieving multi-channel defense against the action of an earthquake. Under the action of a small or medium earthquake, the friction between the rubber layer on the circular steel pie and the arc transition section of the welded steel box and the work done by lifting the main beam against gravity are used to dissipate seismic energy. Under the action of a strong earthquake, the friction between the rubber layer on the circular steel pie and the arc transition section of the welded steel box and the work done by lifting the main beam against gravity are used to dissipate seismic energy. However, the above-mentioned technology has the following disadvantages: 1. In the design process of the lifting type bridge anti-seismic block, how the beam body realizes vertical displacement during the sliding process of the circular steel pie is not considered. Disadvantage 2: The above-mentioned lifting type bridge anti-seismic block does not consider that the beam body will cause damage to the support after tilting during the sliding process. Disadvantage 3: The above-mentioned technology will cause the problem of disengagement of one end of the support during the sliding process of the beam body. Disadvantage 4: The anti-seismic block in the above-mentioned technology cannot realize self-resetting of the bridge beam body after an earthquake.

[0005] There are still some problems in the existing invention device using gravity type stop block. For example, in CN 213951911 U, only the upper sliding process of one side of the bridge beam body is considered, and how the other side of the bridge beam body moves in the lateral direction under the action of the earthquake is not carefully considered, that is, how the whole beam body realizes movement energy dissipation is not considered. Although the upper main beam has a sliding device on both sides in the above invention, the lateral and vertical movement of the main beam on the swing support is not considered, and the problem of damaging the support and causing the support to be empty during the movement of the main beam. SUMMARY

[0006] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to solve the problem that the conventional stop block is damaged and the main beam is locally damaged when it collides with the main beam under the action of lateral impact force of the earthquake due to its large stiffness, and even the lower structure is damaged. When the stop block is damaged, it is difficult to provide sufficient restoring force, which can cause large residual deformation of the main beam, increase the difficulty of bridge repair, and even cause the serious problem of beam falling.

[0007] In order to solve the above technical problems, the technical scheme of the present application is: a gravity type bridge combined anti-seismic stop block, comprising a bent cap and a box girder erected on the upper end of the bent cap, the bottom of the box girder on both sides is fixedly provided with a steel sliding block with a circular arc-shaped bottom, and the bent cap is symmetrically provided with a slope segment stop block on both sides for sliding of the two steel sliding blocks respectively, and the sliding slope segments of the slope segment stop block and the steel sliding block are all arc-shaped from inside to outside.

[0008] Further, the upper support pad, the lower support pad, the upper auxiliary stop block and the lower auxiliary stop block are transversely spaced, and a pot type rubber support is provided between the upper support pad and the lower support pad, and the lower end of the pot type rubber support is fixedly connected to the lower support pad.

[0009] Further, the upper auxiliary stop block has the same thickness as the upper support pad, and the lower auxiliary stop block has the same thickness as the lower support pad and the pot type rubber support.

[0010] Further, a plurality of rubber sliding blocks are further provided between the box girder and the bent cap, the rubber sliding blocks are arranged in a rectangular array, four rubber sliding blocks are arranged on the bent cap and are arranged in a staggered manner with the lower support pad and the lower auxiliary stop block, and the rubber sliding blocks are fixedly connected to the bent cap.

[0011] Further, the top of the slope section block is provided with a transverse block, and the inner side of the transverse block is a slope upwardly towards the box girder to abut the side end of the steel sliding block after sliding.

[0012] Further, the upper end surface of the slope section block is composed of a sliding slope section and a flat surface fixed with the transverse block, the bottom end of the sliding slope section is horizontal with the bottom end of the steel sliding block to facilitate butt joint, and a layer of polyethylene gasket is covered on the sliding slope section, and a layer of rubber gasket is covered on the arc surface of the lower end of the steel sliding block.

[0013] Further, the lower auxiliary block is fixed with the bent cap through the embedded steel bars in the bent cap, and a plurality of vertically extending and elongatable prestressed tendons are connected between the lower auxiliary block and the upper auxiliary block.

[0014] Further, the lower end of the bent cap is supported and fixed by the column pier.

[0015] A design method of a gravity type bridge combined anti-seismic block is performed according to the following steps: wherein the original parameters include: site category, earthquake frequency, earthquake grouping, earthquake intensity, damping ratio, response spectrum category, upper box girder mass m, bridge viscous damping coefficient c, bridge lateral stiffness k, peak ground acceleration a max , initial velocity v0 of the box girder under the action of the earthquake, surface friction coefficient μ1 of the polyethylene gasket, surface friction coefficient μ2 of the rubber sliding block, and friction coefficient μ3 of the rubber gasket on the lower surface of the steel sliding block.

[0016] The designable parameters include: sliding slope section 7 angle θ1 and steel sliding block 4 width L3.

[0017] The parameters to be designed include: sliding slope section radius R, sliding slope section projection length L1, and sliding slope section upper and lower height difference h. Step S1: determining the designable parameters of the bridge anti-seismic block structure and the friction coefficients of each sliding part; step S1.1: selecting the sliding slope section angle θ1 (30°-50°) and the width L3 (500-800 mm) of the steel sliding block according to the specific site working condition and the bridge; step S1.2: determining the surface friction coefficient μ1 of the polyethylene gasket, the surface friction coefficient μ2 of the rubber sliding block, and the friction coefficient μ3 of the rubber gasket 14 on the lower surface of the steel sliding block;

[0018] Step S2: calculating the initial velocity v0 of the box girder under the action of the earthquake;

[0019] Step S2.1: determining the site category, earthquake frequency, earthquake grouping, earthquake intensity, damping ratio, and response spectrum category parameters of the bridge located area according to the specification;

[0020] Step S2.2: determining the earthquake response spectrum from the original parameters in the above step S2.1;

[0021] Step S2.3: Obtain the acceleration time history from the seismic response spectrum in step S2.2, and determine the peak ground acceleration;

[0022] Step S2.4: Calculate the initial velocity v0 of the box girder under the action of earthquake;

[0023] v0=c1r1+c2r2 (Formula 1)

[0024] In the formula: r1—eigenvalue 1, c1—constant 1, r2—eigenvalue 2, c2—constant 2, m—mass of the box girder

[0025] c—viscous damping coefficient of the bridge

[0026] k—lateral stiffness of the bridge

[0027] a max —peak ground acceleration.

[0028] Step S3: Design the distances L1, L2, L4 between each component of the lower part of the box girder;

[0029] The projection length L1 of the sliding slope section is equal to the distance L2 from the steel slider to the distal edge of the auxiliary stop block on the side, and the distance L4 between the edge of the lower bearing padstone and the auxiliary stop block on the side is equal to the distance (width of the steel slider) from the tangent point of the bottom of the steel slider to the stop block of the slope section on the side. As shown in Formulas 2 and 3

[0030] L1=L2 (Formula 2)

[0031] L4=L3 (Formula 3)

[0032] Step S4: Calculate the radius R of the sliding slope section;

[0033]

[0034] In the formula: v0—initial velocity of the box girder under the action of earthquake

[0035] g—acceleration of gravity

[0036] θ1—angle of the sliding slope section

[0037] μ1—surface friction coefficient of the polyethylene gasket

[0038] μ2—surface friction coefficient of the rubber slider

[0039] μ3—friction coefficient of the rubber gasket on the lower surface of the steel slider

[0040] μ 2，3 —μ 2，3 =μ2+μ3

[0041] μ 1，3 —μ 1，3 = μ1+ μ3

[0042] α—α= a c rtan(μ 1,3 )

[0043]

[0044] Step S5: calculate the projection length L1 of the sliding slope section;

[0045]

[0046] In the formula, the other parameters are defined in the same way as in formula 4.

[0047] Step S6: calculate the height difference h of the sliding slope section

[0048]

[0049] In the formula, the other parameters are defined in the same way as in formula 4.

[0050] Compared with the prior art, the present application has the following beneficial effects: the present application can convert the direct rigid collision between the bridge block and the beam body into flexible sliding of the steel sliding block and the slope block, directly protecting the safety of the beam body and the block structure. At the same time, by overcoming the gravity of the beam body and overcoming the high frictional force between the lower steel sliding block of the beam body and the slope block, the transverse kinetic energy input by the earthquake to the bridge is fully and effectively dissipated. Also, by designing rubber sliding blocks between the box girder and the bent cap, and by coordinating the upper and lower auxiliary blocks and the circular arc section, the beam body can be fully moved in the transverse and vertical directions under the premise of protecting the bridge support, and more seismic kinetic energy is consumed. Specifically:

[0051] 1: The device can realize the vertical displacement of the beam body and realize the gravity energy dissipation of the beam body. 2: The device can ensure the safety of the support structure when the bridge occurs vertical displacement. 3: The device can realize the self-resetting function of the bridge beam body after the earthquake. Advantage 4: The device can avoid the direct rigid collision between the beam body and the block, which can protect the safety of the block and the bridge component.

[0052] The present application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is a schematic view of the structure of the embodiment of the present application;

[0054] Figure 2 is a top view of the embodiment of the present application without the box girder;

[0055] Figure 3Connection diagram of upper auxiliary stopper and lower auxiliary stopper in the embodiment of the present application;

[0056] Figure 4 Force analysis diagram of the box girder sliding in the embodiment of the present application;

[0057] Figure 5 Design flow chart of the embodiment of the present application;

[0058] Figure 6 Working diagram of the embodiment of the present application when subjected to the frequently-encountered earthquake;

[0059] Figure 7 Working diagram of the embodiment of the present application when subjected to the rarely-encountered earthquake;

[0060] Figure 8 Structure diagram of a rolling and lifting type bridge anti-seismic stopper device.

[0061] In the figure: 1-box girder, 2-cap beam, 3-column pier, 4-steel sliding block, 5-polyethylene gasket, 6-transverse stopper, 7-slope section stopper, 8-upper support cushion stone, 9-basin type rubber support, 10-lower support cushion stone, 11-upper auxiliary stopper, 12-lower auxiliary stopper, 13-rubber sliding block, 14-rubber gasket, 15-sliding slope section, 16-flattened surface, 101-high-strength shear bolt, 102-prestressed tendon, 103-embedded steel bar. DETAILED DESCRIPTION

[0062] In order to make the above features and advantages of the present application more obvious and easy to understand, the following embodiments are specifically described, and the detailed description is as follows in combination with the drawings.

[0063] As Figures 1-7 shown, a gravity type bridge combined anti-seismic stopper includes the following states in working:

[0064] I. Normal use state

[0065] As Figure 1 shown, when in the normal use state, the bridge stably falls on the support and the rubber sliding block due to the self weight of the box girder, and does not move and deviate laterally.

[0066] II. When subjected to the frequently-encountered earthquake

[0067] As Figure 6As shown, when the bridge is subjected to a common earthquake, the superstructure box girder 1 will move laterally under the action of the seismic lateral force. Since the steel upper support pad 8 is fixed to the lower part of the box girder, the lateral movement of the box girder will drive the steel upper support pad 8 to move. After the lateral displacement occurs, the upper support pad 8 will come into contact with and collide with the upper auxiliary stop 11. The upper auxiliary stop 11 is connected to the lower auxiliary stop 12 by shear pins 101 and elongated tensile prestressed steel bars. The shear resistance of the pins and the tensile resistance of the steel bars dissipate the lateral kinetic energy of the earthquake. The steel slider 4 eventually contacts but does not impact the sliding slope section 5 of the slope stop 7. In this process, the anti-fall function of the stop is mainly achieved through the frictional energy dissipation of the relative motion between the box girder itself and the rubber slider material, and the restriction of the box girder movement by the auxiliary stop.

[0068] III. When a rare earthquake occurs

[0069] like Figure 7 As shown, when the bridge is subjected to a rare earthquake, the shear bolts 101 and the elongated tensile prestressed tendons 102 installed between the upper auxiliary block 11 and the lower auxiliary block 12 will be sheared and pulled out respectively under the collision of the upper box girder 1 and the upper support pad 8. Therefore, the upper main girder will break through the restriction of the upper auxiliary block and slide freely up the slope blocks on both sides. During the sliding process, on the one hand, the box girder itself will generate sliding friction with the rubber slider 13 installed at the bottom; on the other hand, the rubber pad installed at the bottom of the steel slider 4 will fully contact and rub against the polyethylene material pad 5 on the surface of the sliding slope section 7, and fully dissipate the energy input by the earthquake during the friction process. When the upper box girder 1 overcomes its own weight and reaches the highest point of the sliding slope section, it will come into contact with and collide with the transverse block 6 made of high-toughness concrete installed at the top of the slope. At this time, the input seismic energy will be fully dissipated by a series of energy dissipation means, including the energy dissipation from the collision of the upper support pad, the energy dissipation from friction during the sliding process, the energy dissipation from the work done to overcome gravity, and the energy dissipation from the collision of the transverse block.

[0070] The upper box girder, after energy dissipation, will slowly slide down the slope along the retaining blocks under its own weight. During this process, it will again dissipate energy through friction. Finally, the girder will stop moving under the resistance of the upper auxiliary block 8, achieving partial self-resetting. The upper girder can be reset by simply adjusting its position. The upper auxiliary block 8, which has been damaged by the collision, can be recast and replaced. The rubber gaskets and polyethylene pads of the compressed and deformed sliders can also be repaired or replaced as needed, achieving rapid restoration of the bridge's function.

[0071] The embodiments of the present invention have the following advantages:

[0072] Advantage 1: This device can realize the vertical displacement of the beam and realize the energy dissipation of the beam's weight.

[0073] The device is free from the problem that the beam body directly slides on the support, can make the upper box girder freely slide along the sliding slope section, can slide on the rubber sliding block at one end, and easily realizes vertical displacement without causing the problem that the beam body is separated from the support.

[0074] Advantage 2: The device can ensure the safety of the support structure when the bridge vertically displaces.

[0075] The device directly provides four rubber sliding blocks for the upper box girder and the lower cover beam to slide horizontally and vertically, and the height of the sliding block just fills the gap between the upper and lower beam bodies, so that the support is contacted but not extruded when the box girder drives the upper support cushion stone to slide, thereby ensuring the safety and durability of the support structure.

[0076] Advantage 3: The device can realize the self-resetting function of the bridge beam after an earthquake.

[0077] When the box girder slides to the highest point of the slope under a rare earthquake, the circular arc-shaped steel sliding block collides with the high-toughness concrete transverse block arranged at the highest point, and since most of the earthquake energy is dissipated at this time, the box girder completely loses the horizontal kinetic energy after the collision and slides down along the circular arc section under the action of gravity. Due to the design of the upper and lower auxiliary blocks, the horizontal movement of the steel support cushion stone on one side is blocked, so that the horizontal movement of the box girder is terminated. After the final stop, the box girder on the upper part of the arc-shaped slope block will automatically slide down and reset due to gravity.

[0078] Advantage 4: The device can avoid the rigid collision between the beam body and the block, and can protect the safety of the block and the bridge component.

[0079] The bottom of the box girder lower steel sliding block is provided with a layer of rubber gasket, and the circular arc slope of the block is provided with a layer of polyethylene pad. Both materials have high wear resistance and slip resistance, and can be extruded and deformed when they contact, thereby relieving the horizontal kinetic energy of the beam body. And since the curvature of the sliding block is the same as that of the slope, the sliding of the beam body can be better realized.

[0080] The present application is not limited to the above-mentioned best embodiment, and anyone can derive other various forms of gravity type bridge combined anti-seismic block and design method under the inspiration of the present application. Any equivalent changes and modifications made within the scope of the present application shall be covered by the present application.

Claims

1. A gravity type bridge combined seismic fender, characterized in that: The utility model relates to a kind of gravity type bridge combined anti-seismic block, including bent cap and box girder erected on the upper end of bent cap, the bottom of box girder is solidly equipped with steel slider with bottom arc, the bent cap both sides are symmetrically provided with the slope segment stopper for two steel sliders sliding respectively, the slope segment stopper and the sliding slope segment of steel slider are all inclined upward arc surface from inside to outside;Two upper bearing padstones are spaced and fixed on the lower end surface of box girder, two lower bearing padstones are fixed on the upper end surface of bent cap and are one-to-one corresponding with upper bearing padstone and sliding connection, two lower auxiliary stoppers are spaced and fixed on the upper end surface of bent cap between two lower bearing padstones, and upper auxiliary stopper is fixed on the upper end of two lower auxiliary stoppers by high-strength shear bolt; The upper bearing padstone, lower bearing padstone, upper auxiliary stopper and lower auxiliary stopper are horizontally spaced, and the upper bearing padstone and lower bearing padstone are padded with a pot rubber bearing, and the lower end of the pot rubber bearing is fixed on the lower bearing padstone; The upper auxiliary stopper has the same thickness as the upper bearing padstone, and the lower auxiliary stopper has the same thickness as the lower bearing padstone and the pot rubber bearing; The box girder and the bent cap are further padded with a plurality of rubber sliders, which are arranged in a rectangular array on the bent cap and are arranged in a staggered manner with the lower bearing padstone and the lower auxiliary stopper, and the rubber sliders are fixed on the bent cap; The top of the slope segment stopper is fixed with a horizontal stopper, and the inner side of the horizontal stopper is inclined upward to the box girder to abut against the side end of the steel slider after sliding; The upper end surface of the slope segment stopper is composed of a sliding slope segment and a flat surface fixed with the horizontal stopper, the bottom end of the sliding slope segment is horizontal with the bottom end of the steel slider to facilitate docking, a layer of polyethylene gasket is covered on the sliding slope segment, and a layer of rubber gasket is covered on the lower end arc surface of the steel slider; The lower auxiliary stopper is fixed on the bent cap by the embedded steel bar in the bent cap, and a plurality of prestressed tendons are connected between the lower auxiliary stopper and the upper auxiliary stopper.

2. The gravity type bridge combined anti-seismic block according to claim 1, characterized in that: The lower end of the bent cap is supported and fixed by a column pier.

3. A design method of gravity type bridge combined seismic fender block, characterized in that, The gravity type bridge combined anti-seismic block according to any one of claims 1-2 is used, and the following steps are performed: Step S1: determine the design parameters of the bridge combined anti-seismic block and the friction coefficients of each sliding part; Step S1.1: according to the specific site conditions and the bridge, the angle θ1 of the slope segment stopper sliding slope segment is selected, θ1 is 30°-50°, and the width L3 of the steel slider is selected, L3 is 500-800 mm; Step S1.2: determine the surface friction coefficient μ1 of the polyethylene gasket, the surface friction coefficient μ2 of the rubber slider, and the friction coefficient μ3 of the rubber gasket on the lower surface of the steel slider; Step S2: calculate the initial velocity v0 of the box girder under the action of earthquake; Step S3: design the distance L1, L2, L4 between each component of the lower part of the box girder; The projected length L1 of the sliding slope segment is equal to the distance L2 from the steel slider to the far end edge of the upper auxiliary stopper on the same side, and the distance L4 between the edge of the lower bearing padstone and the lower auxiliary stopper on the same side is equal to the width L3 of the steel slider; as shown in formulas 2 and 3 L1=L2 (Formula 2) L4=L3 (Formula 3) Step S4: calculate the radius R of the sliding slope segment; In the formula: v0 is the initial velocity of the box girder under the action of earthquake g is the acceleration of gravity θ1 is the angle of the sliding slope segment μ1 is the surface friction coefficient of the polyethylene gasket μ2—surface friction coefficient of rubber slide block μ3—friction coefficient of rubber gasket under the lower surface of steel slide block μ 2，3 —μ 2，3 = μ2+ μ3 μ 1，3 —μ 1，3 = μ1+ μ3 a-a = arctan (μ 1,3 ) Step S5: Calculate the projection length L1 of the sliding slope section; v0—initial velocity of box girder under earthquake action g—gravity acceleration θ1—angle of sliding slope section μ1—surface friction coefficient of polyethylene gasket μ2—surface friction coefficient of rubber slide block μ3—friction coefficient of rubber gasket under the lower surface of steel slide block μ 2，3 —μ 2，3 = μ2+ μ3 μ 1，3 —μ 1，3 = μ1+ μ3 a-a = arctan (μ 1,3 ) Step S6: Calculate the height difference h of the sliding slope section v0—initial velocity of box girder under earthquake action g—gravity acceleration θ1—angle of sliding slope section μ1—surface friction coefficient of polyethylene gasket μ2—surface friction coefficient of rubber slide block μ3—friction coefficient of rubber gasket under the lower surface of steel slide block μ 2，3 —μ 2，3 = μ2+ μ3 μ 1，3 —μ 1，3 = μ1+ μ3 a-a = arctan (μ 1,3 ) 4. The design method of a gravity type bridge combined anti-seismic block according to claim 3, characterized in that: Step S2.1: Determine the site category, earthquake frequency, earthquake grouping, earthquake intensity, damping ratio, and response spectrum category parameters of the bridge according to the specifications; Step S2.2: Determine the seismic response spectrum from the original parameters in step S2.1; Step S2.3: Obtain the acceleration time history from the seismic response spectrum in step S2.2, and determine the peak ground acceleration; Step S2.4: Calculate the initial velocity v0 of the box girder under earthquake action.

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