The Research On Seismic Analyzing Approaches Of The Run-of-river Hydropower Station

With the ever accelerated development of the hydropower engineering, thestructural sizes of the run-of-river hydropower stations become much huger with theload path become more complicated. As is well known, the power station in the waterchannel is mainly used as both the center for the water power convergence and thedam which can gain the height of up-flow to reserve water energy. Thus, the dynamiccharacteristics of the run-of-river hydropower stations are very important for the dailyoperation. Besides, as the majority of hydropower projects are constructed in thesouthwest mountain regions of China which are the well known seismic sensitiveareas, the seismic response of the power plant structures is also highly related to thesafety of the project and citizens nearby in disastrous events.This dissertation paper is based on the structure of a run-of-river hydropowerstation which is located in the Lancang River, and the finite element analysis softwareAnsys is utilized to build two three dimensional structural models, with relateddynamic characteristics and seismic responses are studied. And the basic contents areas follows,First, in order to get the modes of vibration of this multi degree of freedom system,the free vibration of the whole power house is analyzed, and the factors which maycause structural vibration are studied and checked from hydraulic, mechanical,electrical aspects in order to prevent co-vibration. And a simplified model which onlyconcentrates on the upper structures is also built to check the availability and theaccuracy of this modeling approach which is always used in dynamic analysis of therun-of river hydropower stations.Second, the elastic response spectrums from both the European code, Eurocode8,and the Chinese Code are studied separately to analyze the structural response of thepower house during the earthquake activities. And the results from both approachesare compared.Third, the design response spectrum in Eurocode8is first used in the seismicanalysis of hydropower station, thus the energy dissipation and inelastic deformationcharacter of the power house are considered from linear analysis. Forth, the dynamic behavior of the structure under earthquake loads is also studiedthrough the time history analysis during the20-seconds artificial seismic wave whichis extracted from the elastic response spectra and the material nonlinearity of thereinforced concrete is also considered to check with the results before.Finally, After analyzing and comparing the stresses, strains and displacements ofthe powerhouse structure that are achieved from different calculating theories inseismic loads condition, some suggestions on suitable ways of seismic analysis areprovided and the main characteristics of the run-of-river hydropower stations duringearthquake activities are discussed.