Bridge transverse quasi-seismic-isolation multistage ordered anti-seismic construction method

Abstract

The invention relates to the technical field of bridge seismic resistance, in particular to a bridge transverse quasi-seismic isolation multistage ordered seismic resistance construction method, which is used for determining performance targets under three levels according to seismic fortification requirements of a bridge structure under earthquakes with different strength levels, and providing a reasonable mechanical parameter valuing method of a steel stop block. A quasi-seismic isolation bridge multi-stage seismic fortification mechanism is established, the seismic potential of each component is exerted in sequence, the seismic damage degree of the bridge can be controlled and reduced according to an expected performance target, the phenomenon of beam falling of an upper structure of the bridge can be effectively prevented, and therefore a multi-stage ordered seismic isolation and seismic fortification mechanism is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge earthquake resistance, and in particular to a method for constructing a bridge with transverse quasi-isolation and multi-level orderly earthquake resistance. Background Art

[0002] The traditional ductile seismic design code for bridges stipulates that damage to bearings is not allowed, and that the pier column plastic hinge energy dissipation mechanism is used to resist earthquakes. However, earthquake damage such as the Wenchuan earthquake showed that the expected goals of the code were not achieved in actual earthquakes. The friction and slip of the plate rubber bearings form a natural isolation mechanism. The quasi-isolation design concept of using the sliding isolation of the bearings and the energy dissipation limit of the blocks to achieve limited plastic damage to the pier column and avoid serious damage to the bridge structure is a hot topic in existing research. As a key component to achieve this goal, the reasonable design method of the block is crucial.

[0003] At present, due to the lack of guidance from design specifications for reinforced concrete blocks, the functional positioning of existing reinforced concrete blocks in bridges is unclear and their seismic resistance is insufficient. A large number of actual earthquake damages have shown that reinforced concrete blocks, due to their high stiffness, low ductility and lack of energy dissipation capacity, will not only hinder the flexibility of plate rubber bearings under earthquake action, increase the seismic response of the lower structure, but will also lose the limiting effect on the displacement of the main beam and bearings due to brittle shear failure, resulting in the lateral seat of the main beam and even serious beam drop. This traditional reinforced concrete block cannot play an effective role in the flexible seismic isolation of plate rubber bearings and lacks sufficient deformation energy dissipation capacity. Although some elastic-plastic energy dissipation steel blocks have been proposed in existing studies, steel blocks are usually simply used in bridges to play a limiting and energy dissipation role. However, the use scenarios of steel blocks under different earthquake intensities are relatively single, and they cannot fully play their role under different random earthquake intensities. There is a lack of reasonable design methods, resulting in frequent replacement of steel blocks and low efficiency.

[0004] At present, the design calculation of the quasi-isolation system of highway bridges usually adopts nonlinear seismic response analysis based on the elastic-plastic finite element model. The parameter values ​​of the steel stoppers that meet the design objectives are generally obtained through a large number of parameter analyses. This design calculation method has two main shortcomings: 1. Elastic-plastic finite element modeling is relatively complex, and nonlinear seismic response analysis is prone to computational convergence problems; 2. The calculation workload of determining the design parameters of the steel stoppers through parameter analysis is large and time-consuming, which cannot meet the design requirements of different types of bridges and is not conducive to the application of designers in actual projects, and urgently needs to be deeply resolved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for constructing a bridge with transverse quasi-isolation and multi-level orderly earthquake-resistant structure to solve the above-mentioned problems in the prior art.

[0006] The embodiments of the present invention are implemented by the following technical solutions:

[0007] A method for constructing a bridge with transverse quasi-isolation and multi-level orderly earthquake-resistant structure, comprising:

[0008] Obtaining basic design parameters of the bridge structure, and setting three different levels of earthquake levels according to the earthquake intensity, and confirming the target performance of the three different levels of earthquake levels, and obtaining corresponding target spectra through the three different levels of earthquake levels, wherein the target spectrum is a force-displacement relationship curve;

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

[0010] The system control points of three different levels of earthquake levels are determined through the performance target control points of three different levels of earthquake levels, and the mechanical performance parameters of the steel stopper are obtained;

[0011] Obtain the data of the system control points to calculate the displacements of the bridge piers and bearings at three levels, thereby obtaining the ductility coefficients of the piers and bearings, and judging whether the ductility coefficients of the bridge piers and bearings meet the target performance requirements;

[0012] If it is satisfied, the result is output; if not, the mechanical parameters of the selected steel stopper are readjusted, and the system control points of three different levels of earthquake levels are re-determined until the ductility coefficient of the bridge pier and the ductility coefficient of the bearing meet the expected target performance requirements, and the result is output.

[0013] Preferably, the method further includes obtaining an output result that meets the expected target performance requirements, adjusting the mechanical parameters of the steel stopper according to the output result and the target performance of the current earthquake levels of different levels, obtaining the required bridge damage state, and determining whether the mechanical parameters of the steel stopper need to be readjusted according to the bridge damage state;

[0014] The three different levels of earthquake levels include level one, level two and level three with increasing earthquake intensity, and the system control points include a first system control point, a second system control point and a third system control point;

[0015] The first system control point includes:

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

[0017] According to the relationship between the equivalent single degree of freedom and double degree of freedom, the total displacement of the system below the level is obtained, and the first system control point is determined.

[0018] Preferably, the calculation of the load of the support restraint system under the level-10 target performance comprises:

[0019]

[0020] In the formula, F bdy is the yield load of the parallel system of the block and the support, m1 is the mass of the bridge superstructure, m2 is the mass of the bridge substructure, and F e1 is the base shear force of the ELSDOF system at the horizontal level.

[0021] Preferably, according to the initial performance of the support, calculating the total stiffness of the steel stopper comprises:

[0022] F by =μm1g

[0023] F dy =F bdy -F by

[0024] N=F dy / F d1

[0025] K d =NK d1

[0026] In the formula, F by is the friction force of the bridge superstructure, F dy The load borne by the steel stopper, N is the number of steel stoppers, F d1 is the yield strength of the single-piece steel stopper, K d is the total stiffness of the steel stopper, K d1 is the stiffness of the single-piece steel stop;

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

[0028] K sy =K p

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

[0030]

[0031] In the formula, K sy is the first stiffness of the quasi-isolation system, Δ y is the total displacement of the system at the level below;

[0032] Determine the first control point as (F y, Δ y ), F y To level the pier base shear force of the ENLSDOF system.

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

[0034] The performance target control point under level 2 and the ratio of the second stiffness to the first stiffness of the quasi-isolation system are obtained to obtain the first energy correction coefficient, 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-seismic isolation system comprises:

[0036]

[0037] In the formula, K sp is the column stiffness of the quasi-isolation system at level 2, K bd is the initial stiffness of the support and the block in parallel, K p is the initial stiffness of the bridge pier obtained according to the general ductility design method, k1 is the first stiffness ratio;

[0038] The first energy correction coefficient includes:

[0039]

[0040] In the formula, γ a is the first energy correction coefficient, a1 is the first calculation coefficient under the first stiffness ratio k1, b1 is the second calculation coefficient under the first stiffness ratio k1, c1 is the third calculation coefficient under the first stiffness ratio k1, d1 is the fourth calculation coefficient under the first stiffness ratio k1, and T is the period of the ENLSDOF system.

[0041] Preferably, the total displacement of the system under the second level includes:

[0042]

[0043] In the formula, Δ p is the total displacement of the system under level 2, F e2 is the base shear force of the ELSDOF system under level 2, Δ e2 is the top displacement of the ELSDOF system under level 2, F p is the pier base shear force of the ENLSDOF system under level 2;

[0044] Determine the second system control point (F p , Δ p ).

[0045] Preferably, the third system control point includes:

[0046] The performance target control point under level 2, the third stiffness and stiffness ratio of the quasi-isolation system are obtained to obtain the energy correction coefficient, and the total displacement of the system under level 2 is obtained.

[0047] Preferably, the ratio of the third stiffness to the second stiffness of the quasi-seismic isolation system comprises:

[0048]

[0049] In the formula, K su is the third stiffness of the quasi-isolation system, K p2 is the post-yield stiffness of the pier column, K d2 is the post-yield stiffness of the stopper, k2 is the second stiffness ratio;

[0050] The second energy correction factor includes:

[0051]

[0052] In the formula, γ a is the first energy correction coefficient, a2 is the first calculation coefficient under the first stiffness ratio k2, b2 is the second calculation coefficient under the first stiffness ratio k2, c2 is the third calculation coefficient under the first stiffness ratio k2, d2 is the fourth calculation coefficient under the first stiffness ratio K2, and T is the period of the ENLSDOF system;

[0053] The total displacement of the system under the level 3 includes:

[0054]

[0055] In the formula, F u is the base shear force of the ENLSDOF system at level 3, F e3 is the base shear force of the ELSDOF system under level 3, Δ e3 is the top displacement of the ELSDOF system at level three.

[0056] Preferably, the step of judging whether the ductility coefficient of the bridge pier column and the ductility coefficient of the bearing meet the target performance requirements comprises:

[0057] The ductility coefficient of bridge piers and bearings must meet the following requirements:

[0058]

[0059] In the formula, μ b is the support ductility coefficient, μ p Pier ductility factor, Δ bdu is the maximum displacement of the support and stopper parallel system, Δ by is the yield displacement of the support, Δ py is the yield displacement of the pier column, [μ b] is the threshold value of ductility coefficient of pier column, [μ p ] is the support ductility coefficient threshold.

[0060] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0061] By adopting the method provided by the present invention, the above-mentioned reasonable mechanical performance parameters of the steel block are designed for earthquakes of different levels, and the multi-level orderly energy dissipation mechanism can fully play its role in sequence. Different defense mechanisms will be triggered under earthquakes of different levels, which can fully utilize the seismic isolation effect of the support and the limiting energy dissipation capacity of the steel block to delay and reduce the seismic damage of the bridge pier, and effectively prevent the upper structure from falling beams, thereby realizing a multi-level orderly seismic isolation energy dissipation mechanism. At the same time, the steel block proposed by the present invention will not cause damage to the cap beam and the platform cap when it is destroyed. The steel block is easy to be replaced and installed after the earthquake, and the displacement of the main beam is easy to be reset, so that the bridge can easily resume its use function faster.

[0062] The advantages of the present invention are simple structure and convenient construction. Through simple structural design, it can avoid damage caused by falling beams, reduce maintenance costs, and realize a multi-level orderly seismic isolation and energy consumption mechanism. The structural system is similar to the conventional plate rubber bearing support system, with low cost, simple structure, convenient construction and maintenance. Compared with the typical isolation system, it has a higher cost performance and a wider range of applications. It has significant advantages in large-scale and wide-ranging highway bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0064] Figure 1 It is a schematic diagram of the process of the present invention;

[0065] Figure 2 It is a schematic diagram of level 1, level 2 and level 3 of the present invention;

[0066] Figure 3 It is a simplified model of the bridge with two degrees of freedom according to the present invention;

[0067] Figure 4 is the bridge pier push-down force-displacement curve of the present invention;

[0068] Figure 5 The target spectra of level 1, level 2 and level 3 of the present invention;

[0069] Figure 6are the performance target control points at three levels of the single degree of freedom model of the present invention;

[0070] Figure 7 are system control points at three levels of the dual-degree-of-freedom model of the present invention;

[0071] Figure 8 This is the bridge structure model of the present invention.

[0072] Icons: 1 superstructure, 2 plate rubber bearing, 3 restraint device, 3-1 steel beam, 3-2 fixing bolt, 3-3 limit 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 DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0074] Please refer to Figure 1 and Figure 8 As shown, a method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake-resistant structure includes:

[0075] S101: acquiring basic design parameters of the bridge structure, and setting three different levels of earthquake levels according to the earthquake intensity, and confirming the target performance of the three different levels of earthquake levels, and obtaining corresponding target spectra through the three different levels of earthquake levels, wherein the target spectrum is a force-displacement relationship curve;

[0076] According to the seismic fortification requirements of bridge structures under earthquakes of different intensity levels, the performance targets under three levels are determined, and a method for selecting reasonable mechanical parameters of steel blocks is proposed to control the damage state of the bridge and meet the requirements for realizing multi-level seismic fortification of quasi-isolation bridges.

[0077] Among them, the basic components of the bridge structure are determined, including the superstructure, plate rubber bearings, steel blocks, specific geometric parameters of the piers, reinforcement strength, etc.

[0078] In this example, specifically, it includes a superstructure 1, a plate rubber bearing 2, a restraining device 3, a steel block 4, a cushion stone 5, a cap beam 6, and a bridge pier 7.

[0079] The steel stopper 4 is composed of a plurality of seam-shaped steel plates with strong deformation and energy dissipation capabilities; the restraining device 3 includes a steel crossbeam 3-1, a fixing bolt 3-2, a limit stopper 3-3, an upper connecting slot 3-4 and a lower connecting slot 3-5. The bottom of the steel stopper 4 is fixed to the top surface of the bridge cap beam or the abutment by the lower connecting slot 3-5, and the upper part of the steel stopper 4 is installed on the side of the upper structure by the upper connecting slot 3-4;

[0080] The plate rubber bearing 2 is a commonly used ordinary plate rubber bearing. The plate rubber bearing 2 is placed on a 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 on the top of the cap beam 6. The horizontal spacing between the pad stones 5 is greater than the width of the horseshoe.

[0081] 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 to determine the basic components of the bridge structure.

[0082] Under random earthquake intensities of different levels, the superstructure 1 may undergo lateral displacement or slip on the plate rubber bearing 2. According to the different sliding displacements of the superstructure 1, the plate rubber bearing 2, the steel stopper 4, the cushion stone 5 and the bridge pier 7 may play a role in sequence, thereby realizing a three-level orderly energy dissipation mechanism.

[0083] Among them, the three different levels of earthquake levels include Level 1, Level 2 and Level 3 with increasing earthquake intensity.

[0084] In this embodiment, a third-level quasi-isolation fortification requirement for bridges is proposed. Specifically, during a relatively small earthquake, i.e., level one, the performance target of the bridge system is immediate post-earthquake use (IO stage), wherein the pier structure is expected to remain elastic after the earthquake and requires no maintenance.

[0085] During moderate-level earthquakes, i.e., level II action, the system performance goal is rapid recovery (SR stage), when the bearings undergo sliding isolation, the steel stops act as fuses to dissipate seismic energy, and the pier structure remains elastic through capacity design.

[0086] During the maximum credible earthquake, i.e., level three, the system's performance goal is to avoid serious damage and collapse (CP stage) by forming seismic isolation through bearing sliding and driving steel blocks to dissipate seismic energy; the proposed three-level fortification requirements form three seismic fortification mechanisms for the bridge.

[0087] Establish the target spectrum and convert the acceleration-period response spectrum curve under different earthquake intensities into the force-displacement relationship curve of the single degree of freedom system; the vertical axis represents the base shear force, and the spectral acceleration S is used a It is calculated by multiplying it by the structural mass m, and the horizontal axis represents the equivalent single-degree-of-freedom system displacement.

[0088] S102: Equivalent the bridge structure to an ELSDOF single degree of freedom system to obtain the equivalent mass, obtain the equivalent ELSDOF curve based on the stiffness, establish the equivalent ELSDOF curve and the demand spectrum curve in the same coordinate system, and obtain the performance target control points for three different levels of earthquake levels;

[0089] Determine the target control points under three levels, plot the seismic energy spectra of the structure at different seismic intensities (level 1, level 2 and level 3) and the force-displacement curve of the structural equivalent elastic single-degree-of-freedom system on the same coordinate graph, and obtain the maximum elastic force and displacement of the elastic single-degree-of-freedom system under the three seismic intensities, that is, the performance target control points of the three levels, namely:

[0090] A(F e1 ,Δ e1 )、B(F e2 ,Δ e2 )、C(F e3 ,Δ e3 )

[0091] In the formula, F e1 、F e2 and F e3 are the base shear forces of the ELSDOF system at levels 1, 2, and 3, respectively, Δ e1 , Δ e2 and Δ e3 The maximum displacement of the equivalent single-degree-of-freedom system at levels 1, 2, and 3 respectively.

[0092] S103: determining system control points of three different levels of earthquake levels respectively through the performance target control points of three different levels of earthquake levels;

[0093] The equivalent energy balance constraint equation is established. The static push-down process corresponds to the monotonic maximum response of the structure, and the dynamic incremental energy E of the nonlinear single-degree-of-freedom model of the structure when it is subjected to ground motion from level 1 to level 2 is e2 and the incremental energy ΔE from level 2 to level 3 ground motion e3 Higher than the energy consumption of static push-down process ΔE p and ΔE u When , correction coefficients γa and γb are usually used to characterize this energy relationship, and we can get

[0094] ΔE p =γ a ΔE e2

[0095] ΔE u =γ b ΔE e3

[0096] Where ΔE p The energy consumption during the demolition process of the bridge from level 1 to level 2, ΔE u The demolition process of bridges from Level II to Level III consumes energy.

[0097] Through the above energy balance relationship, the mechanical equilibrium constraint equations of the structure under three levels of seismic intensities are established respectively, so that the parameters of the support constraint system of the structure can be selected and designed to achieve the performance goals at different stages.

[0098] S104: Obtaining data of system control points to calculate the displacements of bridge piers and bearings at three levels, thereby obtaining ductility coefficients of the piers and bearings, and determining whether the ductility coefficients of the bridge piers and bearings meet target performance requirements;

[0099] S105: If the conditions are met, the result is output; if not, the mechanical parameters of the selected steel stopper are readjusted, and the system control points of three different levels of earthquake levels are re-determined until the ductility coefficient of the bridge pier and the ductility coefficient of the bearing meet the expected target performance requirements, and the result is output.

[0100] In the present invention, on the basis of determining the basic components of the bridge structure, the mechanical properties of the steel blocks are designed in combination with the equivalent energy balance equation to meet three levels of performance requirements; the proposed three-level defense requirements form three seismic defense mechanisms of the bridge. The present invention makes full use of the sliding of the superstructure on the plate rubber bearings, and rationally designs the transverse steel blocks so that they play a role in sequence to realize a multi-level protection mechanism for the transverse seismic resistance of the bridge, control the lateral residual displacement of the superstructure, avoid beam drop damage, and delay pier damage; the transverse steel blocks of this bridge are similar to conventional plate rubber bearing bridge systems, with simple structure, low cost, easy construction and maintenance, and higher cost-effectiveness compared to typical seismic isolation systems, and a wider range of applications, with significant advantages in large-scale and wide-ranging bridges.

[0101] In the present invention, the mechanical properties of the plate rubber bearing after friction slip are considered to be ideal bilinear, and the force-displacement skeleton curve of the steel plate block is assumed to be bilinear; in an earthquake, the bearing and the block are in a parallel relationship, and the block and the bearing jointly constrain the lateral displacement of the upper structure, and the two have the same lateral displacement, ignoring the stage after the block yields but the bearing does not slip, that is, assuming that the post-bearing stiffness of the support constraint system is equal to the post-bearing stiffness of the steel block, the parallel support constraint system can be simplified to a bilinear constitutive curve; ignoring the degradation process after the pier column is severely damaged, the bridge pier is simplified to a bilinear constitutive; thus, the defense system is composed of the upper structure, the support constraint system and the bridge pier, and its load-displacement relationship is trilinear;

[0102] The steel stopper is composed of multiple seam-shaped steel plates with strong deformation and energy dissipation capabilities; the upper and lower ends of the seam-shaped steel plates are provided with holes; multiple seam-shaped steel plates form a complete steel stopper through a restraining device; the bottom of the steel stopper is installed on the top surface of the bridge cap beam or abutment by the lower restraining device, and the upper part of the steel stopper is fixed on the side of the upper structure by the upper restraining device; the steel stopper 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 stopper is Q yd and initial stiffness K d Meet the following requirements:

[0103] Elastic stiffness:

[0104]

[0105] Yield Strength:

[0106]

[0107] Where, E is Young's modulus; t is the rib thickness; λ is the ratio of the rib width to the plate width. N is the number of steel plates; n is the number of ribs in a single steel plate; h is the height of the steel plate; σ y is the ultimate stress of the steel energy-absorbing plate; b1 is the width of the rib plate, b2 is the width of the single steel plate, and the stiffness of the steel stopper after yielding is K d2 =0.03K d .

[0108] The sliding phenomenon of the plate rubber bearing mainly occurs between the bearing and the steel plate at the bottom of the beam. After the bearing slides, the main beam is in a "random equilibrium" state; it is assumed that the friction coefficient of 0.25 remains unchanged during the sliding process. A simplified bilinear analysis model is proposed based on the bearing sliding mechanism;

[0109]

[0110] F by =μN

[0111] In the formula, G b is the shear modulus of the bearing rubber, which is 1200kN / m according to the specification 2 ; A b is the area of ​​the support rubber plate; t e is the total thickness of the rubber layer; N is the axial pressure of the bearing, μ is the friction coefficient of the bearing rubber, F by is the bearing yield load, i.e. the sliding friction load, K b is the initial stiffness of the support.

[0112] like Figure 3As shown, the bridge is simplified to an equivalent single degree of freedom system (ELSDOF). For bridges that consider bearing slip, the support constraint system and the pier are in series, and its vibration characteristics are closer to a dual degree of freedom system (TDOF). The internal block and the bearing of the support constraint system are in parallel. The support constraint system can be replaced by a plate rubber bearing with the same mechanical properties. The TDOF system first needs to be transformed into an ELSDOF. It is assumed that the vector of the vibration mode {Ф} of the TDOF system remains unchanged during the analysis process, and the displacement shape of the TDOF system is similar to the basic vibration mode of the system. It is assumed that both the ELSDOF and TDOF systems vibrate in the first mode, and the displacement shape of the TDOF system is similar to the basic vibration mode of the system. Based on the ELSDOF model, the equivalent mass M is given. eq :

[0113]

[0114] After simplifying the quasi-isolation design bridge into a TDOF system, the relationship between the top displacement δ of the TDOF system and the displacement Δ of the ELSDOF system is expressed in the equation:

[0115] δ=ΔΓ1Φ 12

[0116] In the formula, Φ 12 is the vector value of the first mode shape at the top of the TDOF system, and Γ1 is the participation coefficient of the first mode of the equivalent SDOF system.

[0117] like Figure 5 As shown, in an exemplary embodiment of the present invention, the first system control point includes:

[0118] Calculate the load of the support and restraint system under the level 10 target performance, calculate the total stiffness of the steel stopper and the first stiffness of the quasi-isolation system;

[0119] According to the relationship between the equivalent single degree of freedom and double degree of freedom, the total displacement of the system below the level is obtained, and the first system control point is determined.

[0120] Specifically, for a bridge designed for quasi-isolation, no sliding is expected between the piers and beams at level one strength, and the piers remain elastic, achieving the IO performance target. The fundamental period T0 of the ELSDOF system is determined by the following equation.

[0121]

[0122] According to the spectrum acceleration (S a ,T0),F e1 and Δ e1 Can be obtained from Figure 2The intersection of the mid-level curve and the ELSDOF bearing capacity curve is identified, that is,

[0123]

[0124] In the formula, is the spectral acceleration corresponding to the basic period of the level one intensity response spectrum.

[0125] Specifically, the calculation of the load of the support constraint system under the level-10 target performance includes:

[0126]

[0127] In the formula, F bdy is the load of the supporting restraint system, m1 is the mass of the bridge superstructure, m2 is the mass of the bridge substructure, and F e1 is the base shear force of the ELSDOF system at the horizontal level.

[0128] Preferably, the calculation of the total stiffness of the steel stopper includes:

[0129] F by =μm2g

[0130] F dy =F bdy -F by

[0131] N=F dy / F d1

[0132] K d =NK d1

[0133] In the formula, F by is the friction force when the support starts to slide, which is also the yield load of the support, F dy Steel stopper yield load, N is the number of steel stops, F d1 is the yield strength of the steel stopper, K d is the total stiffness of the steel stopper, K d1 is the total stiffness of the single-piece steel stopper;

[0134] The first stiffness of the quasi-seismic isolation system includes:

[0135] K sy =K p

[0136] The total displacement of the system below the level includes:

[0137]

[0138] In the formula, K syis the first stiffness of the quasi-isolation system, Δ y is the total displacement of the system at the level below;

[0139] Determine the first control point as D(F y , Δ y ), F y To level the pier base shear force of the ENLSDOF system.

[0140] In an exemplary embodiment of the present invention, the second system control point includes:

[0141] The performance target control point under level 2 is obtained, the second stiffness and the first stiffness ratio of the quasi-isolation system are used to obtain the first energy correction coefficient, and the total displacement of the system under level 2 is obtained.

[0142] At level 2 intensity, F e2 and Δ e2 are the base shear force and displacement of the ELSDOF system under the second strength level. Figure 2 Identify the intersection of the second level curve and the ELSDOF bearing capacity curve.

[0143]

[0144] In the formula, is the spectral acceleration corresponding to the basic period of the level 2 intensity response spectrum.

[0145] The incremental energy of the ELSDOF system from level 1 to level 2 is ΔE e2 :

[0146]

[0147] According to the law of energy conservation, the incremental energy of the ENLSDOF model when subjected to ground motion from level 1 to level 2 is defined as ΔE ENL2 , and pointed out that the improved EEDP method will ΔE e2 Equivalent to ΔE ENL2 ,Right now:

[0148] ΔE ENL2 =ΔE e2

[0149] The energy dissipated in the monotonic push-down process of the ENLSDOF model is calculated as follows:

[0150]

[0151] In the formula, F p is the pier base shear force of the ENLSDOF system under level 2.

[0152] Since the static push-down process only corresponds to the monotonic maximum response of the structure, and earthquake is a cyclic process, the incremental energy of the structural ENLSDOF model when subjected to ground motion from level 1 to level 2 is higher than the energy consumed in the static push-down process ΔE p . Through the first correction coefficient γ a To characterize the relationship between static and dynamic energy consumption:

[0153] ΔE e2 =ΔE NEL2 =γ a ΔE p

[0154] Specifically, due to the constraint of the stopper, the support does not slip, the stopper yields slightly, and the second stiffness and first stiffness ratio of the quasi-isolation system include:

[0155]

[0156] In the formula, K sp is the second stiffness of the quasi-isolation system, K bd is the initial stiffness of the support and the block in parallel, K p is the initial elastic stiffness of the pier, and k1 is the first stiffness ratio.

[0157] The first energy correction factor includes:

[0158]

[0159] In the formula, γ a is the first energy correction coefficient, a1 is the first calculation coefficient under the first stiffness ratio k1, b1 is the second calculation coefficient under the first stiffness ratio k1, c1 is the third calculation coefficient under the first stiffness ratio k1, d1 is the fourth calculation coefficient under the first stiffness ratio k1, and T is the period of the ENLSDOF system.

[0160] Wherein a1, b1, c1 and d1 can be obtained from the following Table 1.

[0161] Table 1 γ under different stiffness ratios k1 a The fitting coefficient of

[0162]

[0163] Specifically, the total displacement of the system under level 2 includes:

[0164]

[0165] In the formula, Δ p is the total displacement of the system under level 2, F e2 is the base shear force of the ELSDOF system under level 2, Δ e2is the top displacement of the ELSDOF system under level 2, F p is the pier base shear force of the ENLSDOF system under level 2.

[0166] Determine the second system control point E(F p , Δ p ).

[0167] An exemplary implementation of the present invention establishes a CP performance target constraint equation under level three earthquakes; under level three strength, performance target three CP, the quasi-isolation bridge needs to withstand the earthquake without the collapse of the bridge piers. At this time, the bridge 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.

[0168] The third system control points include:

[0169] The performance target control point under level 2, the third stiffness and stiffness ratio of the quasi-isolation system are obtained to obtain the energy correction coefficient, and the total displacement of the system under level 2 is obtained.

[0170] The incremental energy of the ELSDOF model from level 2 to level 3 is defined as ΔE e3 The incremental energy of the ENLSDOF system when it is subjected to ground motion from level 2 to level 3 is defined as ΔE ENL3 When the ENLSDOF system is pushed monotonically from level 2 to level 3, its incremental energy is defined as ΔE u . Figure 6 Shows ΔE u and ΔE e3 and the expected performance of the ENLSDOF system at level three.

[0171] F e3 and Δ e3 They are the base shear force and top displacement of the ELSDOF system under level 3 strength, which can be obtained from Figure 2 Identification of the intersection of the mid-level three-response spectrum curve and the ELSDOF capacity curve.

[0172]

[0173] In the formula, is the spectral acceleration corresponding to the basic period of the level 2 intensity response spectrum.

[0174] The incremental energy of the ELSDOF model from level 2 to level 3 is ΔE e3 ,as follows.

[0175]

[0176] According to the law of energy conservation, the incremental energy of the ENLSDOF model when subjected to ground motion from level 2 to level 3 is defined as ΔE ENL3 . Using the improved EEDP method, ΔE e3 Equivalent to ΔE ENL3 get:

[0177] ΔE ENL3 =ΔE e3

[0178] When the ENLSDOF system is monotonically pushed down from level 2 to level 3, the incremental energy is ΔE u :

[0179]

[0180] Since the static push-down process only corresponds to the monotonic maximum response of the structure, and earthquake is a cyclic process, the incremental energy of the structural 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 ΔE u Through the second correction factor γ b To characterize the relationship between static and dynamic energy consumption:

[0181] ΔE e3 =ΔE ENL3 =γ b ΔE u

[0182] Specifically, the ratio of the third stiffness to the second stiffness of the quasi-isolation system includes:

[0183]

[0184] In the formula, K su is the third stiffness of the quasi-isolation system, K p2 is the stiffness of the pier after yielding, K d2 is the stiffness of the steel stopper after yielding, k2 is the second stiffness ratio;

[0185] The second energy correction factor includes:

[0186]

[0187] In the formula, γ a is the first energy correction coefficient, a2 is the first calculation coefficient under the first stiffness ratio k2, b2 is the second calculation coefficient under the first stiffness ratio k2, c2 is the third calculation coefficient under the first stiffness ratio k2, d2 is the fourth calculation coefficient under the first stiffness ratio k2, and T is the period of the ENLSDOF system;

[0188] Wherein a2, b2, c2 and d2 can be obtained from the following Table 2.

[0189] Table 2 γ under different stiffness ratios k2 b The fitting coefficient of

[0190]

[0191] The total displacement of the system under level 3 includes:

[0192]

[0193] In the formula, F u is the base shear force of the ENLSDOF system at level 3, F e3 is the base shear force of the ELSDOF system under level 3, Δ e3 is the top displacement of the ELSDOF system at level 3, Δ u is the total displacement of the system under level 3, and the third system control point F(F u , Δ u ).

[0194] The support displacement is:

[0195] Δ bdu =δ u -Δ u

[0196] In the formula, Δ bdu is the third level limit displacement of the support, δ u is the total displacement of the top of the ENLSDOF system.

[0197] Preferably, the step of judging whether the ductility coefficient of the bridge pier column and the ductility coefficient of the bearing meet the target performance requirements comprises:

[0198] The ductility coefficient of bridge piers and bearings must meet the following requirements:

[0199]

[0200] In the formula, μ b is the ductility coefficient of beam pier and column, μ p is the support ductility coefficient, Δ bdu is the third level limit displacement of the support, Δ by is the yield displacement of the support, Δ py is the yield displacement of the bridge pier, [μ b ] is the threshold value of beam-pier-column ductility coefficient, [μ p ] is the support ductility coefficient threshold.

[0201] In the present invention, the main workflow is:

[0202] like Figure 4As shown in the figure, the Pushover method is used to analyze the piers in the horizontal direction, and the center displacement of the pier cap beam-the shear force curve of the pier bottom is obtained, and the basic design parameters of the bridge are obtained. Including: pier mass, superstructure mass, pier column initial stiffness, secondary stiffness, yield load, and yield displacement. According to the principle of normal use, the stiffness and strength of the bearing are initially selected, and the bearing friction is determined.

[0203] According to the seismic intensity of the bridge site in the "Highway Bridge Seismic Design Code", the target spectra corresponding to Level 1, Level 2 and Level 3 are obtained. The target spectrum is converted into an F-Δ demand spectrum curve.

[0204] like Figure 5-6 As shown, according to the formula, the structure is equivalent to a single degree of freedom system ELSDOF to obtain the equivalent mass. The basic period is calculated, and the equivalent ELSDOF curve is obtained according to the stiffness. The equivalent ELSDOF single degree of freedom curve and the F-Δ demand spectrum curve are plotted in a coordinate system to obtain three performance target control points, namely A(F e1 ,Δ e1 )、B(F e2 ,Δ e2 )、C(F e3 ,Δ e3 ).

[0205] like Figure 7 As shown, the load of the support constraint system under the target performance of level 10 is calculated, and the total stiffness of the steel block and the second stiffness and the first stiffness of the system are calculated. According to the relationship between the equivalent single degree of freedom and the double degree of freedom, the total displacement of the system under level 1 is obtained, and the first system control point D(F y , Δ y ).

[0206] Performance control point B (F e2 ,Δ e2 ). Calculate the second stiffness and stiffness ratio of the system. According to the period and stiffness ratio, the first energy correction coefficient is obtained, and the total displacement of the ENLSDOF system under level 2 is calculated. The total position of the top of the dual-degree-of-freedom system is obtained, and then the displacement of the support is obtained. Thus, the system control point E(F p , Δ p ).

[0207] Calculate the third stiffness of the system, and determine the second energy correction factor based on the period and stiffness ratio. Calculate the base shear force and displacement of the ENLSDOF system under level 3. Then, obtain the total displacement of the top of the two-degree-of-freedom system, and then obtain the ultimate displacement of the support. Get the system control point F(F u , Δ u ).

[0208] After obtaining the displacement of the pier column and the bearing, check whether the ductility coefficient of the bearing and the pier meets the target performance requirements of no seating and moderate damage, that is, μ b , μ p If the ductility factor is greater than the target requirement, select the parameters of the steel stopper again and recalculate.

[0209] The present invention provides a specific calculation example to further explain the present invention.

[0210] The simply supported bridges in the general standard drawings of highway bridges in my country are analyzed, and the butterfly steel plate stoppers are designed using the quasi-seismic isolation method to achieve multi-level target performance.

[0211] The basic situation is: highway bridge type B bridge, seismic fortification intensity is 9 degrees, site category II, characteristic period T g =0.45g. The upper structure consists of five 20m prestressed T-beam structures, with a total weight of 389t per span (including the second-phase dead load). The lower structure consists of double piers, with a pier height of 10m, a pier diameter of 1.4m, and a total weight of 118.5t.

[0212] 10 plate rubber bearings, total stiffness K b =28190kN / m. The friction coefficient of the support is 0.25, and the friction force is F by =953kN, sliding deformation Δ by =0.034mm.

[0213] The Pushover method is used to analyze the 10m bridge pier horizontally, and the center displacement of the bridge pier cap beam-the shear force curve of the pier bottom is obtained. The mass of the bridge superstructure m1 = 389t, the mass of the pier m2 = 118.5t, and the initial stiffness of the pier column K p =46094kN / m, second stiffness K p2 =0.053K p , yield load F py =2443kN, pier yield displacement δ py =0.053m. The ductility coefficient thresholds of piers and bearings are shown in Table 3. The design goal is that both bearings and piers are slightly damaged. The simplified double-freedom system parameters are:

[0214]

[0215] Table 3 Ductility factor thresholds for bearings and piers

[0216]

[0217] According to the Code for Seismic Design of Highway Bridges, the basic acceleration of Class B bridges with a design intensity of 9 degrees is 0.4g, and the amplitude modulation is used to obtain the design response spectra under Levels 1, 2, and 3. The target spectrum is converted into the F-Δ demand spectrum curve according to formulas (5) to (6).

[0218] The structure is equivalent to a single degree of freedom system and the equivalent mass M of the bridge is calculated. eq =502t, and then calculate the equivalent basic period T0 = 0.657s. According to the pier stiffness K p The equivalent ELSDOF single degree of freedom curve and the F-Δ demand spectrum curve are plotted in a coordinate system. From the three intersection points on the graph, the performance target control points at three levels can be obtained, and the coordinates are:

[0219] A(F e1 ,Δ e1 )=(0.032,1460);

[0220] B(F e2 ,Δ e2 )=(0.048,2230);

[0221] C(F e3 ,Δ e3 )=(0.055,2532).

[0222] Calculate the inertia force F distributed in the support constraint system under the target performance level IO bd = 1118 kN, and the buckling load F of the butterfly steel plate block is obtained dy =F bd -F by =1118-953=165kN.

[0223] It is known that the initial stiffness and yield strength of a single steel plate are K d1 =46000kN / m, F dy1 =91.2kN. Assume that the total stiffness of the steel block in the upper support restraint system is K d According to formula (17), the number of steel stoppers is calculated to be N = F dy / F dy1 = = 2, the total stiffness is K d =2×46000=96000kN / m, K d2 =0.03K d =2760kN / m. From this, we can get the yield displacement of the steel stopper as Δ bdy =0.009m, K bd =120190kN / m. According to the relationship between equivalent single degree of freedom and double degree of freedom, the total displacement of the system is obtained y =Δ y0 +Δbdy =0.032+0.009=0.041m. Thus, we get the system control point D(F y ,Δ y )=(0.041,1460).

[0224] Under the target performance of level 2 SR, take the system force F p Equal to the yield strength of the bridge pier F py , that is, F p =F py =2443kN.

[0225] Calculate K bd =30950kN / m, K sp =18517 kN / m, k = K sp / K sy =0.556. According to T0 and k2, we get the first correction coefficient γ a =0.677, calculate the pier displacement Δ of the ENLSDOF system p =0.054m. Displacement of the dual-degree-of-freedom TDOF system δ p and ENLSDOF displacement Δ p Relationship, calculate the total displacement δ of the quasi-isolation system p =Δ p Γ1Φ 12 =0.054×1.32×1.31=0.094m, and the support displacement Δ bdy =δ p -Δ p =0.039m. Thus we get the control point E(F p ,Δ p )=(0.094,2443).

[0226] Under the three-CP target performance level, calculate the support system K bd =1256kN, pier shear force F py =1874kN, system K su =1297 kN / m. Determine the second energy correction factor γ based on T0 and k2 b =0.698, calculate the ultimate base shear force F of the ENLSDOF system u =2456kN, we get Δ u =0.064m.

[0227] Then, according to the top displacement δ of the two-degree-of-freedom TDOF system u and ENLSDOF displacement Δ u The relationship between and gives the total displacement of the top of the two-DOF system:

[0228] δ u=Δ p Γ1Φ 12 =0.064×1.32×1.31=0.111m, thus obtaining the sliding displacement Δ of the support bdy =δ u -Δ u =0.047m. Thus, we can obtain F(F u ,Δ u )=(0.111,2447).

[0229] The ductility coefficients of the bearings and piers are calculated, and both the bearings and piers are slightly damaged. Therefore, the strength of the steel stopper designed for the quasi-isolation system can achieve the target performance requirements under three levels.

[0230]

[0231] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance, characterized in that: include: Obtaining basic design parameters of the bridge structure, and setting three different levels of earthquake levels according to the earthquake intensity, and obtaining corresponding target spectra through the three different levels of earthquake levels, wherein the target spectrum is a force-displacement relationship curve; The bridge structure is equivalent to an ELSDOF single degree of freedom system, and the force-displacement response curve under the elastic state is obtained according to the equivalent ELSDOF system. The ELSDOF system force-displacement response curve and demand spectrum curve are established in the same coordinate system to obtain the performance target control points of three different levels of earthquake levels. The system control points of three different levels of earthquake levels are determined through the performance target control points of three different levels of earthquake levels, and the mechanical performance parameters of the steel stopper are obtained; Obtain the data of the system control points to calculate the displacements of the bridge piers and bearings at three levels, thereby obtaining the ductility coefficients of the piers and bearings, and judging whether the ductility coefficients of the bridge piers and bearings meet the target performance requirements; If it is satisfied, the result is output; if not, the mechanical parameters of the selected steel stopper are readjusted, and the system control points of three different levels of earthquake levels are re-determined until the ductility coefficient of the bridge pier and the ductility coefficient of the bearing meet the expected target performance requirements, and the result is output.

2. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake 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 the current different levels of earthquake levels according to the output results; The three different levels of earthquake levels include level one, level two and level three with increasing earthquake intensity, and the system control points include a first system control point, a second system control point and a third system control point; The first system control point includes: Calculate the load of the support and restraint system under the level 10 target performance, calculate the total stiffness and strength of the steel stopper, and the first stiffness of the quasi-isolation system; According to the relationship between the equivalent single degree of freedom and double degree of freedom, the total displacement of the system below the level is obtained, and the first system control point is determined.

3. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 2, characterized in that: The calculation of the load of the support restraint system under the level-10 target performance includes: In the formula, F bdy is the load of the supporting restraint system, m1 is the mass of the bridge superstructure, m2 is the mass of the bridge substructure, and F e1 is the base shear force of the ELSDOF system at the horizontal level.

4. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 2, characterized in that: The calculation of the total stiffness of the steel stopper includes: F by =μm1g F dy =F bdy -F by N=F dy / F d1 K d =NK d1 In the formula, F by is the friction force of the bridge superstructure, F dy The load borne by the steel stopper, N is the number of steel stops, F d1 is the yield strength of the steel stopper, K d is the total stiffness of the steel stopper, K d1 is the total stiffness of the single-piece steel stopper; The first stiffness of the quasi-seismic isolation system includes: K sy =K p The total displacement of the system below the level includes: In the formula, K p is the initial stiffness of the bridge pier obtained according to the general ductility design method, K sy is the first stiffness of the quasi-isolation system, Δ y is the total displacement of the system at the level below; Determine the first control point as (F y , Δ y ), F y To level the pier base shear force of the ENLSDOF system.

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

6. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 5, characterized in that: The second stiffness and the first stiffness ratio of the quasi-seismic isolation system include: In the formula, K sp is the second stiffness of the quasi-isolation system, K bd K is the parallel stiffness of all supports and steel stops, p is the initial stiffness of the bridge pier obtained according to the general ductility design method, k1 is the first stiffness ratio; The first energy correction coefficient includes: In the formula, γ a is the first energy correction coefficient, a1 is the first calculation coefficient under the first stiffness ratio k1, b1 is the second calculation coefficient under the first stiffness ratio k1, c1 is the third calculation coefficient under the first stiffness ratio k1, d1 is the fourth calculation coefficient under the first stiffness ratio k1, and T is the period of the ENLSDOF system.

7. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 6, characterized in that: The total displacement of the system under the second level includes: In the formula, Δ p is the total displacement of the system under level 2, F e2 is the base shear force of the ELSDOF system under level 2, Δ e2 is the top displacement of the ELSDOF system under level 2, F p is the pier base shear force of the ENLSDOF system under level 2; Determine the second system control point (F p , Δ p ).

8. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 7, characterized in that: The third system control point includes: The performance target control point under level 2 is obtained, 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-isolation and multi-level ordered earthquake resistance according to claim 8, characterized in that: The third stiffness and the second stiffness ratio of the quasi-seismic isolation system include: In the formula, K su is the third stiffness of the quasi-isolation system, K p2 According to the stiffness of the pier column after yield, K d2 is the stiffness of the steel stopper after yielding, k2 is the second stiffness ratio; The second energy correction factor includes: In the formula, γ a is the first energy correction coefficient, a2 is the first calculation coefficient under the first stiffness ratio k2, b2 is the second calculation coefficient under the first stiffness ratio k2, c2 is the third calculation coefficient under the first stiffness ratio k2, d2 is the fourth calculation coefficient under the first stiffness ratio k2, and T is the period of the ENLSDOF system; The total displacement of the system under the level 3 includes: In the formula, F u is the base shear force of the ENLSDOF system at level 3, F e3 is the base shear force of the ELSDOF system under level 3, Δ e3 is the top displacement of the ELSDOF system at level three.

10. A method for constructing a bridge with transverse quasi-isolation and multi-level ordered earthquake resistance according to claim 8, characterized in that: The determination of whether the ductility coefficient of the bridge pier and the ductility coefficient of the bearing meet the target performance requirements includes: The ductility coefficient of bridge piers and bearings must meet the following requirements: In the formula, μ b is the support ductility coefficient, μ p is the ductility coefficient of the pier column, Δ bdu is the limit displacement of the parallel system of the block and support of the quasi-isolation system, Δ by is the yield displacement of the quasi-isolation system support, Δ py is the yield displacement of the pier column of the quasi-seismic isolation system, [μ b ] is the support ductility coefficient threshold, [μ p ] is the threshold value of ductility coefficient of pier.

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