Study On Seismic Vulnerability And Reliability Of Multi-story Frame Structure Of School

Nowadays the function and structural style of buildings havebecome more and more complex, to reduce seismic loss, it is gettingmore and more important that structures with different important aredesigned by different classification and the seismic ability of buildingswith different uses is estimated accurately, for instance, the teachingbuilding of middle and primary school, which are related to life safetyof a large number of children. The seismic vulnerability and reliabilityanalysis of structures are the premise of the work mentioned above. Inthis paper, based on the background that multi-story frame widely usedin middle and primary school were damaged seriously in the greatearthquakes in our country recently, the seismic vulnerability andreliability of multi-story frame structure designed according to thecurrent design code, designed according to the last generation designcode, and designed according to the last generation design code butstrengthened by wing walls were studied. The necessary basis forimproving the seismic safety of such buildings and for establishingmeasure of disaster prevention and reduction were provided in thisstudy.The development of structural seismic reliability analysis wasreviewed. Several reliability calculation methods were introduced andsummarized. These methods could be divided into four categories,which were, First-order Second-moment Method (FOSM), based onperformance functions, not applied to complex structure systems;Monte-Carlo method, based on statistical methods, widely used withhuge computation; response surface method, combined the twomethods above; direct probability density integration method, whichthe seismic probability of occurrence is described by knownprobability.The probability Pushover analysis method which belongs to thefourth categories was selected and modified in this paper, as the method of analyzing the seismic vulnerability and reliability ofstructures. The theoretical basis of probability Pushover analysismethod were first introduced, i.e., the stochastic theory of responsespectrum and the Pushover analysis method. The problem of the equalprobability sampling of the structure random variable was solved, andthe method calculating the structural equivalent first period used inATC-40was improved to be appropriate for a large number ofcalculations of structure samples. The steps of the original probabilityPushover method were improved, connected completely, and combinedorganically. Based on the OpenSees platform, the computer programsof the revised probability Pushover method was completed.Three kinds of middle and primary school teaching building weredesigned, which according to the current design code, according to thelast generation design code, according to the last generation designcode but strengthened by wing wall. The seismic vulnerability andreliability of buildings were analyzed by using the computer programmentioned above. In this process, the detailed comparison of therelated specification clauses about multi-storey reinforced concreteframe structure between the last generation design code and the currentdesign code were shown. Based on these codes, the multi-story framewidely used in southern middle and primary school were designed inaccordance with the VI, VII, VIII, IX intensities as the typicalstructures, and strengthened by wing wall. The seismic vulnerabilitycurve and reliability for each typical structure were calculated andobtained by using the computer programs mentioned above. Thegeneral buildings such as office building were also designed assupplement study according to the current design codes, and theirseismic vulnerability and reliability were calculated and comparedwith the other kind of structures. The conclusions were obtained asfollowing: for teaching building of middle and primary school in theregion of VI and VII degrees fortification, the structure designedaccording to the last generation design code and strengthened by wingwall could reach the reliability level of current design code, whilethose in the region of VIII and IX degrees fortification couldn’t reach. However, for the general buildings, in the region of VI, VII and VIIIdegrees fortification, the structure designed according to the lastgeneration design code and strengthened by wing wall could reach thereliability level of current design code, while those in the region of IXdegrees fortification couldn’t reach.