3-D Collapse Tests and Analyses of the Three-Story Reinforced Concrete Buildings with Flexible Foundation

Abstract

Full-scale shake table tests were planed and conducted at E-Defense from September to November 2006 in the second phase of the Dai-Dai-Toku project. Two three-story specimens on flexible foundation, the bare specimen and the retrofit specimen, were tested with the following specific objectives: (1) the simulation of progressive collapse of existing school buildings, (2) verification of strengthening effect by the attached steel frames, and (3) soil-structure interaction with flexible foundation. Backgrouds of the test plan and the details of the specimens are reported in another paper, while analyses and mesured responses are reported in this paper. For the planning of the test specimens, preliminary nonlinear pushover analysis and dynamic analysis were carried out. The bare specimen was supposed to fail in shear before/after flexural yielding of the short columns. The effect of the dislocation at the flexible base and the brittle shear failure of the columns on the failure modes were considered in the analysis. An overall mechanism of rocking was to be observed in the retrofit specimen with the steel braces and seismic slits. In this paper, the preliminry analyses of the two specimens and the observed behavior of the two specimens in the shake table test are presented mainly focused on the failure mechanisms of the structure considering the base conditions. The results of the static test to identify the base friction coefficient are also reported.