SHAKING TABLE RESEARCH ON A CFST ARCH BRIDGE MODEL:EFFECT OF SITE CONDITION
To study the effects induced by varying sites on seismic responses of a CFST arch bridge,an actual CFST based scaled(1∶16) model has been employed to conduct the shaking table test.Based on the local sites classification of NEHRP,several real recorded ground motions at different site conditions from the ChiChi Earthquake are selected as the ground motion input,and then a comparative test on the multi-shaking table array system was carried out.During this experiment,the structure subjected to the uniform excitation are investigated,by considering the cases of longitudinal,transverse and vertical ground motion input,as well as the combination of transverse and longitudinal input and transverse and vertical input.This study reveals that local site condition has a significant influence on the seismic response of the CFST arch bridge.The seismic response increases with the site classification from A to E,and the seismic response in the E-class site is around 1.6~4.1 times high than that in the A-class.The vertical acceleration response of a vault is much more sensitive to site condition than the horizontal.As a result,the peak value of vertical design spectrum will be smaller if the same site coefficient is used with the horizontal one.