Dynamic Responses And Seismic Response Reduction Of Sliding Isolation Concrete Rectangular Liquid Storage Structure

Earthquakes can cause damage to the liquid storage structure(LSS)itself,moreover,the leakage of some special liquids will lead to secondary disasters such as environmental pollution and fire,and the most serious consequence is that the security of people's lives will be threatened.In many previous earthquakes,there were many cases of destruction of LSSs.In recent years,the frequency of earthquake occurrence has been increased worldwide,at the same time,the LSSs are developing towards large scale and large quantity,and the types of stored liquids are also increasing,as a result,the probability and threat of the destruction of LSSs under earthquake action are greater.As an effective measure,isolation can improve the seismic resistance of structure and reduce the failure probability of structure under the action of earthquake.Relative to the common rubber isolation,sliding isolation has a good prospect of application because of its simple material,simple structure,low cost and special seismic response reduction advantage.In this paper,some researches have been carried out on the sliding isolation concrete rectangular LSS.The main research contents are as follows:(1)Combining sliding isolation and limiting measure,a shock absorption method suitable for concrete rectangular LSS is formed,and the simplified mechanical model and numerical calculation model of the system are established.From the perspective of safe use of LSS and the deformation capacity of the limiting-device,the horizontal displacement limit of sliding isolation LSS is defined.The influences of parameters of the limiting-device on its hysteretic energy and the system dynamic responses are discussed.The seismic response reduction effect of sliding isolation with limiting-devices on the concrete rectangular LSS under near-field earthquake action is studied.Besides,the parameter influence analysis is carried out and the dynamic responses of the system under horizontally unidirectional and bidirectional near-field earthquake actions are comparatively studied.(2)The characteristics and identification methods of long period ground motion are summarized,and synthetic procedures of far-field long-period ground motion based on the stochastic method are given.Numerical models of sliding isolation concrete rectangular LSSs with different length-width ratio are established,the particularities of dynamic responses and the corresponding seismic response reduction effect of sliding isolation concrete rectangular LSS are studied under far-field long-period earthquake action,and control measures for horizontal displacement of sliding isolation concrete rectangular LSS under far-field long-period earthquake action are investigated,besides,design suggestions for sliding isolation LSS under far-field long-period earthquake action are given.(3)Based on the potential flow theory,the lower limit of large amplitude liquid sloshing of rectangular LSS is defined,and the nonlinear theory based on two-way coupling is adopted for large amplitude liquid sloshing.The three-dimensional models of sliding isolation concrete rectangular LSS with limiting-devices and liquid are respectively established.The earthquake action is simulated in the form of displacement loading at the bottom of the sliding isolation LSS.The structure domain is solved by Newmark-? method,and the liquid domain is solved by Euler method.The results obtained by the two-way coupling theory and ADINA nonlinear potential flow theory are compared.The seismic response reduction effect of sliding isolation on concrete rectangular LSS under large amplitude liquid sloshing is studied,and the effects of seismic dimension,liquid level height,seismic amplitude and excitation frequency on the dynamic responses of the system are also discussed.(4)Considering the sloshing effect of the liquid free surface,the velocity potential function of the sliding isolation rectangular LSS is derived by the superposition principle,and the simplified formulas of hydrodynamic pressure,liquid sloshing height,base shear and base bending moment are obtained by the velocity potential function.In the moving coordinate system,the kinematic and dynamic boundary conditions that should be satisfied on the liquid free surface are obtained.The liquid domain is solved based on computational fluid dynamics(CFD),and the pressure action is introduced into the dynamic control equation of structure to reflect the influence of the liquid.The case that the free surface liquid sloshing is not considered is simulated by exerting vertical displacement constraint on the free surface,and the dynamic responses of the system are comparatively studied considering the free surface liquid sloshing or not.(5)The defect of sliding isolation is that pounding will be caused once the horizontal displacement exceeding the initial gap between the structure and the retaining wall.Based on the contact element method,the Hertz-damp nonlinear model is used to simulate the transient pounding effect between the concrete rectangular LSS and the retaining wall,the foundation is simulated by the lumped parameter model,simplified calculation models for the collision problem of sliding isolation concrete rectangular LSSs are established considering the foundation effect or not,and the nonlinear collision problem is numerically simulated by using MATLAB.The influences of pounding on the dynamic responses of LSS and the main factors affecting the pounding responses are studied.In order to mitigate the adverse effects of pounding on the LSS,a buffer layer is arranged on the surface of the retaining wall,material nonlinearity of the buffer layer is considered in the pounding model,and the effects of pounding mitigation measures on the coefficient of restitution and the dynamic responses of LSS are studied.(6)Considering the important characteristics of sliding isolation concrete rectangular LSS under some earthquake actions,such as fluid-structure interaction(FSI),material nonlinearity,liquid sloshing nonlinearity and contact nonlinearity,a three-dimensional nonlinear numerical model is established.The failure criteria of sliding isolation concrete LSS are given,and based on the incremental dynamic analysis(IDA)method and fragility analysis method,a procedure for study of seismic performance of sliding isolation concrete rectangular LSS is proposed.The seismic fragilities of no-isoaltion LSS,pure sliding isolation LSS and sliding isolation LSS with limiting-devices under near-field pulse-like,near-field no-pulse and far-field earthquake actions are studied,and the main factors affecting the seismic performance of sliding isolation concrete rectangular LSS are investigated.(7)In order to further verify the effectiveness of sliding isolation on seismic response reduction of concrete rectangular LSS,near-field and far-field long-period earthquake waves are chosen,and the dynamic responses of no-isolation LSS,lead rubber bearing LSS,sliding isolation LSS with steel bar limiting-devices,and sliding isolation LSS with spring limiting-devices are comparatively studied by shaking table test.The seismic response reduction advantage of sliding isolation on concrete rectangular LSS is discussed.The control effect of limiting-devices on the sliding displacement of the structure and the influences of limiting-device types on the dynamic responses of the system are analyzed.Besides,suggestions for reasonable application of sliding isolation in concrete rectangular LSS are given.