Anti-falling beam device of bridge in earthquake area and design method thereof

Abstract

The application discloses a kind of anti-falling beam device of earthquake area bridge and its design method, and the anti-falling beam device includes steel sleeve, the steel sleeve is located at least one side of beam body, the steel sleeve and the abutment cushion stone of corresponding side have interval, the steel sleeve and beam body are connected by connecting piece, the connecting piece includes first connecting end, second connecting end and the rod body between them, the first connecting end is connected in the steel sleeve, and the second connecting end connects the beam body;The cross-sectional dimension of the first connecting end and the second connecting end is all greater than the cross-sectional dimension of the rod body, and / or, the elastic modulus of the first connecting end and the second connecting end is all greater than the elastic modulus of the rod body.This device under the action of earthquake, small section or small elastic modulus part first plastic deformation is carried out to dissipate energy, to reduce the influence of seismic force on bridge structure, to local plastic deformation to achieve energy dissipation effect, reduce the damage of earthquake to bridge, facilitate post-earthquake repair.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge, in particular to a bridge beam falling prevention device for earthquake area and a design method thereof. BACKGROUND

[0002] Under the action of strong earthquake, a large relative displacement is easily generated between the upper and lower structures of a bridge, and when the displacement exceeds the actual length of the bridge or the limit of the beam falling prevention device, beam falling earthquake disaster occurs, which is difficult to repair, and the bridge as the throat of land traffic will directly cut off the traffic route after being damaged, seriously hinder the emergency rescue in the disaster area, the post-disaster reconstruction and the reduction of the overall social function, and has a huge impact and the indirect loss caused is difficult to estimate.

[0003] The traditional beam falling prevention device for railway bridge is pre-buried with a steel plate at the bottom of the beam and a profile steel block is installed, when the seismic intensity exceeds the designed seismic intensity, the bearing bolt is sheared, the beam body and the pier body have a horizontal relative displacement, the profile steel block contacts the supporting cushion stone, and the displacement of the beam body is limited and the beam body is prevented from falling. However, the traditional profile steel block for beam falling prevention has the following defects: 1) the profile steel block is a rigid component, and the collision effect and damage thereof are difficult to estimate; 2) the stress deformation of the profile steel block during the earthquake cannot be accurately calculated; 3) only one side of the profile steel block plays a role when the beam body is displaced; 4) the profile steel block is an anisotropic component, and there is an obvious weak axis direction; 5) the profile steel block relies on the supporting cushion stone for limiting, and in order to meet the structural and stress requirements, the size of the supporting cushion stone needs to be increased, which further leads to the increase in the size of the pier top cap and the pier body structure; 6) the supporting cushion stone is easily damaged due to collision during the earthquake, and it is difficult to repair, and it causes safety hazards to the bearing and the beam body located on the supporting cushion stone; and 7) the profile steel block for beam falling prevention is located at the bottom of the beam, and it is inconvenient for daily inspection and maintenance and post-earthquake repair. SUMMARY

[0004] The present application aims to overcome the above-mentioned deficiencies in the prior art that the beam falling prevention block is inconvenient to install, difficult to maintain and repair after the earthquake, and provides a beam falling prevention device for bridge in earthquake area and a design method thereof.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The application discloses a falling beam prevention device for a bridge in a seismic area, which comprises a steel sleeve, the steel sleeve is arranged on at least one side of a beam body, the steel sleeve has a spacing with a support cushion stone on the corresponding side, a connecting piece is arranged between the steel sleeve and the beam body, the connecting piece comprises a first connecting end, a second connecting end and a rod body between the first connecting end and the second connecting end, the first connecting end is connected in the steel sleeve, and the second connecting end is connected with the beam body; the cross-sectional size of the first connecting end and the second connecting end is greater than the cross-sectional size of the rod body, and / or the elastic modulus of the first connecting end and the second connecting end is greater than the elastic modulus of the rod body.

[0007] The cross-sectional size of the first connecting end and the second connecting end is greater than the cross-sectional size of the rod body, which can be that the height of the two ends is greater than the height of the rod body, or the width of the two ends is greater than the width of the rod body, or the width and height of the two ends are greater than the width and height of the rod body, and the cross-sectional size of the first connecting end and the second connecting end is not limited to be consistent, and is determined according to the connecting performance of the corresponding end. The rod body can be an equal cross-section structure or a variable cross-section structure; when the rod body is arranged in an equal cross-section, that is, the stiffness is consistent, reliable rigid connection can be provided during an earthquake, and when damping and energy consumption are required, a variable cross-section form is preferably selected according to the seismic resistance requirement of the bridge site.

[0008] The falling beam prevention device for the bridge in the seismic area is arranged on at least one side of the beam body, that is, the steel sleeve is arranged on the outer side of the beam body, compared with the support cushion stone arranged at the bottom of the beam body and used for preventing the falling of the beam, the installation space is large, the installation is convenient, and the maintenance is convenient; the steel sleeve and the support cushion stone have a reserved space therebetween, so that the cushion stone is not affected after the device is deformed, and the support cushion stone does not need to be used for preventing the falling of the beam as in the prior art, the maintenance of the support cushion stone is avoided, and the safety hidden danger of the support and the beam body on the support cushion stone is prevented; the connecting piece is arranged between the steel sleeve and the beam body to prevent the falling of the beam, meanwhile, the isotropic characteristics of the sleeve pipe can be utilized to realize the limiting effect of the same device in the longitudinal and transverse directions, there is no obvious weak axis direction, and the size does not need to be significantly increased to meet the structure and stress requirements, so that the size of the pier top cap and the pier body structure is not increased, and cost is saved; the cross-sectional size and / or the elastic modulus of the first connecting end and the second connecting end of the connecting piece are greater than the cross-sectional size and / or the elastic modulus of the rod body, under the action of an earthquake, the parts with small cross sections or small elastic modulus are firstly deformed plastically to consume energy, so as to reduce the influence of the earthquake force on the bridge structure; or the rod body is connected by different materials, the materials at the two ends have large elastic modulus, and the material in the middle has small elastic modulus, which is also deformed plastically to consume energy under the earthquake, so that the local plastic deformation can achieve the energy consumption effect, the damage of the earthquake to the bridge is reduced, and the post-earthquake repair is facilitated.

[0009] Preferably, the first connecting end and the steel sleeve have a movable gap in the longitudinal bridge direction and / or the transverse bridge direction.

[0010] Satisfy the normal working displacement requirement of the beam body.

[0011] Further preferably, the top end of the steel sleeve has an opening for placing the connecting member, and the first connecting end has a vertical clearance with the steel sleeve.

[0012] The anti-falling beam device is convenient to install, and the specific size of the opening can be set according to whether there is a vertical limiting requirement.

[0013] Further preferably, the width of the opening is p, tw <p< Ly , tw represents the thickness of the rod body, Ly represents the width of the first connecting end.

[0014] When vertical limiting is required, the above-mentioned size is adopted, which is convenient to place the steel sleeve through the rod body to adapt to the anti-falling beam requirements in high-intensity earthquake areas, such as 9-degree earthquake areas and near active fault areas.

[0015] Preferably, the steel sleeve is connected to the top cap steel bar, and the second connecting end is connected to the steel bar of the beam body through a U-shaped bolt.

[0016] Preferably, when the cross-sectional size of the first connecting end and the second connecting end is greater than the cross-sectional size of the rod body, the thickness of the first connecting end and the second connecting end is greater than the thickness of the rod body.

[0017] Adjusting the thickness has a better effect on adjusting the stiffness.

[0018] Preferably, a plurality of anti-falling beam devices are arranged along the longitudinal bridge direction, and the stiffness of at least two of the anti-falling beam devices is different.

[0019] The number and spacing of the anti-falling beam devices can be determined according to the influence of seismic motion on the bridge at the bridge site.

[0020] In areas with high seismic intensity and frequent earthquakes, or in the short term after a strong earthquake, when a large aftershock occurs and the bridge anti-falling beam device is damaged and cannot be replaced and restored in time, a plurality of anti-falling beam devices with different stiffnesses can be arranged to achieve the functions of damaging the device with smaller stiffness after the first earthquake, resisting aftershocks, and preventing beam falling, so as to reduce the impact of earthquakes and reduce losses.

[0021] A design method of an anti-falling beam device is applied to the anti-falling beam device of the bridge in any of the above-mentioned earthquake areas, and includes the following steps:

[0022] a. Determine the horizontal seismic force borne by the anti-falling beam device according to the preset seismic wave at the bridge site F he ; according to the distance between the steel sleeve and the edge of the support cushion stonedx determining the length of each connector L and the outer diameter D and inner diameter d of the steel sleeve, and according to the length of each connector (3) L determining the horizontal seismic force borne by the corresponding connector (3) F hei ;

[0023] b, according to Ly determining the width of the first connecting end Ly , a representing the longitudinal displacement requirement of the connector; according to F hei ( Ly -2×π×d1 2 / 4)× tg) determining the thickness of the second connecting end tg , [σ] representing the tensile allowable stress of the second connecting end, and d1 representing the diameter of the connecting part of the second connecting end and the beam body; determining the first thickness of the first connecting end t 1, and then according to hw=L - t 1- tg calculating the length of the beam body hw ;

[0024] c, according to tw ≥ hw / 160 determining the thickness of the beam body tw , according to b≥ F hei / ([σ]× tw ) determining the width b of the beam body

[0025] d, according to F hei / (2× t 2× tw )≤ determining the second thickness of the first connecting end t 2, representing the shear allowable stress of the first connecting end; if t 2≤ t 1, the thickness of the first connecting end is taken as t 1, and then according to (Ly-b) / 2 t 1≤13 checking the width of the first connecting end Ly , if Ly satisfies the requirement, the size determination of the connector is completed

[0026] e, according to W=π×(D 4 -d 4) / 32D, to determine whether the wall thickness (D-d) / 2 of the steel sleeve meets the stress requirement, wherein σ=M / W≤[σ], M is the bending moment of the steel sleeve under the most unfavorable working condition in the earthquake, M= F hei ×H; H is the distance from the center of the rod to the top of the pier, W is the sectional modulus of the steel sleeve, σ is the bending stress of the steel sleeve, [σ] is the allowable bending stress of the steel sleeve material; if D and d both meet the stress requirement, the size determination of the steel sleeve is completed; then according to checking the length of the connecting piece L whether it meets the requirement, wherein E g is the elastic modulus of the steel sleeve, I g is the sectional moment of inertia of the steel sleeve, Ig=π×D 4 ×(1-(d / D) 4 ) / 64, H is the distance from the center of the rod to the top of the pier, hd is the thickness of the bearing cushion stone; according to checking the horizontal seismic force borne by the corresponding connecting piece F hei whether it meets the requirement, wherein, , i m represents the area linear stiffness of the connecting piece, i mi represents the area linear stiffness of the first i connecting piece, E i represents the elastic modulus of the first i connecting piece, A i represents the sectional area of the first i connecting piece; if L and F hei both meet the requirement, the design of the anti-falling beam device is completed.

[0027] Preferably, if the top end of the steel sleeve has an opening, the width p of the opening is determined according to the width b or thickness tw of the rod.

[0028] Further preferably, if the bridge site is located in a 9-degree seismic fortification zone, in step a, it also contains determining the vertical seismic force borne by the anti-falling beam device F se and the vertical seismic force borne by the corresponding connecting piece F sei； In step e, the bending moment of the steel sleeve under the most unfavorable working condition in the earthquake is replaced by M= F hei ×H+ F sei ×D / 2, and the bending stress of the steel sleeve is replaced by σ=(M / W+F sei / A)≤[σ], and verify the shear resistance requirement. and F sei , F sei / ((b- tw )× tw )≤ Where A = π × D 2 ×(1-α 2 ) / 4, where A is the cross-sectional area of ​​the steel sleeve, and α = d / D; ,in, , i i The linear stiffness of the moment of inertia of the connecting component. i ii Indicates the first i Moment of inertia linear stiffness of each connector E i Indicates the first i The elastic modulus of each connector I i Indicates the first i The moment of inertia of the cross section of each connector.

[0029] The design method of the anti-fall beam device described in this invention allows for the use of connector groups with different lengths, cross-sectional areas, and material combinations as needed. This enables some connectors to yield and fail prematurely under seismic loads, achieving vibration reduction and energy dissipation, thus effectively realizing multi-level anti-fall beam protection for the bridge structure. The distribution of seismic forces is achieved by using the area stiffness ratio and moment of inertia stiffness ratio of each connector within the connector group, resulting in accurate stress calculation and dimensional optimization of each connector, maximizing the utilization of connector materials. This facilitates the use of a single device for anti-fall beam and vibration reduction / energy dissipation in the longitudinal, transverse, and vertical directions, effectively improving device utilization, saving space on pier tops, and significantly enhancing the adaptability of bridges in high-intensity earthquake zones.

[0030] In summary, compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. The anti-falling beam device for a bridge in a seismic area according to the application, the steel sleeve is located outside the beam body, compared with the support cushion stone for preventing beam falling arranged at the bottom of the beam body, the installation space is large, the installation is convenient, the maintenance is convenient, the space is reserved between the steel sleeve and the support cushion stone, so that the device has no influence on the cushion stone after deformation, and it is not necessary to use the cushion stone to prevent beam falling as in the prior art, the maintenance of the support cushion stone is avoided, and the safety hidden danger of the support and the beam body on the cushion stone is also prevented; the connecting piece is arranged between the steel sleeve and the beam body to prevent beam falling, meanwhile, the isotropic characteristics of the sleeve pipe are utilized, the same device can realize the limiting action in longitudinal and transverse directions, there is no obvious weak axis direction, and the size does not need to be significantly increased to meet the structure and stress requirements, so that the size of the pier top cap and the pier body structure is not increased, which is beneficial to save cost; the cross-sectional size and / or elastic modulus of the first connecting end and the second connecting end of the connecting piece are larger than the cross-sectional size or elastic modulus of the rod body, under the action of the earthquake, the parts with small cross section or small elastic modulus are firstly deformed plastically to dissipate energy, so as to reduce the influence of the earthquake force on the bridge structure; or the rod body is connected by different materials, the materials at the two ends have large elastic modulus, and the material in the middle has small elastic modulus, which also deforms plastically to dissipate energy under the earthquake, so that the local plastic deformation can achieve the energy dissipation effect, reduce the damage of the earthquake to the bridge, and facilitate the post-earthquake repair.

[0032] 2. The design method of the anti-falling beam device according to the application can adopt connecting piece groups with different lengths, different cross-sectional areas and different material combinations according to needs, so that part of the connecting pieces can be designed to yield and break first to achieve the effect of shock absorption and energy dissipation under the action of the earthquake, and the multi-stage anti-falling beam protection of the beam body is effectively realized. The area linear stiffness ratio and the inertia moment linear stiffness ratio of each connecting piece in the connecting piece group are used to distribute the earthquake force, so as to realize the precise force calculation and size optimization of each connecting piece, and the maximum utilization of the connecting piece material is better realized. It is convenient to use a set of devices for longitudinal, transverse and vertical anti-falling beam and shock absorption and energy dissipation, which effectively improves the utilization rate of the device, saves the space arranged on the pier top, and effectively improves the adaptability of the bridge in the high-intensity seismic area. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a layout cross-sectional view of the anti-falling beam device for a bridge in a seismic area according to the application.

[0034] Figure 2 It is a layout top view of the anti-falling beam device for a bridge in a seismic area according to the application.

[0035] Figure 3 It is a plane view of the connecting piece of embodiment 1 Figure 1 ;

[0036] Figure 4 It is a plane view of the connecting piece of embodiment 1Figure 2 ;

[0037] Figure 5 is a plan view of the connection relationship between the connecting piece and the steel sleeve of Example 1;

[0038] Figure 6 is a sectional view of A-A of Figure 5 ;

[0039] Figure 7 is a plan view of the connection relationship between the connecting piece and the steel sleeve of Example 2;

[0040] Figure 8 is a sectional view of B-B of Figure 7 ;

[0041] Figure 9 is a flow chart of a design method of a beam falling prevention device according to the present application.

[0042] Marked in the figure: 1-steel sleeve, 2-beam body, 3-connecting piece, 31-first connecting end, 32-second connecting end, 33-rod body, 4-support pad stone. DETAILED DESCRIPTION

[0043] The present application will be further described in conjunction with the accompanying drawings and specific examples. However, it should not be understood that the above-mentioned subject matter of the present application is limited to the following examples only, and any technology realized based on the content of the present application falls within the scope of the present application.

[0044] Example 1

[0045] As shown in Figures 1-2 , a beam falling prevention device for a bridge in a seismic area according to the present application comprises a steel sleeve 1, the steel sleeve 1 is located on at least one side of a beam body 2, the steel sleeve 1 has a spacing with a support pad stone 4 on the corresponding side, the steel sleeve 1 and the beam body 2 are connected through a connecting piece 3, the connecting piece 3 comprises a first connecting end 31, a second connecting end 32 and a rod body 33 between the two, the first connecting end 31 is connected in the steel sleeve 1, and the second connecting end 32 is connected to the beam body 2; the cross-sectional size of the first connecting end 31 and the second connecting end 32 is greater than the cross-sectional size of the rod body 33, and / or the elastic modulus of the first connecting end 31 and the second connecting end 32 is greater than the elastic modulus of the rod body 33.

[0046] Specifically, the cross-sectional size of the first connecting end 31 and the second connecting end 32 is larger than the cross-sectional size of the rod body 33, which can be that the height of the two ends is larger than the height of the rod body 33, or the width of the two ends is larger than the width of the rod body 33, or the width and height of the two ends are larger than the width and height of the rod body 33. From the cross-sectional characteristics, the effect of the thickness direction is better than that of the width direction, the rod body 33 can be equal cross-section, such as Figure 3 , that is, the rod body 33 has consistent rigidity, and more reliable rigid connection is provided during the earthquake. When there is a requirement for shock absorption and energy dissipation, a variable cross-section form is preferably selected, such as Figure 4 , according to the seismic requirements of the bridge site, the rigidity of the middle part is smaller and the rigidity of the two ends is larger, that is, a dumbbell structure, and the cross-sectional shape of the rod body 33 is not limited, which can be rectangular or I-shaped.

[0047] The steel sleeve 1 is arranged on at least one side of the beam body 2, that is, the steel sleeve 1 is located outside the beam body 2 and arranged along the longitudinal bridge direction. The steel sleeve 1 is connected to the top cap steel bar, and the second connecting end 32 is connected to the steel bar of the beam body 2 through a U-shaped bolt. Compared with the support cushion stone 4 arranged at the bottom of the beam body 2 and used for preventing beam falling, the installation space is large, the installation is convenient, and the maintenance is convenient. A space is reserved between the steel sleeve 1 and the support cushion stone 4, so that the device does not affect the cushion stone after deformation, and there is no need to use the cushion stone to prevent beam falling as in the prior art, thereby avoiding the maintenance of the support cushion stone 4 and preventing safety hazards to the support and the beam body located on the cushion stone. By arranging the connecting piece 3 between the steel sleeve 1 and the beam body 2, the beam body 2 is prevented from falling, and at the same time, the isotropic characteristics of the circular cross-section of the steel sleeve 1 can realize the limiting effect of the same device in the longitudinal and transverse directions. There is no obvious weak axis direction, and there is no need to significantly increase the size to meet the construction and stress requirements, thereby avoiding the increase of the size of the pier top cap and the pier body structure, which is beneficial to save cost. The cross-sectional size and / or elastic modulus of the first connecting end 31 and the second connecting end 32 of the connecting piece 3 are larger than the cross-sectional size or elastic modulus of the rod body 33. Under the action of the earthquake, the parts with small cross-section or small elastic modulus are first deformed plastically to dissipate energy, so as to reduce the influence of the earthquake force on the bridge structure. Or the rod body is connected by different materials, the materials at the two ends have large elastic modulus, and the material in the middle has small elastic modulus. During the earthquake, the materials are first deformed plastically to dissipate energy, so as to reduce the damage of the earthquake to the bridge and facilitate post-earthquake repair.

[0048] When arranged along the longitudinal bridge direction, the connecting piece 3 can be arranged in equal length as shown in the upper half of Figure 2 , or when the space of the equal length device arranged on the top of the pier is limited, the connecting piece 3 can be arranged in equal length as shown in the lower half of Figure 2The unequal length arrangement shown in the lower half, the connecting piece 3 is short, then the rigidity is large, and the seismic force borne under the action of the earthquake is relatively large. If the unequal length arrangement is adopted, that is, the rigidity of each anti-falling beam device is different, for example, the length of the connecting piece 3 near the support is of a smaller size. When an earthquake occurs, the device with a larger preset rigidity bears a larger seismic force and is damaged first through energy dissipation. That is, the devices can be damaged at different times when a certain earthquake occurs. When the aftershock occurs, the device with smaller rigidity is further acted upon. Moreover, when the length of the connecting piece 3 at the support is shorter, the steel sleeve 1 at this position is also closer to the beam body 2. When an earthquake occurs, the movement direction of the beam body 2 may not be perpendicular to the support. Even if the connecting piece 3 is completely damaged, when the beam body continues to move in the aftershock, the steel sleeve 1 closest to the beam body 2 can still be relied on to block and protect, preventing the beam from falling and further improving the effect of preventing the beam from falling.

[0049] The first connecting end 31 and the steel sleeve 1 have a movable gap in the longitudinal bridge direction and / or the transverse bridge direction, as shown in Figure 5 , to facilitate the normal working displacement requirement of the beam body 2. A small hole can be formed in the steel sleeve 1 at the pier top position to facilitate the entry of rainwater into the sleeve during the later use process and the discharge of the rainwater. The top end of the steel sleeve 1 has an opening for placing the connecting piece 3. The first connecting end 31 has a movable gap in the vertical direction with the steel sleeve 1. The specific size of the opening can be set according to whether there is a vertical limiting requirement. The width of the opening is p, as shown in Figures 5-6 . If there is no vertical limiting requirement, the width of the opening is adapted to the width b of the rod body 33, that is, p is b+1~2mm, the connecting piece 3 can be placed in the opening, but p is smaller than the width Ly of the first connecting end 31. The width of the notch of the steel sleeve 1 towards the connecting piece 3 is wider than p, which meets the longitudinal displacement requirement, but is also smaller than the width Ly of the first connecting end 31, so as to avoid the connecting piece 3 from being pulled out of the steel sleeve 1.

[0050] Embodiment 2

[0051] The anti-falling beam device for a bridge in a seismic area according to the present application is substantially the same as that in Embodiment 1. The difference lies in that when vertical limiting is required, as shown in Figures 7-8 , the width p of the opening meets tw <p< Ly , tw , which represents the thickness of the rod body 33, Ly , which represents the width of the first connecting end 31, facilitates the rod body 33 to be placed in the steel sleeve 1 sideways and then be rotated by 90° for fixation, which is convenient for installing the anti-falling beam device and can also be vertically limited to adapt to the anti-falling beam requirements in high-intensity seismic areas, such as a 9-degree seismic area and a near-active fault area.

[0052] Embodiment 3

[0053] The design method of the anti-falling beam device of the bridge in the earthquake area, applied to the anti-falling beam device of the bridge in the earthquake area as described in Embodiment 1, comprises the following steps:

[0054] a. According to the preset seismic wave at the bridge site, the horizontal seismic force borne by the anti-falling beam device is determined F he ; According to the distance between the steel sleeve 1 and the edge of the support cushion stone 4 dx The length of each connecting piece 3 is determined L and the outer diameter D and the inner diameter d of the steel sleeve 1 are determined, and according to the length of each connecting piece 3 L The horizontal seismic force borne by the corresponding connecting piece 3 is determined F hei ;

[0055] b. According to Ly =d-2a, the width of the first connecting end 31 is determined Ly , a represents the longitudinal displacement requirement of the connecting piece 3; according to F he / (( Ly -2×π×d1 2 / 4)× tg) ≤[σ] to determine the thickness of the second connecting end 32 tg , [σ] represents the tensile allowable stress of the second connecting end 32, and d1 represents the diameter of the connecting part of the second connecting end 32 and the beam body 2; the first thickness of the first connecting end 31 is determined t 1, and then according to hw=L - t 1- tg The length of the rod body 33 is calculated hw ;

[0056] The connecting piece 3 and the beam body 2 are connected by bolts, and the number n of the bolts and the diameter d of the bolts l and the force requirement are F he / (n×π×d l 2 / 4)≤[σ l ], [σ l ] is the allowable tensile stress of the bolt, and d l can be selected, and then the required number of bolts is calculated. Since a row of U-shaped bolts is 2, the required number of rows of bolts is determined.

[0057] According to the principle of simplifying the material size, the first thickness t 1 can be determined as equal to the thickness of the second connecting end 32 tg .

[0058] c. According to tw ≥ hw / 160 Determine the thickness of the rod body 33 tw , according to b≥ F he / ([σ]× tw ) Determine the width b of the rod body 33

[0059] d, according to F he / (2× t 2× tw )≤ Determine the second thickness of the first connecting end 31 t 2, Indicates the shear requirement of the first connecting end 31, if t 2≤ t 1, the thickness of the first connecting end 31 is taken t 1, and then according to (Ly-b) / 2 t 1≤13 Check the width of the first connecting end 31 Ly , if Ly satisfy the requirements, complete the size determination of the connecting piece 3;

[0060] The width of the rod body 33 calculated above is the minimum size of the equal section. In the shock energy dissipation design, the middle section is determined according to the above size, and the size near the first connecting end 31 and the second connecting end 32 is larger than that of the middle section, so that the middle section first reaches the material stress and enters the plastic stage to deform and dissipate energy in the earthquake.

[0061] It can also be adjusted t 1 to optimize, and then repeat step d to check, so as to reduce the size of the component and save materials.

[0062] e, according to W=π×(D 4 -d 4 ) / 32D, determine whether the wall thickness (D-d) / 2 of the steel sleeve 1 meets the stress requirement, wherein σ=M / W≤[σ], M is the bending moment of the steel sleeve 1 under the most unfavorable working condition in the earthquake, M= F hei ×H; H is the distance from the center of the rod body 33 to the top of the pier, W is the sectional modulus of the steel sleeve 1, σ is the bending stress of the steel sleeve 1, and [σ] is the allowable bending stress of the steel sleeve 1 material; If D and d meet the stress requirement, the size determination of the steel sleeve 1 is completed; then according to Check whether the length of the connecting piece 3 meets the requirements L , wherein E g is the elastic modulus of the steel sleeve 1, I g is the sectional moment of inertia of the steel sleeve 1, Ig=π×D 4 ×(1-(d / D) 4 ) / 64, H is the distance from the center of the rod body 33 to the top of the pier,hd For the thickness of the bearing cushion stone 4, according to Check the horizontal seismic force borne by the corresponding connecting piece 3 F hei Whether the requirements are met, wherein, , i m The area linear stiffness of the connecting piece 3 is represented by i mi The area linear stiffness of the first i connecting piece 3 is represented by E i The elastic modulus of the first i connecting piece 3 is represented by A i The cross-sectional area of the first i connecting piece 3 is represented by A1; if L and F hei Both requirements are met, the design of the anti-falling beam device is completed.

[0063] If a single layer cannot meet the stress in the direction of the beam height, multiple connecting pieces 3 can be arranged in the direction of the beam height according to the needs, at this time the seismic force is evenly divided according to the number of connecting pieces 3. See Figure 9 .

[0064] If the bridge site is located in a 9-degree seismic fortification zone, that is, the anti-falling beam device of a bridge in a seismic zone as applied in Example 2, in step a, the vertical seismic force borne by the anti-falling beam device F se and the vertical seismic force borne by the corresponding connecting piece 3 F sei ; In step e, the bending moment of the steel sleeve 1 under the most unfavorable working condition under the earthquake is replaced by M= F hei ×H+ F sei ×D / 2, the bending stress of the steel sleeve 1 is replaced by σ=(M / W+ F sei / A)≤[σ], and the shear resistance requirement and F sei , F sei / ((b- tw )× tw )≤ , wherein A=π×D 2 ×(1-α 2 ) / 4, A is the cross-sectional area of the steel sleeve 1, and α=d / D; , wherein, , i iThis indicates the moment of inertia linear stiffness of connector 3. i ii Indicates the first i The moment of inertia linear stiffness of connector 3, E i Indicates the first i The elastic modulus of connector 3, I i Indicates the first i The moment of inertia of the cross section of connector 3.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of designing a fall prevention device for a bridge in a seismic zone, characterized in that, The anti-falling beam device of the bridge in the earthquake zone comprises a steel sleeve (1) located on at least one side of a beam body (2), the steel sleeve (1) has a spacing with a support abutment (4) of the corresponding side, the steel sleeve (1) and the beam body (2) are connected through a connecting piece (3), the connecting piece (3) comprises a first connecting end (31), a second connecting end (32) and a rod body (33) between the two, the first connecting end (31) is connected in the steel sleeve (1), the second connecting end (32) is connected with the beam body (2); the cross-sectional size of the first connecting end (31) and the second connecting end (32) is greater than the cross-sectional size of the rod body (33), and / or the elastic modulus of the first connecting end (31) and the second connecting end (32) is greater than the elastic modulus of the rod body (33), and the design method comprises the following steps: a. The horizontal seismic force that the anti-falling beam device bears is determined according to the preset seismic wave at the bridge site F he ; The distance between the steel sleeve (1) and the edge of the abutment cushion stone (4) dx The length of each connecting piece (3) is determined L The outer diameter D and the inner diameter d of the steel sleeve (1) are determined, and the length of each connecting piece (3) is determined L The horizontal seismic force that the corresponding connecting piece (3) bears is determined F hei ; b. according to Ly = d - 2a determine the width of the first connecting end (31) Ly , a represents the longitudinal displacement requirement of the connecting piece (3); according to F hei / (( Ly - 2 x pi x d1 2 / 4) x tg) ≤ [σ] determine the thickness of the second connecting end (32) tg , [σ] represents the tensile allowable stress of the second connecting end (32), d1 represents the diameter of the connecting part of the second connecting end (32) and the beam body (2); the first thickness of the first connecting end (31) is determined t 1, then according to hw=L - t 1- tg calculate the length of the rod body (33) hw ; c. according to tw ≥ hw / 160 determine the thickness of the rod (33) tw , according to b≥ F hei / ([σ] x tw ) determine the width b of the rod (33); d. According to F hei (2 x t 2 x tw )≤ determining the second thickness of the first connecting end (31) t 2, represents the shear allowable stress of the first connecting end (31), if t 2≤ t 1, the thickness of the first connecting end (31) is taken t 1, and then according to (Ly-b) / 2 t 1≤13 to calculate the width of the first connecting end (31) Ly , if Ly satisfy the requirements, the size of the connecting piece (3) is determined; e. According to W=π×(D) 4 -d 4 ) / 32D, determine whether the wall thickness (Dd) / 2 of the steel sleeve (1) meets the stress requirements, where σ=M / W≤[σ], M is the bending moment of the steel sleeve (1) under the most unfavorable working condition under earthquake, M= F hei ×H; H is the distance from the center of the rod (33) to the top of the pier, W is the section modulus of the steel sleeve (1), σ is the bending stress of the steel sleeve (1), and [σ] is the allowable bending stress of the material of the steel sleeve (1); if D and d both meet the stress requirements, then the dimensions of the steel sleeve (1) are determined; then according to Verify the length of connector (3) L Does it meet the requirements, where E g I is the elastic modulus of the steel sleeve (1). g Let Ig be the moment of inertia of the cross section of the steel sleeve (1), and Ig = π × D. 4 ×(1-(d / D) 4 ) / 64, H is the distance from the center of rod (33) to the top of the pier. hd The thickness of the bearing pad (4); according to Verify the horizontal seismic force borne by the corresponding connector (3). F hei Does it meet the requirements, among which, , i m This indicates the area linear stiffness of the connector (3). i mi Indicates the first i The area linear stiffness of each connector (3), E i Indicates the first i The elastic modulus of each connector (3), A i Indicates the first i The cross-sectional area of ​​each connector (3); if L and F hei If all requirements are met, the design of the anti-falling beam device is complete.

2. The method of designing a seismic bracing system for a bridge according to claim 1, wherein The first connecting end (31) and the steel sleeve (1) have a movable gap in the longitudinal bridge direction and / or the transverse bridge direction.

3. The method of designing a seismic bracing system for a bridge according to claim 2, wherein The top end of the steel sleeve (1) has an opening for placing the connecting piece (3), and the first connecting end (31) and the steel sleeve (1) have a movable gap in the vertical direction.

4. The method of designing a seismic bracing system for a bridge according to claim 3, wherein The width of the opening is p, tw p < p < p Ly .

5. The method of designing a seismic bracing system for a bridge according to any one of claims 1 to 4, wherein The steel sleeve (1) is connected to a top cap steel bar, and the second connecting end (32) is connected to the steel bar of the beam body (2) through a U-shaped bolt.

6. The method of designing a seismic bracing system for a bridge according to any one of claims 1 to 4, wherein When the cross-sectional size of the first connecting end (31) and the second connecting end (32) is greater than the cross-sectional size of the rod body (33), the thickness of the first connecting end (31) and the second connecting end (32) is greater than the thickness of the rod body (33).

7. The method of designing a seismic bracing system for a bridge according to any one of claims 1 to 4, wherein, The anti-falling beam device is provided in the longitudinal bridge direction, and the stiffness of at least two anti-falling beam devices is different.

8. The method of designing a seismic bracing system for a bridge according to claim 3, wherein The width p of the opening is determined in accordance with the width b or thickness t of the stem (33) tw determined.

9. The method of designing a seismic bracing system for a bridge according to any one of claims 1 to 4, wherein, If the bridge site is located in a seismic fortification zone of intensity 9, then step a also includes determining the vertical seismic force that the anti-falling beam device will withstand. F se Vertical seismic force borne by the corresponding connecting piece (3) F sei In step e, the bending moment of the steel sleeve (1) under the most unfavorable working condition during the earthquake is replaced by M= F hei ×H+ F sei ×D / 2, the bending stress of the steel sleeve (1) is replaced by σ=(M / W+ F sei / A)≤[σ], and verify the shear resistance requirement. and F sei , F sei / ((b- tw )× tw )≤ Where A = π × D 2 ×(1-α 2 ) / 4, A is the cross-sectional area of ​​the steel sleeve (1), α=d / D; ,in, , i i Indicates the moment of inertia linear stiffness of connector (3), i ii Indicates the first i The moment of inertia linear stiffness of each connector (3), E i Indicates the first i The elastic modulus of each connector (3), I i Indicates the first i The moment of inertia of the cross section of the connector (3).

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