Methodologies for Assessing Bridge Performance Under Seismic Action

Abstract

This paper analyses the seismic response of four continuous precast prestressed concrete girder bridges, with total lengths ranging from 80 m to 200 m, representative of Romanian road infrastructure. The structures were initially designed with neoprene elastomeric bearings, in compliance with the Romanian code for seismic design P100-1/2006 [1]. The seismic performance of the bridges was assessed through nonlinear static (Pushover) analyses using the FEMA 440 [2] equivalent linearization procedure, for five seismic hazard levels (return periods of 100, 225, 475, 970 and 2475 years). Results highlighted a significant vulnerability of the conventional neoprene system at moderate seismic intensities, with displacement demands exceeding the nominal bearing capacity from a return period of 225 years onwards. As an alternative, a pot bearing system was investigated, allowing larger displacements and providing more controlled seismic behavior. The study demonstrates that pot bearings reduce spectral accelerations by up to 54%, but increase the behavior factors, while maintaining bearing integrity at higher seismic hazard levels.