Shaking Table Test Study On Seismic Responses Of Isolated Structure Under Near-fault Ground Motions

With the rapid development of the isolation technology, more than1000square meters ofbase-isolated buildings have been built in Beijing, Tianjin, Sichuan, Xinjiang, Guangdong andother places, which have basically covered the middle and high seismic region of our country.Previous reasearch about the seismic response of isolated structure mainly based onobservation record of ordinary far-field earthquake. However, our country is abundant inseismic zone and earthquake fault. So many cities such as Beijing, Tianjin, Xi ’an, Urumqi,Chengdu and other cities are under the potential threat of near-fault ground motions. Thus itcan be seen:the large-scaled promotion of isolated structure must be under the threat ofnear-fault ground motions.How to design and reinforce the isolated structures at the near-faultregion?It need to be studied and solved at present.It will do some reasearch around the two topics of near-fault ground motion and isolatedstructure in the paper.According to the previous research result,8parameters of groundmotion was selected to caracterize the the characteristics of near-fault ground motion.Different base-isolated structure modelings were built by SAP2000.They were used incalculating the dynamic response of base-isolated structures under the near-fault groundmotions.Then, in order to choose the damage potential parameters that will be helpful innear-fault seismic waves input, it analyzed the influence of the seleced8parameters ofnear-fault ground motion on dynamic responses of base-isolated structures by the use of theprinciple of relevance.Finally,a shaking table test of a steel frame base-isolated structure wasdesigned and conducted to detailedly study the seismic responses of base-isolated structuresunder near-fault ground motions and its regularity of distribution,to investigate the damagepotential of different parameters of near-fault ground motion.The main conclusions of this paper can be summarized as follows:(1) For thebase-isolated structures with different natural vibration periods,the influence of near-faultseismic waves on kinds of seismic responses of base-isolated structrues is different wheatherthe near-fault seismic waves containing velocity pulses.(2) All of the seleced8parameters ofnear-fault ground motion are related to the seismic responses parameters of base-isolatedstructure,but the reliability coefficient is different. The influence of input energy on dynamicresponses of base-isolated structrue is maximum. The reliability coefficient between PGV,PGD,PGV/PGA,PGA, Tp/T1,fault distance and dynamic responses of base-isolated structrueare pronounced apart from the earthquake duration. The damage potential of parameters ofnear-fault ground motion to structrue is related to the natural vibration period of base-isolatedstructure and wheather the near-fault seismic waves containing velocity pulses,etc.(3)Theshaking table test results proves the correlation of the parameters of near-fault ground motionand dynamic responses parameters of base-isolated structrue.(4) Multiple parameter controlmethod is proposed to choose near-fault ground motion records in base-isolated structureanalysis. For the base-isolated structures with different natural vibration periods,different seismic controlling parameters could be chose.That would provide design basis for theperformance-based aseismic design.The result of this study provides certain reference value for the performance-basedisolated structure design that consider the near-faul ground motion.It also provides support toestablish systematic and applicative isolated structure near the faul design method andstructure reinforcement theory.