ABSTRACT
In Turkey which has a high seismic risk, it is required to design bridge structural systems so as to ensure a sufficient level of safety, as similar to other types of structural systems. In addition, it is of paramount importance to evaluate the seismic safety of existing bridge structural systems. In this context, currently it is often required to resort to deformation based performance evaluation methods in addition to the conventional strength based performance methods. In this paper, with reference to a particular project commissioned by Istanbul Metropolitan Municipality (IBB) which involved the inspection, evaluation and seismic retrofit of various existing bridges, the seismic performance of bridges have been studied and employed calculation methods explained. In this study, principles of “DLH Seismic Design Guidelines, General Directorate for Construction for Railways Harbours and Airports of (RHA) Ministry of Transportation (DLH 2008)” have been taken into consideration. Initially the existing bridge site inspections (cores, soil boring and structural in place measurements, etc) were carried out, followed by the establishment of structural calculation models. In the process which involved strength based evaluation response spectrum method, and on the other hand in the case of deformation based evaluation pushover analysis and nonlinear time history analysis have been performed. In the case of nonlinear analysis frame and finite element models have been used. By taking into account the particular bridge class and the expected performance level corresponding to this class, the seismic performance of bridges studied have been evaluated and those structures which exhibited insufficient level of seismic safety have been retrofitted.
