Bridge transverse quasi-isolation multi-stage ordered anti-seismic construction method

Abstract

The present application relates to the field of bridge seismic resistance technology, in particular to a bridge transverse quasi-isolation multi-stage ordered seismic resistance construction method, according to the seismic resistance requirement of the bridge structure under different intensity grades of earthquakes, the performance target of three levels is determined, the reasonable mechanical parameter value method of steel block is proposed, the multi-stage seismic resistance mechanism of quasi-isolation bridge is established, the seismic potential of each component is sequentially played, the seismic damage degree of the bridge can be controlled and reduced according to the expected performance target, and the falling beam phenomenon of the bridge superstructure can be effectively prevented, so that the multi-stage ordered seismic resistance mechanism is realized.

Description

Technical Field

[0001] This invention relates to the field of bridge seismic resistance technology, and more specifically, to a method for constructing a bridge with lateral quasi-isolation multi-level ordered seismic resistance structure. Background Technology

[0002] Traditional ductile seismic design codes for bridges stipulate that bearing damage is not permitted, and seismic resistance is achieved through the energy dissipation mechanism of pier plastic hinges. Earthquake damage has shown that the code's intended objectives have not been met in actual earthquakes. The frictional slippage of plate rubber bearings creates a natural seismic isolation mechanism. The quasi-seismic isolation design concept, which utilizes the sliding isolation of bearings and the energy dissipation limiting effect of abutments to achieve limited plastic damage to piers and avoid severe damage to the bridge structure, is a current research hotspot. As a key component in achieving this goal, the rational design method of abutments is crucial.

[0003] Currently, due to the lack of design specifications for reinforced concrete abutments, their functional positioning in bridges is unclear, resulting in insufficient seismic resistance. Numerous actual earthquake damages demonstrate that reinforced concrete abutments, due to their high stiffness, low ductility, and lack of energy dissipation capacity, not only hinder the flexibility of plate rubber bearings under seismic loads, increasing the seismic response of the substructure, but also lose their ability to limit the displacement of the main beam and bearings due to brittle shear failure, leading to lateral collapse of the main beam and even severe beam collapse. These traditional reinforced concrete abutments cannot effectively utilize the flexible seismic isolation function of plate rubber bearings and lack sufficient deformation energy dissipation capacity. Although some elastoplastic energy-dissipating steel abutments have been proposed in existing research, they are typically simply applied to bridges for limiting and dissipating energy. However, their application scenarios are relatively limited to different seismic intensities, failing to fully utilize their function for varying random earthquake strengths. The lack of reasonable design methods leads to frequent replacements and low utilization efficiency.

[0004] Currently, the design calculations for quasi-isolation systems of highway bridges typically employ nonlinear seismic response analysis based on elastoplastic finite element models. The parameter values ​​of the steel retainers that meet the design objectives are generally obtained through extensive parameter analysis. This design calculation method has two main shortcomings: 1. Elastoplastic finite element modeling is relatively complex, and nonlinear seismic response analysis is prone to computational convergence problems; 2. The computational workload for determining the design parameters of the steel retainers through parameter analysis is large and time-consuming, making it unsuitable for the design requirements of different types of bridges and hindering its application by designers in practical engineering. These issues urgently need to be addressed in depth. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance, in order to solve the above-mentioned problems in the prior art.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] A method for constructing a bridge with lateral quasi-isolation and multi-stage ordered seismic resistance includes:

[0008] The basic design parameters of the bridge structure are obtained, and three different levels of seismic levels are set according to the seismic intensity. The target performance of the three different levels of seismic levels is confirmed, and the corresponding target spectrum is obtained through the three different levels of seismic levels. The target spectrum is the force-displacement relationship curve.

[0009] The bridge structure is equivalent to an equivalent linear single-degree-of-freedom system (ELSDOF). The force-displacement response curve under elastic state is obtained based on the equivalent ELSDOF system. The force-displacement response curve and demand spectrum curve of the ELSDOF system are established on the same coordinate system to obtain the performance target control points of three different seismic levels.

[0010] The system control points for the three different seismic levels were determined by using performance target control points for three different seismic levels, and the mechanical performance parameters of the steel retaining blocks were obtained.

[0011] The displacement of bridge piers and supports at three levels is calculated by acquiring data from the system control points, thereby obtaining the ductility coefficients of the piers and supports, and determining whether the ductility coefficients of the bridge piers and supports meet the target performance requirements.

[0012] If the conditions are met, the result is output. If not, the mechanical parameters of the selected steel block are readjusted, and the system control points of three different seismic levels are redefined until the ductility coefficients of the bridge piers and supports meet the expected performance requirements. The result is then output.

[0013] Preferably, it also includes obtaining output results that meet the expected target performance requirements, adjusting the mechanical parameters of the steel block based on the output results and the target performance of the current different levels of seismic levels, obtaining the required bridge damage state, and determining whether the mechanical parameters of the steel block need to be readjusted based on the bridge damage state.

[0014] The three different levels of seismic levels include Level 1, Level 2 and Level 3, which have progressively higher seismic intensity; the system control points include the first system control point, the second system control point and the third system control point.

[0015] The first system control point includes:

[0016] Calculate the load on the support constraint system under the target performance of level 10, calculate the total stiffness and strength of the steel block, and the first stiffness of the quasi-isolation system;

[0017] The total displacement of the system below the level is obtained based on the equivalent single-degree-of-freedom and two-degree-of-freedom relationship, and the first system control point is determined.

[0018] Preferably, the calculation of the loads on the support constraint system under the level-10 target performance includes:

[0019]

[0020] In the formula, The yield load of the parallel system of stop blocks and supports. For the quality of the bridge superstructure. For the quality of the bridge substructure. The base shear force of the ELSDOF system below level.

[0021] Preferably, the calculation of the total stiffness of the steel stop block based on the initial performance of the support includes:

[0022]

[0023]

[0024]

[0025]

[0026] In the formula, This refers to the frictional force of the bridge superstructure. The load borne by the steel stop block This represents the number of steel blocks. The yield strength of a single steel block. The total stiffness of the steel stop block, The stiffness of a single steel block;

[0027] The first stiffness of the quasi-isolation system includes:

[0028]

[0029] The total system displacement below the level includes:

[0030]

[0031] In the formula, The first stiffness of the quasi-isolation system This represents the total displacement of the system below the level.

[0032] The first control point is determined as ( , ), The shear force at the pier base of the equivalent nonlinear single-degree-of-freedom (ENLSDOF) system below the level.

[0033] Preferably, the second system control point includes:

[0034] By obtaining the performance target control points under level 2, the first energy correction coefficient is obtained by the ratio of the second stiffness and the first stiffness of the quasi-isolation system, and then the total displacement of the system under level 2 is obtained.

[0035] Preferably, the ratio of the second stiffness to the first stiffness of the quasi-isolation system includes:

[0036]

[0037]

[0038] In the formula, To determine the pier stiffness under level two of the quasi-isolation system, The initial stiffness after the support and stop are connected in parallel. The initial stiffness of the bridge pier obtained according to the general ductile design method, The first stiffness ratio;

[0039] The first energy correction coefficient includes:

[0040] .

[0041] In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system.

[0042] Preferably, the total system displacement at level two includes:

[0043]

[0044] In the formula, This represents the total displacement of the system at level 2. For the base shear of the ELSDOF system at level 2, The top displacement of the ELSDOF system at level 2. For the pier foundation shear of the ENLSDOF system at level II;

[0045] Determine the control point of the second system ( , ).

[0046] Preferably, the third system control point includes:

[0047] By obtaining the performance target control points under level 2, the third stiffness and stiffness ratio of the quasi-isolation system, the energy correction coefficient is obtained, and the total displacement of the system under level 2 is obtained.

[0048] Preferably, the ratio of the third stiffness to the second stiffness of the quasi-isolation system includes:

[0049]

[0050]

[0051] In the formula, The third stiffness of the quasi-isolation system, This represents the post-yield stiffness of the pier column. The post-yield stiffness of the stop. The second stiffness ratio;

[0052] The second energy correction factor includes:

[0053] .

[0054] In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system;

[0055] The total system displacement under level three includes:

[0056]

[0057]

[0058] In the formula, For the base shear of the ENLSDOF system at level 3, For the base shear of the ELSDOF system under level 3, The displacement of the top of the ELSDOF system under level 3.

[0059] Preferably, determining whether the ductility coefficients of the bridge piers and supports meet the target performance requirements includes:

[0060] The ductility coefficients of bridge piers and supports must meet the following requirements:

[0061]

[0062]

[0063] In the formula, The support ductility coefficient, ductility coefficient of pier column For the maximum displacement of the parallel system of supports and stops, For the support yield displacement, This represents the yield displacement of the pier column. The threshold value for the ductility coefficient of the pier column. The threshold value is the support ductility coefficient.

[0064] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0065] Using the method provided by this invention, a multi-level orderly energy dissipation mechanism can be fully and sequentially implemented through the design of the aforementioned reasonable mechanical performance parameters of the steel blocks for earthquakes of different magnitudes. Different fortification mechanisms will be triggered under different earthquake magnitudes, fully utilizing the seismic isolation effect of the supports and the limiting energy dissipation capacity of the steel blocks to delay and reduce seismic damage to the piers, and effectively preventing beam collapse of the superstructure, thus achieving a multi-level orderly seismic isolation and energy dissipation mechanism. Furthermore, the steel blocks proposed in this invention will not damage the cap beams and abutment caps upon failure; the steel blocks are easy to replace and install after an earthquake; main beam displacement is easily reset; and the bridge can be restored to its usability more quickly.

[0066] The advantages of this invention are its simple structure and convenient construction. Through simple structural design, it avoids beam collapse damage and reduces maintenance costs. It can realize a multi-level orderly seismic isolation and energy dissipation mechanism. The structural system is similar to the conventional plate rubber bearing support system. It is inexpensive, simple in structure, and convenient in construction and maintenance. Compared with typical seismic isolation systems, it has a higher cost performance and a wider range of applications. It has significant advantages in the large number of highway bridges. Attached Figure Description

[0067] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0068] Figure 1 This is a schematic diagram of the process of the present invention;

[0069] Figure 2 These are schematic diagrams of level 1, level 2, and level 3 of the present invention;

[0070] Figure 3 This is a simplified two-degree-of-freedom model of the bridge according to the present invention;

[0071] Figure 4 This is the pier push-down force-displacement curve of the present invention;

[0072] Figure 5 The target spectra of level one, level two, and level three of this invention;

[0073] Figure 6 These are the performance target control points for the single-degree-of-freedom model of this invention at three levels;

[0074] Figure 7 These are the system control points at three levels of the two-degree-of-freedom model of this invention;

[0075] Figure 8 This is a bridge structure model for the present invention.

[0076] Icons: 1. Superstructure, 2. Plate rubber bearing, 3. Restraint device, 3-1. Steel beam, 3-2. Fixing bolt, 3-3. Limiting block, 3-4. Upper connecting slot, 3-5. Lower connecting slot, 4. Steel block, 5. Pad stone, 5-1. Groove, 6. Cap beam, 7. Pier. Detailed Implementation

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0078] Please refer to Figure 1 and Figure 8 As shown, a multi-stage ordered seismic construction method for bridges with lateral quasi-isolation includes:

[0079] S101: Obtain the basic design parameters of the bridge structure, set three different levels of seismic levels according to the seismic intensity, confirm the target performance of the three different levels of seismic levels, and obtain the corresponding target spectrum through the three different levels of seismic levels. The target spectrum is a force-displacement relationship curve.

[0080] Based on the seismic fortification requirements of bridge structures under earthquakes of different intensity levels, performance targets at three levels are determined, and a method for determining reasonable mechanical parameters of steel blocks is proposed to control the damage state of bridges and meet the multi-level seismic fortification requirements of quasi-isolated bridges.

[0081] This includes determining the basic components of the bridge structure, including the superstructure, plate rubber bearings, steel blocks, specific geometric parameters of the piers, and reinforcement strength.

[0082] In this example, specifically, it includes the superstructure 1, plate rubber bearing 2, restraint device 3, steel block 4, pad stone 5, cap beam 6, and pier 7.

[0083] The steel block 4 is composed of multiple slotted steel plates with strong deformation and energy dissipation capabilities; the restraint device 3 includes a steel beam 3-1, fixing bolts 3-2, limit block 3-3, upper connecting slot 3-4 and lower connecting slot 3-5. The bottom of the steel block 4 is fixed to the top surface of the bridge cap beam or abutment by the lower connecting slot 3-5, and the upper part of the steel block 4 is installed on the side of the superstructure by the upper connecting slot 3-4.

[0084] The plate rubber bearing 2 is a commonly used ordinary plate rubber bearing. The plate rubber bearing 2 is placed on the pad stone 5. The upper part of the pad stone 5 has a groove 5-1. The width of the groove 5-1 is the same as that of the plate rubber bearing 2. The lower part of the pad stone 5 is fixed to the top of the cap beam 6. The horizontal distance between the pad stones 5 is greater than the width of the horseshoe.

[0085] The superstructure 1 includes a horseshoe, with a steel plate at the bottom of the horseshoe, and the steel plate is fixed to the bottom of the horseshoe; the initial design of the bridge structure is completed according to the traditional ductility method, and the basic components of the bridge structure are determined.

[0086] Under random earthquakes of varying intensities, the superstructure 1 can undergo lateral displacement or slippage on the plate rubber bearing 2. Depending on the different sliding displacements of the superstructure 1, the plate rubber bearing 2, steel block 4, pad stone 5, and pier 7 can take turns to function, thereby achieving a three-level orderly energy dissipation mechanism.

[0087] The three different levels of earthquake levels include Level 1, Level 2 and Level 3, which have progressively higher seismic intensity.

[0088] In this embodiment, a three-level seismic isolation design requirement for bridges is proposed. Specifically, during earthquakes of relatively small magnitude (Level 1), the performance objective of the bridge system is immediate use after the earthquake (Level 10), wherein the pier structure is expected to remain resilient after the earthquake and require no maintenance.

[0089] During a moderate-level earthquake, i.e., Level II action, the system's performance objective is rapid recovery (SR stage). At this stage, the supports undergo slip isolation, the steel blocks act as fuses to dissipate seismic energy, and the pier structure maintains elasticity through capacity design.

[0090] During the maximum credible earthquake, i.e. Level 3, the system's performance objective is to avoid severe damage and collapse (CP stage) by means of support slippage to form seismic isolation and drive steel blocks to dissipate seismic energy; the proposed three-level seismic design requirements form a three-tiered seismic fortification mechanism for the bridge.

[0091] A target spectrum is established, converting the acceleration-period response spectrum curves under different seismic intensities into force-displacement relationship curves for a single-degree-of-freedom system; the vertical axis represents the base shear force, using spectral acceleration. The displacement is calculated by multiplying by the structural mass m, and the horizontal axis represents the displacement of the equivalent single-degree-of-freedom system.

[0092] S102: The bridge structure is equivalent to an equivalent linear single-degree-of-freedom system (ELSDOF) to obtain the equivalent mass. The equivalent ELSDOF curve is obtained based on the stiffness. The equivalent ELSDOF curve and the demand spectrum curve are established on the same coordinate system to obtain the performance target control points of three different seismic levels.

[0093] Three target control points were determined, and the seismic energy spectra of the structure at different seismic intensities (Level 1, Level 2, and Level 3) and the force-displacement curves of the equivalent elastic single-degree-of-freedom system were plotted on the same coordinate graph. This yielded the maximum elastic force and displacement of the elastic single-degree-of-freedom system under the three seismic intensities, which are the performance target control points at the three levels.

[0094] , ,

[0095] In the formula, , and The base shear forces of the ELSDOF system at levels one, two, and three are respectively. , and The maximum displacement of the equivalent single-degree-of-freedom system under Level 1, Level 2 and Level 3 respectively.

[0096] S103: System control points for three different seismic levels are determined by using performance target control points for three different seismic levels.

[0097] An equivalent energy balance constraint equation is established. The static demolition process corresponds to the monotonic maximum response of the structure, while the nonlinear single-degree-of-freedom model of the structure is subjected to the dynamic incremental energy during the ground motion from level one to level two. and the dynamic increment energy during ground motion from level 2 to level 3 Energy consumption is higher than that of static push-down process and When this is the case, a correction factor is usually used. , To characterize this energy relationship, we obtain

[0098]

[0099]

[0100] In the formula, The energy consumed in the process of demolishing the bridges from Level 1 to Level 2. The energy consumed in the process of demolishing bridges from level two to level three.

[0101] Based on the above energy balance relationship, mechanical equilibrium constraint equations for the structure under three levels of seismic intensity are established respectively. This allows for parameter selection and design of the structure's support constraint system, achieving performance targets at different stages.

[0102] S104: Obtain data from system control points to calculate the displacement of bridge piers and supports at three levels, thereby obtaining the ductility coefficients of the piers and supports, and determining whether the ductility coefficients of the bridge piers and supports meet the target performance requirements.

[0103] S105: If satisfied, output the result; otherwise, readjust the mechanical parameters of the selected steel block, redetermine the system control points of three different seismic levels, until the ductility coefficients of the bridge piers and bearings meet the expected target performance requirements, and output the result.

[0104] In this invention, based on the determination of the basic components of the bridge structure, the mechanical performance of the steel blocks is designed in conjunction with the equivalent energy balance equation to meet three levels of performance requirements; the proposed three-level seismic fortification requirements form a three-tiered seismic fortification mechanism for the bridge. This invention fully utilizes the sliding of the superstructure on the plate rubber bearings and rationally designs the transverse steel blocks, enabling them to function sequentially to achieve a multi-level protection mechanism for transverse seismic resistance of the bridge, controlling the residual transverse displacement of the superstructure, avoiding beam collapse damage, and delaying pier damage. The transverse steel blocks of this bridge are similar to conventional plate rubber bearing bridge systems, with simple construction, low cost, and convenient construction and maintenance. Compared with typical seismic isolation systems, they have a higher cost-performance ratio and a wider range of applications, showing significant advantages in a large number of bridges.

[0105] In this invention, the mechanical properties of the plate rubber bearing after considering frictional slippage exhibit ideal bilinearity. It is assumed that the force-displacement skeleton curve of the steel plate block is bilinear. During an earthquake, the bearing and the block are connected in parallel, and the block and the bearing jointly constrain the lateral displacement of the superstructure. They have the same lateral displacement. The stage when the block yields but the bearing does not slip is ignored, that is, it is assumed that the post-buckling stiffness of the support constraint system is equal to the post-buckling stiffness of the steel block. The parallel support constraint system can be simplified to a bilinear constitutive curve. The degradation process after severe damage to the pier is ignored, and the pier is simplified to a bilinear constitutive curve. Thus, the seismic design system is composed of the superstructure, the support constraint system and the pier, and its load-displacement relationship is trilinear.

[0106] The steel stop block is composed of multiple slotted steel plates with strong deformation and energy dissipation capabilities; the slotted steel plates have holes at both the top and bottom; multiple slotted steel plates are constrained to form a complete steel stop block; the bottom of the steel stop block is mounted on the top surface of the bridge cap beam or abutment by a lower constraining device, and the upper part of the steel stop block is fixed to the side of the superstructure by an upper constraining device; the steel stop block can be combined with multiple ribs n and multiple steel energy dissipation plates N according to design requirements, and the yield strength of the steel stop block is... and initial stiffness The following requirements must be met:

[0107] Elastic stiffness:

[0108]

[0109] Yield strength:

[0110]

[0111] In the formula, Young's modulus; The thickness of the rib; Compared to the width of the rib, , This refers to the number of steel plates. This refers to the number of ribs on a single steel plate. This refers to the height of the steel plate. The ultimate stress of the steel energy-consuming plate; The width of the rib is [value]. The width of a single steel plate is given, and the stiffness of the steel block after yielding is given. =0.03 .

[0112] The sliding phenomenon of plate rubber bearings mainly occurs between the bearing and the bottom steel plate of the beam. After the bearing slides, the main beam is in a state of "random equilibrium". It is assumed that the friction coefficient of 0.25 remains constant during the sliding process. A simplified bilinear analysis model is proposed based on the bearing sliding mechanism.

[0113]

[0114]

[0115] In the formula, The shear modulus of the bearing rubber is taken as 1200 kN / m according to the specification. 2 ; The area of ​​the support rubber plate; This represents the total thickness of the rubber layer; The axial pressure of the support, The coefficient of friction of the bearing rubber is . This is the support yield load, i.e., the sliding friction load. This represents the initial stiffness of the support.

[0116] like Figure 3 As shown, the bridge is simplified into an equivalent linear single-degree-of-freedom (ELSDOF) system. For bridges considering support slippage, the support constraint system and piers are connected in series, and its vibration characteristics are closer to a two-degree-of-freedom (TDOF) system. The blocks and supports within the support constraint system are connected in parallel. The support constraint system can be equivalently replaced by plate rubber bearings with the same mechanical properties. The TDOF system first needs to be transformed into an ELSDOF system. It is assumed that the vector of the mode shape {Ф} of the TDOF system remains unchanged during the analysis, and that the displacement shape of the TDOF system is similar to the fundamental vibration mode of the system. It is also assumed that both the ELSDOF and TDOF systems vibrate in the first mode, and that the displacement shape of the TDOF system is similar to the fundamental vibration mode of the system. Based on the ELSDOF model, the equivalent mass is given. :

[0117]

[0118] After simplifying the quasi-isolated bridge design into a TDOF system, the top displacement of the TDOF system... The relationship between the displacement Δ of the ELSDOF system and the displacement Δ is expressed in the equation:

[0119]

[0120] In the formula, It is the vector value of the first modal shape at the top of the TDOF system. represents the participation coefficient of the first mode of the ELSDOF system.

[0121] like Figure 5 As shown, in an exemplary embodiment of the present invention, the first system control point includes:

[0122] Calculate the load on the support constraint system under the target performance of level 10, and calculate the total stiffness of the steel block and the first stiffness of the quasi-isolation system;

[0123] The total displacement of the system below the level is obtained based on the equivalent single-degree-of-freedom and two-degree-of-freedom relationship, and the first system control point is determined.

[0124] Specifically, for bridges with quasi-isolation design, under level I strength, it is expected that no slippage will occur between the piers and beams, and the piers will remain elastic, achieving the performance target of I0. The fundamental period of the ELSDOF system... It is determined by the following formula.

[0125]

[0126] Based on the spectral acceleration corresponding to the fundamental period of the level-one intensity response spectrum ( , ), and From Figure 2 The intersection of the mid-level curve and the ELSDOF bearing capacity curve was identified, i.e.

[0127]

[0128] In the formula, The spectral acceleration corresponds to the fundamental period of the level-intensity response spectrum.

[0129] Specifically, the calculation of the loads on the support constraint system under the level-10 target performance includes:

[0130]

[0131] In the formula, For the load supporting the constraint system, For the quality of the bridge superstructure. For the quality of the bridge substructure. The base shear force of the ELSDOF system below level.

[0132] Preferably, the calculation of the total stiffness of the steel stop includes:

[0133]

[0134]

[0135]

[0136]

[0137] In the formula, This is the frictional force when the support begins to slide, and also the support yield load. Steel block yield load, The number of steel blocks. The yield strength of the steel stop is given by [the value of the steel stop]. The total stiffness of the steel stop block, The total stiffness of a single steel stop block;

[0138] The first stiffness of the quasi-isolation system includes:

[0139]

[0140] The total system displacement below the level includes:

[0141]

[0142] In the formula, The first stiffness of the quasi-isolation system This represents the total displacement of the system below the level.

[0143] The first control point is determined to be D( , ), The pier foundation shear force of the ENLSDOF system is at a lower level.

[0144] In one exemplary embodiment of the present invention, the second system control point includes:

[0145] By obtaining the performance target control points under level 2, the first energy correction coefficient is obtained by the ratio of the second stiffness and the first stiffness of the quasi-isolation system, and the total displacement of the system under level 2 is obtained.

[0146] At level two intensity and These are the base shear force and displacement of the ELSDOF system under level II strength, from... Figure 2 Identification of the intersection point between the leveling curve and the ELSDOF bearing capacity curve.

[0147]

[0148] In the formula, The spectral acceleration corresponds to the fundamental period of the level two intensity response spectrum.

[0149] The incremental energy of the ELSDOF system from level one to level two is :

[0150]

[0151] According to the law of conservation of energy, the incremental energy of the ENLSDOF model under ground motion from level 1 to level 2 is defined as... It also points out that the improved EEDP method will Equivalent to ,Right now:

[0152]

[0153] The energy dissipated during the monotonic derivation of the ENLSDOF model is calculated as follows:

[0154]

[0155] In the formula, The shear force at the pier foundation of the ENLSDOF system at level 2.

[0156] Since the static push-down process corresponds only to the monotonic maximum response of the structure, while an earthquake is a cyclic process, the incremental energy of the structure in the ENLSDOF model when subjected to ground motion from level one to level two is higher than the energy consumed in the static push-down process. Through the first correction factor To characterize the relationship between static and dynamic energy consumption:

[0157]

[0158] Specifically, due to the constraint of the stop, the support did not slip, the stop experienced slight yielding, and the ratio of the second stiffness to the first stiffness of the quasi-isolation system includes:

[0159]

[0160]

[0161] In the formula, The second stiffness of the quasi-isolation system The initial stiffness after the support and stop are connected in parallel. For the initial elastic stiffness of the bridge pier, This is the first stiffness ratio.

[0162] The first energy correction factor includes:

[0163] .

[0164] In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system.

[0165] in , , and This can be obtained from Table 1 below.

[0166] Table 1 Different stiffness ratios Down Fit coefficient

[0167]

[0168] Specifically, the total system displacement under level 2 includes:

[0169]

[0170] In the formula, This represents the total displacement of the system at level 2. For the base shear of the ELSDOF system at level 2, The top displacement of the ELSDOF system at level 2. The shear force at the pier foundation of the ENLSDOF system at level 2.

[0171] Determine the second system control point E( , ).

[0172] In one exemplary embodiment of the present invention, a performance target constraint equation for CP under level three earthquake is established. Under level three strength, with a performance target of CP, the quasi-isolated bridge needs to withstand earthquakes without the collapse of the piers. At this time, the piers yield and dissipate energy, the bearings of the support constraint system continue to slide to isolate the seismic force, and the steel blocks dissipate the seismic energy.

[0173] The third system control points include:

[0174] By obtaining the performance target control points under level 2, the third stiffness and stiffness ratio of the quasi-isolation system, the energy correction coefficient is obtained, and the total displacement of the system under level 2 is obtained.

[0175] The incremental energy of the ELSDOF model from level 2 to level 3 is defined as... The incremental energy of an ENLSDOF system subjected to ground motion from level 2 to level 3 is defined as Δ. E ENL3 When the ENLSDOF system is monotonically pushed from level 2 to level 3, its incremental energy is defined as... . Figure 6 Showing and ΔE e3 The relationship between the two and the expected performance of the ENLSDOF system at level three.

[0176] and These are the base shear force and top displacement of the ELSDOF system under three horizontal strength conditions, which can be obtained from... Figure 2 Identification of the intersection point between the mid-level three-reaction spectrum curve and the ELSDOF capacity curve.

[0177]

[0178] In the formula, The spectral acceleration corresponds to the fundamental period of the level two intensity response spectrum.

[0179] The incremental energy of the ELSDOF model from level 2 to level 3 is The following determination is made.

[0180]

[0181] According to the law of conservation of energy, the incremental energy of the ENLSDOF model under the influence of ground motion from level 2 to level 3 is defined as... The improved EEDP method will... Equivalent to get:

[0182]

[0183] When the ENLSDOF system is monotonically pushed from level two to level three, the incremental energy is obtained as follows: :

[0184]

[0185] Since the static push-down process corresponds only to the monotonic maximum response of the structure, and earthquakes are cyclic processes, the incremental energy of the structure in the ENLSDOF model when subjected to ground motion from level 2 to level 3 is higher than the energy consumed in the static push-down process. Through the second correction factor To characterize the relationship between static and dynamic energy consumption:

[0186]

[0187] Specifically, the ratio of the third stiffness to the second stiffness of a quasi-isolation system includes:

[0188]

[0189]

[0190] In the formula, The third stiffness of the quasi-isolation system, The stiffness of the bridge pier after yielding. The stiffness of the steel stop after yielding. The second stiffness ratio;

[0191] The second energy correction factor includes:

[0192] .

[0193] In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system;

[0194] in , , and This can be obtained from Table 2 below.

[0195] Table 2 Different stiffness ratios Down Fit coefficient

[0196]

[0197] The total displacement of the system under level 3 includes:

[0198]

[0199]

[0200] In the formula, For the base shear of the ENLSDOF system at level 3, For the base shear of the ELSDOF system under level 3, To determine the top displacement of the ELSDOF system under level 3, To obtain the total displacement of the system under level 3, the control point F of the third system is obtained. , ).

[0201] The support position is shifted to:

[0202]

[0203] In the formula, This represents the third level limit displacement of the support. This represents the total displacement at the top of the ENLSDOF system.

[0204] Preferably, determining whether the ductility coefficients of the bridge piers and supports meet the target performance requirements includes:

[0205] The ductility coefficients of bridge piers and supports must meet the following requirements:

[0206]

[0207]

[0208] In the formula, The ductility coefficient of the beam-pier column is... For the support ductility coefficient, This represents the third level limit displacement of the support. For the support yield displacement, This represents the yield displacement of the bridge pier. The threshold value for the ductility coefficient of beams and piers. The threshold value is the support ductility coefficient.

[0209] In this invention, the main workflow is as follows:

[0210] like Figure 4 As shown, the Pushover method is used to perform a lateral analysis of the bridge piers, obtaining the displacement-shear force curve of the pier cap beam center and the bridge base, thus acquiring the basic design parameters of the bridge. These include: pier mass, superstructure mass, initial stiffness of the pier column, secondary stiffness, yield load, and yield displacement. Based on the principle of normal use, the stiffness and strength of the supports are initially selected, and the support friction is determined.

[0211] Based on the seismic intensity of the bridge site as specified in the "Code for Seismic Design of Highway Bridges", the target spectra corresponding to Level 1, Level 2, and Level 3 are obtained. The target spectra are then converted into F-Δ demand spectrum curves.

[0212] like Figure 5-6 As shown, the structure is equivalent to a single-degree-of-freedom ELSDOF system according to the formula, and the equivalent mass is obtained. The fundamental period is calculated, and the equivalent ELSDOF curve is obtained based on the stiffness. The equivalent ELSDOF single-degree-of-freedom curve and the F-Δ demand spectrum curve are plotted on a coordinate system, and three performance target control points are obtained. , , .

[0213] like Figure 7 As shown, the load on the support and constraint system under the target performance of level 1IO is calculated. The total stiffness and second stiffness of the steel block and the first stiffness of the system are calculated. Based on the equivalent single-degree-of-freedom and two-degree-of-freedom relationship, the total displacement of the system below level is obtained, and the first system control point D is determined. , ).

[0214] Performance control points under level two target Calculate the system's second stiffness and stiffness ratio. Based on the period and stiffness ratio, obtain the first energy correction coefficient, and calculate the total system displacement of the ENLSDF system at level 2. Obtain the total top displacement of the two-degree-of-freedom system, and then the support displacements. Thus, determine the system control point E(…). , ).

[0215] The third stiffness of the system is calculated, and the second energy correction factor is determined based on the period and stiffness ratio. The base shear force and displacement of the ENLSDOF system under level 3 are calculated. Then, the total displacement at the top of the two-degree-of-freedom system is obtained, and consequently, the ultimate displacement of the supports is derived. The control point F(…) of the system is obtained. , ).

[0216] After obtaining the pier displacement and support displacement, check whether the ductility coefficients of the supports and piers meet the target performance requirements for no-seat collapse and moderate damage, i.e. , If the ductility coefficient is greater than the target requirement, then the parameters of the steel stop are selected again and the calculation is repeated.

[0217] This invention provides a specific calculation example to further explain and illustrate the invention.

[0218] This paper analyzes simply supported bridges in the general standard drawings of highway bridges in my country and uses a quasi-seismic isolation method to design butterfly-shaped steel plate blocks to achieve multi-level target performance.

[0219] The basic characteristics are as follows: It is a Class B highway bridge with a seismic fortification intensity of 9 degrees, a site category of Class II, and a characteristic period of... =0.45g. The superstructure consists of five 20m prestressed T-beams with a total weight of 389t per span (including the second-phase dead load). The substructure consists of double-column piers, each 10m high with a column diameter of 1.4m and a total weight of 118.5t.

[0220] 10 plate rubber bearings, total stiffness =28190kN / m. The coefficient of friction of the support is 0.25, and the frictional force is... =953kN, sliding deformation =0.034mm.

[0221] The pushover method was used to perform a lateral pushover analysis on a 10m bridge pier, obtaining the displacement-shear force curve at the center of the pier cap beam. (Bridge superstructure mass) =389t, pier mass =118.5t, initial stiffness of the pier column =46094kN / m, second stiffness =0.053 Yield load =2443kN, pier yield displacement =0.053m. The ductility coefficient thresholds for piers and supports are shown in Table 3. The design objective is for both supports and piers to suffer only minor damage. The simplified parameters for the two-free system are:

[0222] ,

[0223] Table 3 Thresholds for Ductility Coefficients of Supports and Piers

[0224]

[0225] According to the "Code for Seismic Design of Highway Bridges", the basic acceleration of a Class B bridge with a seismic intensity of 9 degrees is 0.4g. The design response spectra under Level I, Level II and Level III are obtained by amplitude adjustment. The target spectrum is converted into an F-Δ demand spectrum curve according to formulas (5)~(6).

[0226] The structure is equivalent to a single-degree-of-freedom system, and the equivalent mass of the bridge is calculated. =502t, and then calculate the equivalent fundamental period. =0.657s. Based on the pier stiffness. The equivalent ELSDOF single-degree-of-freedom curve and the F-Δ demand spectrum curve are plotted on a single coordinate system. The three intersection points of the graph provide the performance target control points at three different levels, with coordinates as follows:

[0227] =(0.032,1460);

[0228] =(0.048,2230);

[0229] =(0.055,2532).

[0230] Calculate the distributed inertial forces within the support constraint system under the target performance of Level 1I. =1118kN, yielding the buckling load of the butterfly-shaped steel plate block. = - =1118-953=165kN.

[0231] Given that the initial stiffness and yield strength of a single steel plate are respectively... =46000 kN / m, =91.2kN. Assume the total stiffness of the steel blocks within the upper support constraint system is... The number of steel blocks N is calculated according to formula (17) = / ==2, total stiffness is =2×46000 =96000kN / m, =0.03 =2760kN / m. Therefore, the yield displacement of the steel block can be obtained as... =0.009m, =120190 kN / m. Based on the equivalent single-degree-of-freedom and two-degree-of-freedom relationship, the total displacement of the system is obtained. = + =0.032 + 0.009 = 0.041m. Therefore, the system control point is obtained. =(0.041,1460).

[0232] Under the target performance of Level II SR, take the system force Equal to the yield strength of the bridge pier ,Right now = =2443kN.

[0233] calculate =30950kN / m, =18517kN / m, k= / =0.556. According to , The first correction coefficient is obtained. =0.677, calculate the pier displacement of the ENLSDOF system. =0.054m. Displacement of a two-degree-of-freedom TDOF system. and ENLSDOF displacement Relationship, calculate the total displacement of the quasi-isolation system = =0.054×1.32×1.31=0.094m, thus obtaining the support displacement. = - =0.039m. Therefore, the control point is obtained. =(0.094,2443).

[0234] Under the target performance of level 3CP, calculate the support system =1256kN, shear force of pier column =1874kN, system =1297kN / m. According to... , Determine the second energy correction factor =0.698, calculate the ultimate base shear of the ENLSDOF system. =2456kN, thus obtaining 0.064m.

[0235] Then, based on the top displacement of the two-degree-of-freedom TDOF system and ENLSDOF displacement The relationship between the two degrees of freedom is used to obtain the total displacement at the top of the system:

[0236] = =0.064×1.32×1.31=0.111m, thus obtaining the sliding displacement of the support. = - =0.047m. Therefore, we obtain... =(0.111,2447).

[0237] The ductility coefficients of the supports and piers were calculated, and both were found to be slightly damaged. Therefore, the strength of the steel blocks in the quasi-isolation system design can meet the target performance requirements at three different levels.

[0238]

[0239]

[0240] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing a multi-stage ordered seismic-resistant bridge with lateral quasi-isolation, characterized in that, include: The basic design parameters of the bridge structure are obtained, and three different levels of seismic levels are set according to the seismic intensity. The corresponding target spectrum is obtained through the three different levels of seismic levels. The target spectrum is a force-displacement relationship curve. The bridge structure is equivalent to an equivalent linear single-degree-of-freedom system (ELSDOF). The force-displacement response curve under elastic state is obtained based on the ELSDOF system. The force-displacement response curve and demand spectrum curve of the ELSDOF system are established on the same coordinate system to obtain the performance target control points of three different seismic levels. Three target control points were determined, and the seismic energy spectra of the structure at different seismic intensities and the force-displacement curves of the equivalent elastic single-degree-of-freedom system were plotted on the same coordinate graph. This yielded the maximum elastic force and displacement of the elastic single-degree-of-freedom system at the three seismic intensities, which are the performance target control points at the three levels. 、 、 In the formula, , and The base shear forces of the ELSDOF system at levels one, two, and three are respectively. , and The maximum displacement of the equivalent single-degree-of-freedom system under Level 1, Level 2 and Level 3 respectively; The system control points for the three different seismic levels were determined by using performance target control points for three different seismic levels, and the mechanical performance parameters of the steel retaining blocks were obtained. An equivalent energy balance constraint equation is established. The static demolition process corresponds to the monotonic maximum response of the structure, while the nonlinear single-degree-of-freedom model of the structure is subjected to the dynamic incremental energy during the ground motion from level one to level two. and the dynamic increment energy during ground motion from level 2 to level 3 Energy consumption is higher than that of static push-down process and When using a correction factor , To characterize the energy balance relationship, we obtain: In the formula, The energy consumed in the process of demolishing the bridges from Level 1 to Level 2. The energy consumed in the process of demolishing the bridges from Level 2 to Level 3; Based on the energy balance relationship, mechanical equilibrium constraint equations for the structure are established under three levels of seismic intensity. The displacement of bridge piers and supports at three levels is calculated by acquiring data from the system control points, thereby obtaining the ductility coefficients of the piers and supports, and determining whether the ductility coefficients of the bridge piers and supports meet the target performance requirements. If the conditions are met, the result is output. If not, the mechanical parameters of the selected steel block are readjusted, and the system control points of three different seismic levels are redefined until the ductility coefficients of the bridge piers and supports meet the expected performance requirements. The result is then output.

2. The method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 1, characterized in that, It also includes obtaining output results that meet the expected target performance requirements, and obtaining the performance status of the quasi-isolation system under different seismic levels based on the output results; The three different levels of seismic levels include Level 1, Level 2 and Level 3, which have progressively higher seismic intensity; the system control points include the first system control point, the second system control point and the third system control point. The first system control point includes: Calculate the load on the support constraint system under the target performance of level 10, calculate the total stiffness and strength of the steel block, and the first stiffness of the quasi-isolation system; The total displacement of the system below the level is obtained based on the equivalent single-degree-of-freedom and two-degree-of-freedom relationship, and the first system control point is determined.

3. The method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 2, characterized in that, The calculation of the loads supporting the constraint system under the level-10 target performance includes: In the formula, For the load supporting the constraint system, For the quality of the bridge superstructure. For the quality of the bridge substructure. The base shear force of the ELSDOF system below level.

4. The method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 3, characterized in that, The calculation of the total stiffness of the steel stop includes: In the formula, This refers to the frictional force of the bridge superstructure. The load borne by the steel stop block The number of steel blocks. The yield strength of the steel stop is given by [the value of the steel stop]. The total stiffness of the steel stop block, The total stiffness of a single steel block. For the load supporting the constraint system, The coefficient of friction of the bearing rubber; The first stiffness of the quasi-isolation system includes: The total system displacement below the level includes: In the formula, The initial stiffness of the bridge pier is obtained according to the general ductile design method. The first stiffness of the quasi-isolation system This represents the total displacement of the system below the level. The first control point is determined as ( , ), The shear force at the pier base of the equivalent nonlinear single-degree-of-freedom (ENLSDOF) system below the level.

5. The method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 4, characterized in that, The second system control point includes: By obtaining the performance target control points under level 2, the first energy correction coefficient is obtained by the ratio of the second stiffness and the first stiffness of the quasi-isolation system, and the total displacement of the system under level 2 is obtained.

6. The method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 5, characterized in that, The ratio of the second stiffness to the first stiffness of the quasi-isolation system includes: In the formula, The second stiffness of the quasi-isolation system For the parallel stiffness of all supports and steel stops, The initial stiffness of the bridge pier is obtained according to the general ductile design method. The first stiffness ratio; The first energy correction coefficient includes: In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system.

7. A method for constructing a bridge with transverse quasi-isolation multi-stage ordered seismic resistance according to claim 6, characterized in that, The total system displacement at level two includes: In the formula, This represents the total displacement of the system at level 2. For the base shear of the ELSDOF system at level 2, The top displacement of the ELSDOF system at level 2. For the pier foundation shear of the ENLSDOF system at level II; Determine the control point of the second system ( , ).

8. The method for constructing a bridge with transverse quasi-isolation multi-level ordered seismic resistance according to claim 7, characterized in that, The third system control point includes: By obtaining the performance target control points under level 2, the energy correction coefficient is obtained from the third stiffness and stiffness ratio of the quasi-isolation system, and the total displacement of the system under level 2 is obtained.

9. A method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 8, characterized in that, The third stiffness and the ratio of the second stiffness of the quasi-isolation system include: In the formula, The third stiffness of the quasi-isolation system, To determine the stiffness of the pier column after yielding. The stiffness of the steel stop after yielding. The second stiffness ratio; The second energy correction factor includes: In the formula, This is the first energy correction factor. In the first stiffness ratio The first calculated coefficient is below. First stiffness ratio The second calculation coefficient is below. First stiffness ratio The third calculation coefficient below, First stiffness ratio The fourth calculation coefficient below, The period of the ENLSDOF system; The total system displacement under level three includes: In the formula, For the base shear of the ENLSDOF system at level 3, For the base shear of the ELSDOF system under level 3, To determine the top displacement of the ELSDOF system under level 3, This represents the total displacement of the system under level three.

10. A method for constructing a bridge with transverse quasi-seismic isolation and multi-level ordered seismic resistance according to claim 8, characterized in that, The determination of whether the ductility coefficients of bridge piers and supports meet the target performance requirements includes: The ductility coefficients of bridge piers and supports must meet the following requirements: In the formula, The support ductility coefficient, The ductility coefficient of the pier column. The ultimate displacement of the parallel connection system of the quasi-isolation system blocks and supports. For the bearing yield displacement of the quasi-isolation system, The yield displacement of the pier column in the quasi-isolation system. The threshold value for the support ductility coefficient. This is the threshold value for the ductility coefficient of the bridge pier.

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