Flexibility of superstructures and supports in the seismic analysis of simple bridges

✍ Scribed by Alfawakhiri, Farid; Bruneau, Michel

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 175 KB
• Volume: 29
• Category: Article
• ISSN: 0098-8847
• DOI: 10.1002/(sici)1096-9845(200005)29:5<711::aid-eqe936>3.0.co;2-#

✦ Synopsis

This paper addresses the elastic dynamic response of simply supported bridges to ground motion in their transverse direction. The interaction between superstructure and support #exibilities is studied in a systematic manner for symmetric spans. The bridges are modelled as beams with uniformly distributed mass and elasticity, simply supported at the ends by elastic springs. It is shown that a dimensionless sti!ness index, which re#ects the relative sti!ness of the superstructure compared to the sti!ness of the substructure, completely de"nes the dynamic mode shapes of the model. Useful closed-form expressions, based on approximate shape functions, are derived for the dynamic parameters of the "rst mode, and their accuracy is assessed. The e!ect of the sti!ness index on these dynamic parameters is investigated. Numerical case studies are presented to illustrate the use of proposed equations in the seismic analysis of bridges.