Probabilistic approach to seismic evaluation of SDOF systems :|highway bridges

Abstract

In this study, a computational tool was developed to perform sectional analysis and to determine the force - displacement relationship, and then the displacement capacity of a fixed-base cantilever column. Also, a nonlinear time history analysis code was written to determine the displacement demand of a SDOF system. The stiffness degrading and pinching hysteretic model was also adapted in the dynamic analysis. 50 artificial earthquake ground motions corresponding to specific response spectrum values were generated and used in the time history analysis to analyze 96 different SDOF structures. Therefore, using the computational tool, first, the force - displacement relationship was found according to a given column cross-section and its displacement capacity was determined. Secondly, by using the previously obtained force - displacement relationship, displacement demands were determined. Finally, using 10 different ground motions corresponding to one response spectrum, displacement capacity and displacement demand ratios were obtained. The parameters involved in the overall analysis were axial load to ultimate axial load capacity, P/P0, ratio, the longitudinal reinforcement ratio, r, the cylinder strength, fc', and the aspect ratio, L/D.Finally charts showing the probability of failures were presented for different seismic zones, reinforcement ratios and P/P0 ratios. The recommendations based on the obtained results are proposed to use for the preliminary seismic screening of SDOF systems.