Seismic Safety of Existing Bridges (AGB2003/014)
Overview
Background & policy context:
The new Swiss standard SIA 261 prescribes seismic design actions significantly larger than in the past. Therefore, 90% of the Swiss bridges isn’t properly designed or isn’t designed at all to withstand an earthquake. Such bridges are characterized by an unknown seismic performance and their vulnerability is also mostly unknown.
To overcome this problem ASTRA developed a two stages assessment procedure for existing girder bridges. In the first stage the all bridges are assessed and the ones showing excessive vulnerability identified. Such bridges are analysed in depth during the second stage. To accomplish this task it is recommended to make use of displacement-based procedures.
Objectives:
Goal of the research project is the numerical and experimental analysis of existing girder bridges. The analysis aims in the development of displacement based assessment procedures for this kind of bridges. Such assessment procedures are particularly suited for regions of moderate seismicity. In many cases they allow a more favourable assessment of the available seismic safety. Hence, it is expected that the seismic safety of the majority of Swiss girder bridges is suitable even without retrofitting.
Methodology:
The research project starts with a literature review. Subsequently, the seismic behaviour of girder bridges is investigated based on numerical simulations and experiments. Practical design rules are derived ultimately based on theoretical studies.
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