Affiliations: [a] Department of Civil Engineering, Kharazmi University, Moffateh Avenue, Tehran, Iran
| [b] Department of Geotechnical Earthquake Engineering, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
Corresponding author. Shima Sadat Hoseini, Department of Civil Engineering, Kharazmi University, Moffateh Avenue, Tehran, Iran. E-mail: [email protected].
Abstract: This paper presents the result of a study on the effect of Spatially Varying Earthquake Ground Motions (SVEGM) on the dynamic responses of a long span bridge and the influence of soil types on SVEGM. The spatial ground motions are simulated according to conditional method by SIMQKE II record generator, based on real Northridge- 1994 earthquake time history in different soil types. The influence of soil type to change the time history along the bridge supports and the necessity of considering the SVEGM in dynamic analysis of long span bridges are investigated. State space method is used to solve the equation of motion directly in time domain. To emphasize the importance of spatial variability effects of earthquake ground motion, fixed base model of bridge is used, which neglects the soil-structure interaction. The study reveals that the assumption of uniform ground excitation in the analysis and design may not provide a realistic estimation of the dynamic response of long span bridges, specially, in medium and soft soil. Pounding potential of bridge adjacent decks, as an important dynamic design factor, is also increased significantly, specially, in firm and medium soil.
Keywords: Spatially Varying Earthquake Ground Motions, uniform excitation, long bridges, State space, pounding, SIMQKE