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Abstract

The definition of the Spatial Variability of the Ground Motion (SVGM) is a complex and multi-parametric problem that has caught the attention of the research community since the first accelerometer arrays were installed. The effect of this phenomenon on the seismic response of long and multiply supported structures in general, and on cablestayed bridges, in particular, has been studied by many researchers who have emphasised the significance of considering this phenomenon in the seismic analysis, but have also agreed that the SVGM is a multi-component phenomenon that needs more research.

This work examines the effect of the multi-support excitation on the seismic response of cable-stayed bridges by means of the time delay of the earthquake at different supports and of the loss of coherency of the seismic waves. The focus herein is the effect of the SVGM on cable-stayed bridges with various configurations in terms of their length and in terms of design parameters, such as the pylon shape and the pylon-cable system configuration, combined with the influence of the incidence angle of the seismic waves. Furthermore, the SVGM is examined at higher levels of earthquake intensity in order to assess the vulnerability of the bridge when subjected to lower probability ground motions.

The aim of this research is to provide general conclusions that are applicable to a wide range of cable-stayed bridges and to contribute to the ongoing effort to interpret and predict the effect of the SVGM.

It has been found that the influence of the multi-support excitation on the seismic response of the bridges is strongly affected by the shape of the pylons, by the pylon-cable system configuration and by and the seismic incidence angle. The SVGM also excites vibration modes that do not contribute to the seismic response when identical support motions are considered and it increases the probability of failure in the constituent components of the bridge.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TG Bridge engineering
Departments:	Doctoral Theses School of Science & Technology > School of Science & Technology Doctoral Theses School of Science & Technology > Engineering

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