Abstract
This paper presents an analysis on the importance of clarifying the difference of column ductility factor and system ductility factor for two bridges which are supported by flexible elastomeric bearings. Assuming a column-foundation-elastomeric bearing-deck system, the relation of column ductility factor and the system ductility factor is presented. It is found from a series of nonlinear and linear dynamic response analysis that the deck accelerations evaluated by the force reduction factors based on the system ductility factor are closer to the deck accelerations computed by the nonlinear dynamic response analysis while the deck accelerations evaluated by the force reduction factors based on the column ductility factor are extremely underestimated. It is also found that the deck displacements evaluated by the displacement increasing factor based on the column ductility factors are overestimated. It is thus concluded that the system ductility factor should be used to evaluate the force reduction factor for deck accelerations and the displacement increasing factor for deck displacements.
