Abstract: Bridges are lifeline structures and their performance is critical during and after the earthquake. The RC Bridge decks, supported on unanchored elastomeric pad bearings are free to move over substructure during an earthquake. Excessive deck displacement causes unseating and sometimes complete collapse of the deck leading to closure of the bridge for long periods. The problem worsens for irregular bridge with significant variations in the pier/pile heights. For example, decks of 268 m long Chengappa bridge across Austen Strait in Andaman islands was unseated during the 2004 Sumatra-Andaman earthquake, which had taller piers in the middle for navigational purposes. The bridge was modelled in AutoCAD and exported to CSI SAP2000 software to analytically investigate the performance of the bridge using the finite element (FE) analysis. The FE model was able to predict the observed response in the 2004 Sumatra-Andaman earthquake for comparable ground motions. Under design level earthquake ground motions, the model experienced unseating of the decks and possible collapse indicating higher vulnerability of irregular bridges with unanchored elastomeric pad bearings. A suitable retrofitting technique is proposed in the form of restrainers in order to arrest the displacement of deck slab and girders.
Keywords: Irregular Bridge, Response Spectrum Analysis, Deck Displacement, Restrainer, Time History Analysis.
Title: SEISMIC MITIGATION PERFORMANCE ANALYSIS STUDY OF IRREGULAR BRIDGES
Author: Sadic Azeez, Rincy P M
International Journal of Civil and Structural Engineering Research
ISSN 2348-7607 (Online)
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