| As an important part of lifeline system.substation plays an imponant role in economic construction and people's lifc.In recent years,the disastrous earthquakes have repcatedly shown that power facilities of substation havc high seismic vulnerability,poor seismic capacity and heavy earthquake loss.With continuous dcvelopmcnt of social economy in our country.the demand for electric power is constaru increasing,and reliabiliry and quality requires of power supply are higher and highcr,which lead to the numbcr of ncwly built and expanded substations increase significantly and more and more attention for their seismic safety.Whole indoor substation has the advantages of land conservation.beautiful appearance and environmental protection,reliable system.and so on.It accords with development concept of sman subsialion.strongly supports construction of strong smart grid.and is future development direction of substation.Howcver.in order to meet electrical process requirements,building strucrure of substation shows obvious irregularity.which is not conducive to earthquake resistant and threatens seismic safety of internal electrical facilities;Meanwhile.this type of subsiation is applicd for a short time,lack of actual earthquake damage accumulation,and seismic research is not sufficient,which limit its application and popularization in high earthquake intensity regions.In this paper,the first domestic whole indoor substation with overall isolation is taken as research object,and seismic performance of structure and corrcsponding non-isolated structurc are systematically and thoroughly studicd by using method of theoretical analysis combined with numerical simulation.First of all,seismic response of non-isolated structure is analyzed under frequent and rare carthquakcs.preliminary evaluating their seismic performance;then,according to presented isolated target,optimal seismic isolation schemc is determined;then,the difference between seismic response of isolated structures using different restoring force model of slide bearing and the effect of staged construction for seismic response of isolated and non-isolated structures are discussed;then,incremental dynamic analysis and seismic vulnerability analysis of two structures are carried out by using different ground motion intensity measures under unidirectional and bi-directional earthquake excitations;on the basis of this,probabilistic seismic risk analysis is carried out to evaluate seismic performance of non-isolated and isolated structures.The main research results are as follows:(1)The maximum acceleration of first floor is greater than that of second floor for non-isolated structure under frequent earthquake(0.07g),and excessive floor acceleration deteriorates equipment's operating environment;the whole structure or the local section that places main transformer collapses under rare earthquake(0.40g),and it is difficult for the structure to resist rare earthquake.It is necessary to enhance seismic capacity of structure in order to be applied in high earthquake intensity regions.(2)It is feasible and effective for whole indoor substation to use overall isolation.After isolation,acceleration reduction rate of each floor is more than 50%,and horizontal earthquake action of superstructure can be reduced one seismic intensity to calculate;superstructure is basically in elastic working state under rare earthquake,and there is no obvious elastic-plastic damage.The seismic performance of structure and safety reserve of equipment have been improved significantly.(3)The two kinds of restoring force models of sliding bearing can be in common use when structure is subjected to unidirectional or bi-directional seismic excitation;the FP model is suggested to use under three directional seismic excitation,in order to more accurately consider influence of dynamic axial force on bearing shear force and hysteretic behavior;if bearing exists tensile condition,the FP model should be used.(4)Putting into use by stage wills make structural mass distribution eccentric,but its effect on seismic response of isolated structure is very limited,which wills not endanger structure and equipment safety,and the reliability of substation normal operation is not reduced.While its effect on non-isolated structure is greater than that on isolated structure,leading to the certain security risk,so structural jointing and other measures are recommended to use to eliminate potential hazard.(5)The influence of different earthquake wave input directions on seismic response of the two structures is relative small,so variation of its incident angle can be ignored for structural seismic response analysis,and ground motion is directly input along main axises of structure;it is necessary to input bi-directional earthquake waves,which can more truly reflect seismic damage of structure,thus seismic performance evaluation is more reasonable and reliable.(6)The mode 0.135%of maximum interstory drift ratio response for superstructure of isolated structure under rare earthquake is close to 0.140%obtained by artificial rare earthquake wave.The result shows that artificial earthquake wave fitted by code spectrum can reflect the most probable earthquake demand of superstructure,partial to conservative,and it also indirectly proves rationality of the selected earthquake waves for incremental dynamic analysis.(7)The performance ranking of different ground motion intensity measure is not changed by input modes of earthquake wave and analysis types,which has a certain stability.PGV has closest relationship with seismic responses of the two structures,so it is an ideal ground motion intensity measure for them to carry out incremental dynamic analysis and seismic vulnerability analysis,and seismic performance evaluation results of the structures are more conservative and safe;but considering the connection between PGA and codes better,it can still be used as a reference.For non-isolated structure,seismic performance evaluation result obtained by using Sa(T1,5%)is the best,partial to economy,so result obtained by taking PGV or Sa(T1,5%)as ground motion intensity measure is more representative,and it is suggested to select first.(8)The seismic performance of non-isolated structure can be qualitatively described as"minor damage under frequent earthquake,reluctantly repairable under moderate earthquake,collapsing under rare and extremely rare earthquake",while that of isolated structure can be described as "basically intact under frequent earthquake,repairable under moderate and rare earthquake,basically no collapsing under extremely rare earthquake".The seismic performance of structure has been significantly improved,and seismic capacity of electrical facilities are indirectly enhanced,which increase reliability of substation safe operation under earthquake;however,it is possible for structure to collapse under ultra intensity earthquake,and isolation layer is anti-seismic weak position,which is noteworthy.(9)The seismic performances of two structures evaluated by probabilistic seismic risk analysis are basically same as the conclusions of their seismic vulnerability analysis,but the former is more refined and intuitive;the structural failure probability increases after considering itself uncertainty,so it is necessary to consider this factor to make evaluation result more comprehensive and reasonable. |
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