The number of traditionally excellent coastal lithologic nuclear power plants is *** is a trend to develop nuclear power plants on soil sites in inland ***,the seismic safety and adaptability of non-rock nuclear power...
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The number of traditionally excellent coastal lithologic nuclear power plants is *** is a trend to develop nuclear power plants on soil sites in inland ***,the seismic safety and adaptability of non-rock nuclear power plant(NPP)sites are the key concerns of nuclear safety *** the five site categories are clearly defined in the AP1000 design control documents,the effects of nuclear power five site conditions and soil nonlinearity on the seismic response characteristics of nuclear island buildings have not been systematically considered in previous related *** this study,targeting the AP1000 nuclear island structure as the research object,three-dimensional finite element models of a nuclear island structure at five types of sites(firm rock site(FR),soft rock site(SR),soft-to-medium soil site(SMS),upper bound soft-to-medium site(SMS-UB),and soft soil site(SS))are *** partitioned analysis method of soil-structure interaction(PASSI)in the time-domain is used to investigate the effects of site hardness and nonlinearity on the acceleration,displacement,and acceleration response spectrum of the nuclear island structure under seismic *** incremental equilibrium equation and explicit decoupling method are used to analyze the soil nonlinearity described by the Davidenkov model with simplified loading-reloading *** results show that,in the linear case,with the increase of site hardness,the peak ground acceleration(PGA)and the peak of acceleration response spectrum of the nuclear island structure increase except for the FR site,while the maximum displacement *** nonlinear analysis,as the site hardness increases,the PGA,maximum displacement,and the peak of acceleration response spectrum of the nuclear island structure *** peak value of the acceleration response spectrum in the nonlinear case is greater than that in the linear case for FR,while smaller for SR and soil *** site nonlinear
The present methods for three-dimensional time-domain soil-structure interaction (SSI) analysis are often uneconomical because they are performed with a single time integrationscheme and a single time step, which pro...
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The present methods for three-dimensional time-domain soil-structure interaction (SSI) analysis are often uneconomical because they are performed with a single time integrationscheme and a single time step, which prohibits their application to large-scale SSI problems. In this study, a partitioned analysis of SSI (PASSI) is proposed for enhancing SSI computational efficiency. This is accomplished by partitioning the soil-foundation-structure system into the soil (foundation) and structure subsystems and implementing the continuity conditions of the displacements and reaction forces at the soil (foundation)-structure interface in a primal way. A lumped-mass explicit finite element method and a transmitting artificial boundary are used to model the unbounded soil, the structure is analyzed via the implicit finite element method, and the response of the rigid foundation is calculated through an explicit time integrationscheme. The solution is separately advanced over time for each subsystem. Different time steps can be chosen for the explicit and implicitintegrationschemes, which can greatly improve efficiency. Interaction effects are accounted for by the transmission and synchronization of the coupled state variables. In addition, intrafield and interfield parallel procedures for PASSI are developed, and their theoretical efficiencies are analyzed. A simple example is provided to verify the performance of the partitioned approach with an explicit-implicit co-computation and to compare it to the fully explicit approach. Finally, the seismic response analysis of a nuclear power plant is presented to validate the feasibility and efficiency of the intrafield and interfield parallel procedures.
For the current state-of-practice in soil-structure interaction (SSI) of nuclear facilities, the strain-dependent characteristics of soil are considered indirectly via equivalent linear methods in the frequency domain...
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For the current state-of-practice in soil-structure interaction (SSI) of nuclear facilities, the strain-dependent characteristics of soil are considered indirectly via equivalent linear methods in the frequency domain, typically represented by the SASSI program. SSI analysis in the time-domain, although directly involving material nonlinearity of the soil, is inefficient in practice up to now. Based on Partitioned Analysis of SSI (PASSI), a method for nonlinear soil-structure interaction analysis is developed in this paper, by applying implicit time-step integration and explicit one with different time steps to nuclear island and to soil, respectively. The incremental equilibrium equation and explicit decoupling method are used to analyze the soil nonlinearity described by the Davidenkov model with simplified loading-reloading rules, which avoids solving algebraic equations and iteration processes. An asynchronous parallel algorithm for nonlinear SSI analysis is given. A simple example is given to verify the partitioned approach with explicit-implicit co-computation against the full-explicit approach. Seismic response characteristics of nuclear power plants are investigated by comparing responses of nonlinear analysis with linear analysis. Different results address the importance of nonlinear SSI analysis for the seismic performance of nuclear structures.
An efficient method is proposed for transient response analysis of general three-dimensional structures resting on viscoelastic halfspace subjected to either external loads or seismic motions. The formulation consists...
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ISBN:
(纸本)9789076019314
An efficient method is proposed for transient response analysis of general three-dimensional structures resting on viscoelastic halfspace subjected to either external loads or seismic motions. The formulation consists of two parts: (a) the time domain formulation of the unbounded soil which is modeled by lumped-mass finite element and transmitting boundary condition and (b) the coupling of the corresponding soil algorithms to the finite element code for structure analysis. As far as the structure is concerned, this coupling opens the way for the analysis of non-linear soil-structure interaction. The explicit-implicit integration scheme is used in this method, and the efficiency can be greatly improved by using different time step in explicit time integration for soil analysis and implicit time integration for structure analysis. Examples are given to demonstrate the feasibility of this method.
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