PSEUDO-DYNAMIC TEST OF A FULL-SCALE CFT/BRB FRAME:PART 1- PERFORMANCE BASED SPECIMEN DESIGN

摘要

This is the first of a three-part paper describing a full-scale 3-story 3-bay CFT buckling restrained bracedframe (CFT/BRB) specimen that was constructed and tested in the structural laboratory of National Centerfor Research on Earthquake Engineering (NCREE) in Taiwan using pseudo dynamic test (PDT)procedures and internet testing techniques in October of 2003. The frame was tested using the pseudodynamictest procedures applying input ground motions from the 1999 Chi-Chi and 1989 Loma Prietaearthquakes, scaled to represent 50%, 10%, and 2% in 50 years seismic hazard levels. This paperdescribes the displacement-based seismic design procedures adopted in the design of the structuralmembers. A target story drift limit of 0.025 radian for the 2% in 50 years hazard level governs the designstrength of the frame. Nonlinear analyses illustrate that the response of individual BRB member can besatisfactorily simulated by using truss elements implemented in two different general purpose nonlinearresponse analysis programs PISA3D and OpenSees. Pre-test nonlinear dynamic analyses suggest that thepeak story drift is likely to reach 0.025 radian after applying the 2/50 design earthquake on the framespecimen. CFT columns hinging at the base are expected, but should not fail as the rotational demand ismoderate. Analytical floor displacement and story shear time history response predictions were web-castduring the PDTs. Tests confirmed that the PISA3D and OpenSees analyses predicted the experimentalpeak shears extremely well. Experimental peak lateral floor displacements well agree with the prescribedtarget design responses for both the 10/50 and 2/50 two events. Tests also confirmed that experimentalpeak inter-story drifts of 0.019 and 0.023 radians well agree with the target design limits of 0.02 and0.025 radians prescribed for the 10/50 and 2/50 events, respectively.