Seismic Performance Analysis Of A Frame Structure Teaching Building Under Multi-dimensional Ground Motion

Recently,earthquake is becoming one of the devastating disasters all around the world.Due to the complex and intense ground motion in earthquakes,the structure may suffer serious damage even collapse,but the complex and intense ground motion have not been fully considered in current structural design and scientific researches and only the influence of single horizontal earthquakes to the dynamic response of structures is considered.Large number of seismic hazard and theoretical researches have shown that strong ground motion consists of multiple components instead of a simply unidimensional movement.And a number of provisions about two-dimensional earthquake and three-dimensional earthquake have been proposed by GB 50011-2010,Code for seismic design of buildings.Some status of researches on multi-dimensional earthquake excitations for structures are summarized,and three analytical methods and three finite element analytical models have been elaborated in this paper.Five suits ground motion records,the PGA of which have been adjusted to fortification intensity and rare intensity,have been input a finite element model of a 6-story reinforced concrete frame teaching building,in which the dynamic responses under single horizontal earthquake,two horizontal earthquake and three-dimensional earthquake have been compared.In comparison,four damage states proposed by GB 50011-2010,Code for seismic design of buildings,which are good state and its limit of interstory drift is 1/550,slight damage state and its limit of interstory drift is 1/250,moderate damage state and its limit of interstory drift is 1/120 and inelastic storey drift limit which is 1/50,have been selected as reference standards to research the seismic performance of structure.The follow conclusions have been obtained from these researches.1.The dynamic response of structures under two-dimensional earthquakes is obviously exceed the dynamic response of structures under single horizontal earthquakes,and the damage results from the two conditions are so large different that it caused two different damage states when compare the damage degrees obtained from the two conditions to the aforementioned four damage states.It may cause worse influences on strengthening and repairing of structures after earthquakes.2.The dynamic response of structures under three-dimensional earthquakes is obviously exceed the dynamic response of structures under single horizontal earthquakes.The damage degrees caused by three-dimensional earthquakes and two-dimensional earthquakes are almost under the same damage state.3.Comparing to the influences of two-dimensional earthquakes and single horizontal earthquakes to the structure,the weak story of structures under three-dimensional earthquakes is transferred to other stories,which may because vertical seismic motion caused the failure mode of structures changed and accumulative damage of structures occurred.4.The vertical seismic motion may cause obvious influence to bottom layer of structures,and the influence is gradually reduced with the increase of floor.