EFFECT OF PRINCIPAL AXIS ORIENTATION ON SEISMIC PERFORMANCE OF RC SHORT COLUMNS

摘要

This paper presents the results of shake table tests on six full-scale shear governed RC columns. Two types of RC columns were designed for the shake table tests. One is the column with an effective height of 0.6m and the other is 0.7m. The cross section of all the experimental columns is 0.3×0.3m<'2> with 6-#6 longitudinal steel rebars. The stirrup arrangements for the columns with a height of 0.7m or 0.6m are #2@ 10cm or #3@ 10cm, respectively. To evaluate the effect of the principal axis orientation on the seismic performance of RC short columns, in the three specimens of each type the principal axes of cross-section are in the directions of 0, 22.5, and 45 degrees to the excitation direction. The input ground motion for all tests is the acceleration time history recorded in the 1999 Taiwan Chi-Chi earthquake. The response time histories for the accelerations and displacements, as well as the force-displacement hysteretic loops are presented in this study. Based on the experimental results, the shear strength and ductility of columns with different principal axis orientations are further discussed and compared with those results obtained by conventional design formula.