A study of the nonlinear behaviour of the irregular Beni Haroun cable-stayed bridge to progressive seismic failure under SVGM

Abstract

The progressive failure of the nonlinear irregular Cable-Stayed Bridges (CSBs) under Spatial Variability of Ground Motions (SVGM) counting seismic wave propagation, incoherence effect and site-response effect is investigated. A spectral representation method is used in order to develop a computer code. This code is used to simulate SVGM time histories to be compatible with an overall coherency function and a target response spectrum, A three-dimensional Finite Element Model (FEM) of an asymmetric bridge: the Beni Haroun cable-stayed bridge (CSB) (North Eastern Algeria) is developed in order to include the effects of the main components of SVGM on response parameters in terms of variations of absolute maximum vertical displacements and flexural moments along the deck and on height of short and tall pylons of study CSB, in particular, nonlinear bridge response quantities are examined in terms of rotational ductility demands at the ends of the short and tall piers of the bridge under all components of SVGM. The numerical results are comforted with those obtained assuming uniform seismic excitations. The analysis results reveal, among others, that the bridge responses are very sensitive to the SVGM, with site-response effects being more critical for bridge response than those of incoherence components and wave propagation. As a general trend, it is showed that the assumption of uniform excitation results in much lower ductility demands on bridges than incoherence and site SVGM components and that the latter should be considered for the seismic response assessments and progressive seismic failure studies of irregular cable-stayed bridges.