Seismic Isolation Analysis Of Hospital Building Under Near-Fault Pulsed Ground Motion

The displacement pulse motion and long period velocity of the near-fault pulsed ground motion have an obvious amplification effect on the ductility demand and seismic response of the structure,which will have an adverse effect on the seismic design of the structure.In this paper,the hospital building in the earthquake to bear the function of medical rescue,can minimize casualties,related to social public safety,is the focus of earthquake fortification.In the national standard "Classification Standard for Seismic Fortification of Building Engineering"(GB 50223--2008),hospital buildings are divided into key fortification category(Class B).Therefore,it is particularly important to study the seismic isolation technology of hospital buildings under the action of near-fault pulsed ground motion.Therefore,taking Qujiang Hospital complex building project of Xi ’an city as an example,the finite element structural analysis software(SAP2000)is used to design the structure for shock reduction and isolation.Based on different seismic isolation arrangement schemes,this paper studies the seismic performance of hospital building structures under the action of near-fault pulse type ground motion,and provides certain reference for improving the seismic performance of hospital buildings and the design and research of seismic isolation of hospital buildings.The main work and conclusions are as follows:(1)The seismic impact coefficient of the near-fault pulse seismic wave Chi-Chi＿Taiwan wave,Landers wave,El Mayor-Cucapah＿Mexico wave is extracted and compared with the maximum earthquake impact coefficient in Xi ’an area.The seismic influence coefficient of three near-fault pulse seismic waves is about 3 times that of the seismic fortification earthquake.(2)Through the modal analysis of the structure,it is concluded that compared with the original structure,the first order natural vibration period of the structure is significantly increased in the three schemes of foundation isolation structure.Compared with the original structure,the natural vibration period of scheme 1(arranged with VFD)is basically unchanged,Scheme 2(arranged with BRB)is reduced,and scheme 3(arranged with both VFD and BRB)is slightly reduced.The analysis results show that the seismic isolation layer can effectively reduce the seismic response to the structure,reduce the structural stiffness and increase the structural period.The energy dissipator can absorb the ground motion energy,reduce the earthquake response to the structure,increase the structure stiffness,and reduce the structure cycle.(3)The time-history analysis of the original structure,the isolation structure and the energy dissipation and shock absorption structure under earthquake protection shows that the interlayer shear of the original structure is significantly reduced compared with the three kinds of foundation isolation structure;Compared with the interlayer shear of the three energy dissipation structures,the shear of the original structure decreases obviously,but the damping effect is lower than that of the isolated structure.The analysis results show that the foundation isolation structure can reduce the interlayer shear more effectively than the energy dissipation structure.(4)The time-history analysis of the near-fault pulsed ground motion on the original structure,the optimal foundation isolation scheme and the energy dissipation and damping structure scheme shows that the floor displacement,interfloor displacement Angle and floor shear of the foundation isolation are significantly reduced compared with the original structure;Compared with the original structure,the floor displacement,interfloor displacement Angle and floor shear of the building structure with energy dissipation and vibration absorption are significantly reduced.The results show that the foundation isolation structure has better damping effect than the energy dissipation and damping structure under near-fault pulse ground motion.(5)The analysis of seismic wave energy dissipation of foundation isolation structure and energy dissipation damping structure under near-fault pulse ground motion shows that both structures can reduce the damage of seismic wave energy to the structure,and the average energy dissipation of foundation isolation structure is greater than that of energy dissipation damping structure.By comprehensive analysis;The energy consumed by the foundation isolation structure is better than that of the energy dissipation and damping structure.Therefore,the base-isolated structure can be used as the optimal aseismic design.