A fault-crossing suspension bridge dislocation coordinated defense system based on load path reconstruction and a design method thereof

Abstract

This invention relates to the field of seismic design technology for bridge engineering, and discloses a dislocation cooperative defense system and its design method for cross-fault suspension bridges based on load path reconstruction. The system includes a dislocation cooperative locking device located at the mid-span of the main span, connecting the stiffening girder and the main cable. This device maintains a rigid cooperative relationship between the stiffening girder and the main cable in the longitudinal direction when permanent fault displacement occurs, forcing them to translate synchronously to reconstruct the longitudinal load transfer path under cross-fault conditions. A high-frequency aftershock energy dissipation device, a velocity-dependent damping structure, is located at the connection between the bridge tower and the stiffening girder. This device provides energy dissipation during mid-to-high frequency inertial vibrations caused by the superposition of fault displacement and ground motion. By constructing a dual defense mechanism of dislocation cooperative locking and high-frequency aftershock energy dissipation, this invention actively reconstructs the load transfer path under extreme conditions, utilizing the main cable and anchorage system to bear the fault dislocation load, thereby protecting the bridge tower from catastrophic damage.

Description

Technical Field

[0001] This invention relates to the field of seismic design technology for bridge engineering, and in particular to a fault-based collaborative dislocation prevention system and its design method for cross-fault suspension bridges based on load path reconstruction. Background Technology

[0002] With the increasing number of long-span bridges under construction, many planned and under-construction extra-long-span suspension bridges inevitably cross active fault zones with extremely complex geological conditions. Traditional seismic design mainly focuses on the inertial vibration effect caused by seismic waves, while structures crossing active fault zones must also face the permanent large deformation of the ground surface caused by coseismic fault displacement.

[0003] Although suspension bridges are generally considered to have good seismic resistance, historical earthquake damage shows that they still have significant shortcomings in responding to relative foundation displacement and local connection failure. For example, the 1995 Kobe earthquake in Japan caused a longitudinal permanent tensile crack of more than 1 meter between the anchorages on both sides of the Akashi Kaikyo Bridge, directly altering the bridge's geometry; in 1989, the San Francisco Bay Bridge in the United States suffered a catastrophic beam collapse due to excessive support displacement, and some dampers and connecting bolts of the suspension bridge also suffered shear failure. It is evident that in the face of meter-level fault dislocations, traditional protection strategies relying on support sliding or expansion joint deformation are completely ineffective, and the structure must possess the ability to maintain its integrity under extreme displacement.

[0004] However, existing seismic resistance technologies (such as the sacrificial central buckle damping system disclosed in CN202110665926.2) have serious mechanistic flaws when dealing with such disasters. Their intention is to sever the central buckle during strong earthquakes to reduce vibration, which is effective under ordinary earthquakes. However, in cross-fault dislocation scenarios, if the central buckle breaks (sacrifices), the main beam will lose its only strong longitudinal constraint. At this point, the foundation moves several meters with the ground surface, while the main beam remains in place due to inertial lag. This phenomenon of the pier moving while the beam remains stationary will directly lead to a huge shear difference between the tower and the beam, repeating the tragedy of the aforementioned earthquake damage. Therefore, how to construct a synergistic system that can both resist ground tearing and dissipate inertial energy is a pressing technical challenge that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a fault-coordinated defense system and its design method for cross-fault suspension bridges based on load path reconstruction. By constructing a dual defense mechanism of fault coordinated locking and high-frequency aftershock energy dissipation, the load transfer path under extreme conditions is actively reconstructed, and the main cable and anchorage system are used to bear the fault fault load, thereby protecting the bridge tower from devastating damage.

[0006] To achieve the above objectives, the following technical solution is adopted: In a first aspect, the present invention provides a fault-coordinated defense system for cross-fault suspension bridges based on load path reconstruction, which is deployed on a site containing active fault zones / fault lines, and its structural foundation is a foundation that may cause permanent dislocations; the system includes the main structure of the suspension bridge, as well as a fault-coordinated locking device and a high-frequency aftershock energy dissipation device integrated in the main structure. The main structure of the suspension bridge includes a stiffening girder, bridge towers, main cables, suspenders, and anchorages. The main cables are erected on the bridge towers and anchored to the anchorages at both ends. The stiffening girder is suspended below the main cables by the suspenders. The dislocation coordination locking device is located at the mid-span of the main span. The dislocation coordination locking device includes a main cable clamp assembly, a beam end anchorage base, and a rigid force transmission component connecting the two. The main cable clamp assembly is fixedly connected to the main cable, and the beam end anchorage base is fixedly connected to the stiffening girder. The two ends of the rigid force transmission component are connected to the main cable clamp assembly and the beam end anchorage base respectively through fully rigid nodes. The dislocation coordination locking device is used to maintain the rigid coordination relationship between the stiffening girder and the main cable in the longitudinal direction of the bridge in a non-sacrificial manner when a permanent fault displacement occurs. The high-frequency aftershock energy dissipation device is installed between the bridge tower and the stiffening beam, and the high-frequency aftershock energy dissipation device is a velocity-dependent damping structure.

[0007] As a preferred embodiment, the dislocation cooperative locking device has a longitudinal critical locking stiffness threshold determined based on the longitudinal dislocation component along the bridge of the designed fault, and maintains an un-unlocked and un-yielded working state within the range of the longitudinal critical locking stiffness threshold.

[0008] As a preferred embodiment, the longitudinal critical locking stiffness threshold of the dislocation cooperative locking device is determined based on the sensitivity of the bridge tower internal forces to the longitudinal cooperative constraint, and satisfies the following: when the stiffness of the locking device reaches the threshold, under the action of the designed fault dislocation, the proportion of the longitudinal unbalanced force transmitted by the locking device to the longitudinal unbalanced force of the entire bridge is not less than 70%.

[0009] As a preferred embodiment, the system possesses a frequency domain-spatial domain decoupling control mechanism, which includes: for quasi-static fault slip in the 0Hz to 0.5Hz frequency band, the dislocation cooperative locking device provides longitudinal static constraint, and the high-frequency aftershock energy dissipation device basically does not participate in the force; for seismic inertial oscillations with frequencies above 0.5Hz, the high-frequency aftershock energy dissipation device provides velocity-related damping force.

[0010] As a preferred embodiment, the high-frequency aftershock energy dissipation device adopts a velocity index. The nonlinear viscous damper with a damping force of less than 1.0 has a maximum output damping force less than the yield load of the dislocation cooperative locking device.

[0011] As a preferred embodiment, the rigid force transmission component is composed of multiple high-strength steel tie rods or steel profiles, with its slenderness ratio controlled within the range to prevent buckling under compression; or, the rigid force transmission component adopts prestressed high-strength steel wire bundles arranged in an X-shape.

[0012] As a preferred embodiment, the dislocation cooperative locking device is configured as a hinged or flexible connection structure in the transverse bridge direction.

[0013] Secondly, the present invention provides a design method for a fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction as described above, comprising the following steps: Obtain the parameters of the fault zone at the bridge site and the angle between the fault strike and the bridge axis, and extract the dislocation component along the bridge direction; synthesize the time history of near-fault ground motion along the bridge direction containing the set dislocation magnitude. A finite element model was established, and a pure dislocation displacement load was applied. The bending safety factor of the tower bottom section was used as the objective function to calculate the sensitivity curve of the tower bottom bending moment to the central clamp stiffness. The stiffness corresponding to the inflection point of the curve was selected as the design stiffness of the dislocation cooperative locking device. Based on the design stiffness, the synthetic ground motion time history is applied, and the damping coefficient and velocity index of the high-frequency aftershock energy dissipation device are optimized with the longitudinal displacement at the end of the main beam and the displacement at the top of the bridge tower as the constraint targets. The study aimed to verify whether the cross section at the base of the bridge tower remained in a plastically controllable state under the coupled action of maximum dislocation and strong earthquake, and whether the locking device did not break.

[0014] As a preferred embodiment, the inflection point determination criterion of the sensitivity curve is as follows: when the decrease in the bending moment at the bottom of the tower is less than 2% for every 10% increase in the central clamping stiffness, it is determined that the stiffness saturation point has been reached, and the stiffness corresponding to this point is the optimal locking stiffness.

[0015] The beneficial effects of this invention are reflected in: (1) Active reconfiguration of load transfer path: Unlike the traditional design where bridge towers passively bear the tearing force of faults, this invention integrates the stiffening girder and main cable into a co-deformable body through the rigid coupling effect of the dislocation cooperative locking device. At the moment of fault displacement, the enormous longitudinal unbalanced force is actively guided to the main cable-anchorage system, which has extremely high load-bearing capacity, successfully avoiding the relatively weak bending capacity of the bridge towers, fundamentally solving the problem of tower collapse in cross-fault suspension bridges.

[0016] (2) A dual decoupling mechanism in the frequency domain and spatial domain was established: Utilizing the difference in frequency domain between fault dislocations (low frequency / large displacement) and ground motion (high frequency / reciprocating velocity), an orthotropic defense mechanism of rigid locking to resist dislocation and flexible damping to dissipate aftershocks was constructed. For low-frequency quasi-static large dislocations, the dislocation-coordinated locking device provides absolute stiffness to prevent the structure from disintegrating due to incoordination of surface deformation; for high-frequency inertial vibrations, the high-frequency aftershock energy dissipation device provides high damping to dissipate the seismic wave energy accompanying the dislocation, thereby solving the technical problems that a single damper cannot resist static dislocations and a single central buckle cannot dissipate dynamic energy.

[0017] (3) Sensitivity-based intelligent stiffness optimization: Abandoning the empirical and blind approach of traditional central buckle stiffness design, a stiffness determination method based on the inflection point of tower internal force sensitivity is proposed. This ensures that the locking device can provide sufficient load-bearing capacity to achieve load path reconstruction (transmission efficiency >70%), while avoiding material waste or local stress concentration caused by excessive stiffness, thus achieving the best balance between economy and safety. Attached Figure Description

[0018] Figure 1 A schematic diagram of the overall layout of a cross-fault suspension bridge dislocation collaborative defense system based on load path reconstruction, provided for an embodiment of the present invention; Figure 2 This is a functional diagram of a dislocation collaborative locking device in a cross-fault suspension bridge dislocation collaborative defense system based on load path reconstruction, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram illustrating the overall structural working principle of a cross-fault suspension bridge dislocation collaborative defense system based on load path reconstruction, provided in an embodiment of the present invention. Figure 4 A design flowchart of a cross-fault suspension bridge dislocation collaborative defense system based on load path reconstruction is provided for an embodiment of the present invention. Figure 5 The flowchart illustrates a design method for a cross-fault suspension bridge dislocation collaborative defense system based on load path reconstruction, as provided in an embodiment of the present invention.

[0019] Figure label: 1. Active fault zone / fault line; 2. Foundation; 3. Anchorage; 4. Bridge tower; 5. Main cable; 6. Stiffening girder; 7. Suspension cable; 10. Dislocation cooperative locking device; 11. Main cable clamp assembly; 12. Beam end anchorage base; 13. Rigid force transmission assembly; 14. Fully rigid node; 20. High-frequency aftershock energy dissipation device. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0022] Example 1: This invention provides a collaborative dislocation prevention system for cross-fault suspension bridges based on load path reconstruction, such as... Figure 1 and Figure 2 As shown, the system is deployed on a site containing an active fault zone / fault line 1, and its structural foundation is a foundation 2 where permanent dislocation may occur. The system includes the main structure of the suspension bridge, as well as a dislocation coordination locking device 10 and a high-frequency aftershock energy dissipation device 20 integrated into the main structure. The main structure of the suspension bridge includes a stiffening girder 6, a bridge tower 4, a main cable 5, a suspension cable 7, and anchorages 3. The stiffening girder 6 is suspended below the main cable 5 by the suspension cable 7. The main cable 5 is erected on the bridge tower 4 and anchored to the anchorages 3 at both ends. The dislocation coordination locking device 10 is set at the mid-span of the main span. Its two ends are fixedly connected to the main cable 5 and the main girder 6 through the main cable clamp assembly 11 and the beam end anchorage base 12, respectively. It is used to maintain the rigid coordination relationship between the stiffening girder 6 and the main cable 5 in the longitudinal direction in a non-sacrificial manner when permanent fault displacement occurs, and to force the two to undergo overall synchronous translation under the action of fault dislocation, thereby reconstructing the longitudinal load transfer path under the fault condition. The high-frequency aftershock energy dissipation device 20 is installed at the connection between the bridge tower 4 and the stiffening girder 6. It is a velocity-dependent damping structure, which does not produce significant damping during the low-velocity quasi-static displacement caused by the permanent fault dislocation, but provides energy dissipation capacity during the medium- and high-frequency inertial vibration caused by the superimposed ground motion of the fault displacement. Among them, the dislocation cooperative locking device 10 has a longitudinal stiffness threshold determined based on the longitudinal dislocation component of the designed fault along the bridge. Within the threshold range, it maintains an unlocked and unyielding working state, so that the longitudinal unbalanced force caused by the fault dislocation is preferentially transmitted through the main cable-stiffening girder system, rather than concentrated in the bridge tower structure.

[0023] In some embodiments, such as Figure 1 As shown, the longitudinal critical locking stiffness threshold of the dislocation cooperative locking device 10 K minBased on the sensitivity of the bridge tower internal forces to longitudinal coordinating constraints, and satisfying the following load transfer efficiency conditions: when the stiffness of the locking device reaches the threshold, under the action of the design fault dislocation, the proportion of the longitudinal unbalanced force transmitted by the locking device to the longitudinal unbalanced force of the whole bridge is not less than 70%, so as to ensure that the longitudinal load under the fault crossing condition is transformed from tower-controlled transmission to cable-beam coordinating transmission.

[0024] In some embodiments, the system has a frequency-spatial decoupling control mechanism for permanent fault dislocations and seismic inertial responses: ① In the spatial dimension, for quasi-static fault slip in the 0Hz to 0.5Hz frequency band, the dislocation co-locking device 10 provides longitudinal static constraint, at which time the high-frequency aftershock energy dissipation device 20 basically does not participate in the force due to insufficient relative velocity, allowing the stiffening girder 6 to undergo coordinated deformation with the bridge tower 4; ② In the frequency dimension, for seismic inertial oscillations with frequencies above 0.5Hz, the high-frequency aftershock energy dissipation device 20 provides velocity-related damping force to suppress the longitudinal vibration of the stiffening girder 6 and the inertial amplification effect at the top of the bridge tower 4.

[0025] In some embodiments, the high-frequency aftershock energy dissipation device 20 employs a velocity index. Nonlinear viscous damper with a damping force <1.0; its maximum output damping force F Dmax Set to less than the yield load of the dislocation co-locking device F ylock This ensures that, under the superposition of extremely rare earthquakes and maximum dislocations, the energy dissipation path will not induce premature failure of the locking device.

[0026] In some embodiments, such as Figure 2 As shown, the specific structure of the dislocation cooperative locking device 10 includes: a rigid connection assembly, one end of which is anchored to the main cable clamp assembly 11, and the other end of which is anchored to the main truss node of the stiffening beam 6; the rigid connection assembly is composed of multiple high-strength steel tie rods or steel sections, and its slenderness ratio is controlled within the range to prevent buckling under compression; or, the rigid connection assembly adopts prestressed high-strength steel wire bundles arranged in an "X" shape to provide bidirectional symmetrical longitudinal constraint stiffness, and the dislocation cooperative locking device is configured as a hinged or flexible connection structure in the transverse direction of the bridge to accommodate possible transverse displacement components.

[0027] like Figure 3The diagram shows the overall structural working principle of the fault-based dislocation co-fortification system for cross-fault suspension bridges. It first receives the input of a cross-fault earthquake coupled with a disaster, and then, through an input separation response mechanism (frequency-spatial decoupling), decomposes it into a low-frequency / quasi-static component (large dislocations along the bridge direction) and a high-frequency / dynamic component (inertial vibration). For the low-frequency / quasi-static component, the dislocation co-locking device maintains a rigidly locked state—non-yielding, non-melting, and non-unlocking—based on a stiffness critical threshold. This, in turn, forms a "static bearing effect" through load path reconstruction and forced traction. The system enables the main beam to move with the foundation, transmits force to the main cable-anchor system, and eliminates harmful shear force differences at the tower base. For high-frequency / dynamic components, the high-frequency aftershock energy dissipation device maintains a viscous energy dissipation state without failure, load shedding, or slippage based on the velocity activation threshold. Through a directional energy dissipation mechanism, a "dynamic dissipation effect" is formed, which specifically suppresses high-frequency vibration and residual displacement of the beam and controls the "whiplash effect" at the top of the tower. Finally, the dislocation coordination locking device and the high-frequency aftershock energy dissipation device system work together to minimize the relative displacement between the tower and the beam, thereby ensuring that the bridge does not collapse, the main beam does not fall, and traffic is maintained after the earthquake.

[0028] Example 2: This invention provides a design method for a fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction, as described in any embodiment of Embodiment 1. Figure 4 As shown, the overall technical approach of this design method is as follows: First, S1 input source synthesis is performed to obtain fault zone parameters. Based on these parameters, the longitudinal dislocation components are calculated, and then the near-fault ground motion time history is synthesized. Next, the S2 stiffness optimization stage is entered. A finite element model is established and dislocation loads are applied to it. The sensitivity curve of the tower base bending moment to stiffness is calculated, and the optimal stiffness K is determined by locating the inflection point of this curve. Then, S3 dynamic parameter matching is performed. The synthesized ground motion time history is applied to the model, and the damper parameters (C, ...) are optimized with beam end displacement and tower top displacement as dual objectives. α Finally, the S4 failure mode verification is performed: first, a coupled analysis of maximum dislocation and strong earthquake is conducted to verify two key indicators—1. whether the bridge tower root exhibits "strong shear and weak bending"; 2. whether the locking device has not broken. The verification is then judged to see if it passes. If it fails, the process is reverted to earlier adjustments; if it passes, the design is completed.

[0029] Specifically, such as Figure 5 As shown, the design method may include the following steps S10-S40.

[0030] S10: Obtain the parameters of the fault zone at the bridge site and the angle between the fault strike and the bridge axis, and extract the dislocation component along the bridge direction; synthesize the time history of near-fault ground motion along the bridge direction containing the set dislocation magnitude.

[0031] In this embodiment, the purpose of step S10 is to synthesize the input source. By obtaining the fault zone parameters at the bridge site and the angle between the fault strike and the bridge axis, the bridge-direction component of the total fault displacement is extracted. The directional model is used to simulate the velocity pulse, and the slip-thrust effect model is superimposed to simulate the permanent surface displacement, so as to synthesize the bridge-direction near-fault ground motion time history containing a specific displacement level.

[0032] In some embodiments, step S10 may be implemented through the following steps: S101: Obtain the parameters and included angle of the fracture zone.

[0033] Core parameters of the fault zone were obtained through 1:5000 geological mapping, borehole exploration, and magnetotelluric surveys in the bridge site area, including: fault type (normal fault / reverse fault / strike-slip fault) and total displacement. (Unit: m) Fault dip angle θ (Unit: °), sliding angle ϕ (Unit: °); By comparing GPS positioning with the bridge axis design drawings, the angle between the fault strike and the bridge axis was measured. a (Unit: °), measurement deviation is controlled within ±0.5°.

[0034] All parameters need to be cross-validated in conjunction with the regional seismic geological survey report to ensure the total displacement. The value should be no less than the dislocation magnitude corresponding to an extremely rare earthquake with a 50-year exceedance probability of 2% in the fault zone.

[0035] S102: Calculate the bridging dislocation components.

[0036] The bridging dislocation components are extracted using the vector projection method. The formula is as follows: in, The angle between the fault slip direction and the fault strike (unit: °) is taken as 0° for translational faults and 90° for normal / reverse faults; the calculation accuracy is controlled within 0.01m. If the calculation result is less than 0.5m, the value is taken as 0.5m (considering the minimum design displacement level).

[0037] S103: Synthetic near-fault ground motion time history. The time history is synthesized using the superposition method of velocity pulses and sliding displacements. The specific process includes: S1031: Use a modified pulse model to generate velocity pulse time histories. v p ( t The formula is as follows: in: The peak velocity is the pulse velocity (unit: m / s), based on the peak ground acceleration at the bridge site. a max (Taken from GB18306-2015) Calculation, =0.8× a max × T p ; The pulse start time (in seconds) is 0.5 to 1.0 seconds. The pulse decay time (in seconds) is taken as 2 × Tp; The pulse period (unit: seconds) is determined based on the distance between the fault and the bridge site. R Sure: R For distances ≤ 5km, Tp = 1.5~2.5s; for distances < 5km, Tp = 1.5~2.5s. R ≤10km =1.0~1.5s.

[0038] S1032: Generating the time history of sliding displacement using a bilinear model The formula is as follows: us(t)=Dlong×[1−exp(−Tst)] in: The rise time of the thrust displacement (unit: s) is taken as 5~10sm, and adjusted according to the fault type: 5~7s for strike-slip faults, and 7~10s for normal / reverse faults. Sliding displacement time history It must satisfy: as t→∞, the slip stroke→ Furthermore, the peak acceleration during the ascent phase does not exceed 0.1g, where g is the gravitational acceleration, taken as 9.81 m / s². 2 .

[0039] S1033: Transmit velocity pulse time history v p ( t Integrating the pulse displacement time history yields the result. u p ( t ), and the time history of sliding displacement Superposition yields the original seismic motion displacement time history. u raw (t)= u p ( t )+ u s ( t );rightu raw (t) Filtering was performed (using a Butterworth low-pass filter with a cutoff frequency of 20Hz) to remove high-frequency noise; the time history length was adjusted to 30~60s (including the first 5s of static segment to ensure stable dynamic response), and finally the time history of near-fault ground motion along the bridge direction was obtained. u ( t Its peak displacement error is controlled within ±5%.

[0040] S20: Establish a finite element model, apply pure dislocation displacement load, use the bending safety factor of the tower bottom section as the objective function, calculate the sensitivity curve of the tower bottom bending moment to the central clamping stiffness, and select the stiffness corresponding to the inflection point of the curve as the design stiffness of the dislocation cooperative locking device.

[0041] In this embodiment, the purpose of step S20 is to achieve locking stiffness optimization.

[0042] In some embodiments, step S20 may be implemented through the following steps: S201: Establish the finite element model of the entire bridge.

[0043] The model is built using general-purpose finite element software (such as ANSYS or MidasGen), and the model accuracy must meet the engineering design requirements. The element selection and parameter settings are shown in Table 1.

[0044] Table 1 Unit Selection and Parameter Settings

[0045] Set the boundary conditions as follows: Anchorage: Fixed constraint (displacement in the X, Y, and Z directions is all 0); Bridge tower foundation: Fixed constraints (considering the foundation stiffness, springs can be used for simulation, with a stiffness of 1×10⁻⁶). 7 kN / m); Stiffening beam and support: Hinged connection, only transmitting vertical force.

[0046] S202: Apply pure dislocation displacement load.

[0047] The model simulates permanent fault dislocations. A longitudinal displacement load is applied at the anchorage on one side of the fault, with the load magnitude equal to that calculated in step S10. D long The loading method is to apply static load slowly for 10 seconds to avoid dynamic effects.

[0048] S203: Calculate the bending moment sensitivity curve at the bottom of the tower.

[0049] Safety factor for bending resistance at the base of the tower K mLet the objective function be the formula, as follows: in: The ultimate flexural bearing capacity of the tower base section (unit: kN·m) is calculated according to the "Design Specification for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" JTG3362-2018: The bending moment (unit: kN·m) at the bottom section of the tower under pure dislocation load is calculated and directly output from the finite element model.

[0050] S204: Calculate sensitivity.

[0051] Setting the stiffness variable of the locking device K initial value K 0 = 1 × 10 4 kN / m, increasing by 10% each time (i.e. K i+1 =1.1× K i ), until K =1×10 6 kN / m; For each stiffness value K i Solve the finite element model to obtain the corresponding bending moment at the base of the tower. ; Define stiffness sensitivity (Unit: kN·m / (kN / m)), the formula is as follows: With stiffness K The x-axis represents the bending moment at the base of the tower. Plot the ordinate as the vertical axis. - K Sensitivity curve.

[0052] S205: Select the optimal stiffness.

[0053] When stiffness from K i Increase to K i+1 When the increase is 10%, the reduction in the bending moment at the base of the tower is... Determine that K i+1 This is the stiffness saturation point; The stiffness corresponding to this saturation point is the design stiffness of the dislocation cooperative locking device. K design Record this value and verify: at this time, the longitudinal unbalanced force transmitted by the locking device is... Flock Longitudinal unbalanced force of the entire bridge F total The proportion is ≥70%, and the verification formula is as follows: in: The longitudinal displacement of the locking device (unit: m) is output from the finite element model. F total = D long ×( K design + K cable Kcable is the longitudinal equivalent stiffness of the main cable, in kN / m.

[0054] S30: Based on the design stiffness, the synthetic ground motion time history is applied, and the damping coefficient and velocity index of the high-frequency aftershock energy dissipation device are optimized with the longitudinal displacement at the end of the main beam and the displacement at the top of the bridge tower as the constraint targets.

[0055] In this embodiment, the purpose of step S30 is to achieve dynamic parameter matching. Based on the stiffness determined in S20, the synthetic ground motion time history is applied. With the longitudinal displacement at the end of the main beam and the displacement at the top of the bridge tower as dual constraint targets, the damping coefficient and velocity index of the high-frequency aftershock energy dissipation device are optimized using a genetic algorithm or iterative method.

[0056] In some embodiments, step S30 may be implemented through the following steps: S301: Apply dynamic load.

[0057] In the finite element model established in step S20, the design stiffness of the locking device is retained. K design Remove pure dislocation loads; apply the seismic time history synthesized in step S10 to the bridge tower foundation. u ( t The loading method is acceleration time history input. The acceleration time history is obtained by taking the second derivative of the displacement time history and filtering to remove noise. The time step is 0.01s, and the analysis time is consistent with the ground motion time history (30~60s). The Newmark-β method is used to solve the problem, with β=0.25 and γ=0.5.

[0058] S302: Constraint target quantification.

[0059] With the longitudinal displacement at the end of the main beam and the displacement at the top of the bridge tower as dual constraints, the quantitative indicators are as follows (based on the "Code for Seismic Design of Highway Bridges and Culverts" JTG / T2231-01-2020): Allowable longitudinal displacement at the end of the main beam u beam,lim = L / 500,L Main span, unit: m; Allowable longitudinal displacement at the top of bridge tower u tower,lim = H / 300, H The height of the bridge tower is expressed in meters (m).

[0060] S303: Parameter optimization of high-frequency aftershock energy dissipation device based on genetic algorithm.

[0061] S3031: Define optimization variables.

[0062] Damping coefficient C, ranging from 100 to 1000 kN·s n / m (n=α); The velocity index α ranges from 0.3 to 0.9 (satisfying α < 1.0, with a step size of 0.05).

[0063] S3032: Construct the fitness function.

[0064] The fitness function is constructed using a weighted summation method. F The goal is to minimize the displacement deviation: in: Peak longitudinal displacement at the end of the main beam calculated for the model (unit: m); Peak longitudinal displacement at the top of the tower calculated for the model (unit: m); Weight =0.6, =0.4 (Prioritize controlling the displacement of the main beam). When the fitness function value F ≤ 0, the constraint requirements are met.

[0065] S3033: Genetic algorithm parameter settings, as shown in Table 2.

[0066] Table 2 Genetic Algorithm Parameters

[0067] S3034: Execute the optimization process, as follows: 1) Initialize the population: Randomly generate 50 groups ( C , α All parameter combinations are within their range of values; 2) Fitness calculation: For each set of parameters, substitute them into the finite element model for dynamic analysis and calculate... u beam and u tower This leads to the fitness function F; 3) Selection operation: Use roulette wheel selection to select the 20 parameters with the lowest fitness values ​​to enter the next generation; 4) Cross operation: Performs linear cross operation on the selected parameter group. C new =0.7 C 1+0.3 C 2, α new =0.6 α 1+0.4 α 2; 5) Mutation operation: Randomly mutate the parameter set after crossover, with C mutating by ±10%. α Variation range ±0.05; 6) Termination condition: When the number of iterations reaches 100, or the fitness function value shows no significant change (change < 0.01) for 10 consecutive generations, output the optimal parameters. C opt , α opt ).

[0068] S3035: Parameter verification.

[0069] The optimal parameters must satisfy: the maximum output damping force of the high-frequency aftershock energy dissipation device. F Dmax < F ylock ,in: F ylock = σ y × A lock in, v max The peak relative velocity between the tower and beam, in m / s, is output from the dynamic analysis. σ y The yield strength of the locking device material is expressed in MPa. A lock Total cross-sectional area of ​​the locking device, unit: mm 2 .

[0070] S40: Verify whether the cross section at the base of the bridge tower remains in a plastically controllable state under the coupled action of maximum dislocation and strong earthquake, and whether the locking device has broken.

[0071] In this embodiment, the purpose of step S40 is to perform failure mode verification: to verify whether the cross section at the base of the bridge tower remains in a plastically controllable state of "strong shear and weak bending" under the coupled action of maximum dislocation and strong earthquake, and whether the locking device has broken.

[0072] In some embodiments, step S40 may be implemented through the following steps: S401: Apply coupling load.

[0073] In the finite element model, the maximum dislocation displacement and the strong earthquake time history are applied simultaneously, with the maximum dislocation displacement taken as 1.2 × D long (Considering over-design dislocation redundancy); the strong earthquake time history is selected as an extremely rare ground motion time history with a 2% exceedance probability in 50 years (from the same source as the synthesized time history in step S10, with peak ground acceleration amplified by 1.2 times). The loading sequence is to first apply 50% dislocation displacement, and then simultaneously apply the remaining dislocation displacement and the strong earthquake time history, with a total loading time of 60s.

[0074] S402: Verification of the controllability of plasticity of the bridge tower root section.

[0075] Calculate the flexural bearing capacity of the bridge tower root section (1.5 times the tower diameter above the top surface of the foundation). M u and shear bearing capacity V u (Calculations were performed in accordance with JTG 3362-2018).

[0076] Obtain the calculated bending moment of the bridge tower root section under coupled loads output from the finite element model. M cal and calculating shear force V ca ; Verification is performed using the following verification criteria: Bending moment safety factor: The cross-section is allowed to enter the plastic stage, but not exceeding the ultimate bearing capacity; Shear force safety factor: This ensures sufficient shear capacity and achieves strong shear and weak bending. Ductility coefficient: , The maximum rotation angle of the cross section. The yield rotation angle is calculated using the fiber model to ensure that plastic deformation is controllable.

[0077] S403: Strength verification of dislocation cooperative locking device.

[0078] The maximum axial force of the locking device under coupled load was extracted using a finite element model. F lock,max (Tension or compression), unit: kN.

[0079] Tensile stress verification: Considering the dynamic coefficient, we take 0.8 times the yield strength. Compressive stress verification (for members subjected to compression and bending): ; Add a bending moment to the locking device. For section modulus, The moment of inertia of the cross section; Stability verification (for tie rods / steel sections): slenderness ratio λ = l 0 / i ≤[ λ ]; l 0 represents the calculated length. i Let be the radius of gyration of the cross section, [ λ [ ] is the limit value for the slenderness ratio of the compression member, which is taken as 150.

[0080] S404: Verification result determination.

[0081] If the bridge tower root is satisfied K M ≥1.0、 K V ≥1.2、 μ ≥3.0, and locking device σ t ≤0.8 σ y , λ ≤[ λ If the result is positive, the failure mode verification passes. If the requirements are not met, return to step S20 to adjust the stiffness of the locking device or step S30 to optimize the damping parameters, and recalculate until the requirements are met.

[0082] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A fault-resistant suspension bridge dislocation coordinating defense system based on load path reconstruction, deployed on a site containing active fault zones / fault lines (1), its structural foundation being a foundation (2) where permanent dislocations may occur; characterized in that, The system includes the main structure of the suspension bridge, as well as a dislocation cooperative locking device (10) and a high-frequency aftershock energy dissipation device (20) integrated in the main structure. The main structure of the suspension bridge includes a stiffening girder (6), a bridge tower (4), a main cable (5), suspenders (7) and anchorages (3). The main cable (5) is erected on the bridge tower (4) and anchored to the anchorages (3) at both ends. The stiffening girder (6) is suspended below the main cable (5) by the suspenders (7). The dislocation coordination locking device (10) is located at the mid-span of the main span. The dislocation coordination locking device (10) includes a main cable clamp assembly (11), a beam end anchorage base (12), and a rigid force transmission assembly (13) connected between the two. The main cable clamp assembly (11) is fixedly connected to the main cable (5), and the beam end anchorage base (12) is fixedly connected to the stiffening beam (6). The two ends of the rigid force transmission assembly (13) are connected to the main cable clamp assembly (11) and the beam end anchorage base (12) respectively through fully rigid nodes (14). The dislocation coordination locking device (10) is used to maintain the rigid coordination relationship between the stiffening beam (6) and the main cable (5) in the longitudinal direction of the bridge in a non-sacrificial manner when a permanent fault displacement occurs. The high-frequency aftershock energy dissipation device (20) is located between the bridge tower (4) and the stiffening beam (6), and the high-frequency aftershock energy dissipation device (20) is a velocity-dependent damping structure.

2. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 1, characterized in that, The dislocation cooperative locking device has a longitudinal critical locking stiffness threshold determined based on the longitudinal dislocation component along the bridge of the designed fault, and maintains an un-unlocked and un-yielded working state within the range of the longitudinal critical locking stiffness threshold.

3. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 2, characterized in that, The longitudinal critical locking stiffness threshold of the dislocation cooperative locking device (10) is determined based on the sensitivity of the bridge tower internal force to the longitudinal cooperative constraint, and satisfies the following: when the stiffness of the locking device reaches the threshold, under the action of the designed fault dislocation, the longitudinal unbalanced force transmitted by the locking device accounts for no less than 70% of the longitudinal unbalanced force of the whole bridge.

4. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 1, characterized in that, The system has a frequency domain-spatial domain decoupling control mechanism, which includes: for quasi-static fault slip in the 0Hz to 0.5Hz frequency band, the dislocation cooperative locking device provides longitudinal static constraint, and the high-frequency aftershock energy dissipation device basically does not participate in the force; for seismic inertial oscillations with frequencies above 0.5Hz, the high-frequency aftershock energy dissipation device provides velocity-related damping force.

5. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 1, characterized in that, The high-frequency aftershock energy dissipation device (20) adopts a velocity index. The nonlinear viscous damper with a damping force of less than 1.0 has a maximum output damping force less than the yield load of the dislocation cooperative locking device.

6. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 1, characterized in that, The rigid force transmission component (13) is composed of multiple high-strength steel tie rods or steel profiles, with its slenderness ratio controlled within the range to prevent buckling under compression; or, the rigid force transmission component (13) adopts prestressed high-strength steel wire bundles arranged in an X-shape.

7. The fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction according to claim 6, characterized in that, The dislocation cooperative locking device is configured as a hinged or flexible connection structure in the transverse bridge direction.

8. A design method for a fault-resistant suspension bridge dislocation collaborative defense system based on load path reconstruction as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Obtain the parameters of the fault zone at the bridge site and the angle between the fault strike and the bridge axis, and extract the dislocation component along the bridge direction; synthesize the time history of near-fault ground motion along the bridge direction containing the set dislocation magnitude. A finite element model was established, and a pure dislocation displacement load was applied. The bending safety factor of the tower bottom section was used as the objective function to calculate the sensitivity curve of the tower bottom bending moment to the central clamp stiffness. The stiffness corresponding to the inflection point of the curve was selected as the design stiffness of the dislocation cooperative locking device. Based on the design stiffness, the synthetic ground motion time history is applied, and the damping coefficient and velocity index of the high-frequency aftershock energy dissipation device are optimized with the longitudinal displacement at the end of the main beam and the displacement at the top of the bridge tower as the constraint targets. The study aimed to verify whether the cross section at the base of the bridge tower remained in a plastically controllable state under the coupled action of maximum dislocation and strong earthquake, and whether the locking device did not break.

9. The design method according to claim 8, characterized in that, The inflection point determination criterion of the sensitivity curve is: when the decrease in the bending moment at the bottom of the tower is less than 2% for every 10% increase in the central stiffness, it is determined that the stiffness saturation point has been reached, and the stiffness corresponding to this point is the optimal locking stiffness.

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