Effects of Soil-Structure Interaction on the Inelastic Seismic Response of Continuous Bridges on Piled Foundation
Amin A-M. Kotb1, Sameh S.F. Mehanny2, Osman O.M. Ramadan3

1Amin A-M. Kotb Structural Engineering Department, Higher Institute of Engineering at El-Shorouk City, Cairo, Egypt.
2Sameh S.F. Mehanny, Structural Engineering Department, Cairo University, Egypt.
3Osman O.M. Ramadan*, Structural Engineering Department, Cairo University, Egypt, and Dean of Higher Technological Institute.
Manuscript received on July 20, 2019. | Revised Manuscript received on August 10, 2019. | Manuscript published on August 30, 2019. | PP: 1282-1290 | Volume-8 Issue-6, August 2019. | Retrieval Number: F8503088619/2019©BEIESP | DOI: 10.35940/ijeat.F8503.088619
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: Effect of soil-structure interaction (SSI) on seismic response of bridges is not clearly understood, and in general practice, bridge design is carried out ignoring its effect. This is due to the general consensus that fixed base leads to a more conservative design despite the fact that many researchers indicate that ignoring soil-structure interaction may lead to underestimation of seismic response. The current paper aims to investigate the effect of SSI on the nonlinear seismic behavior of 9-span continuous bridge supported on pile foundation penetrating sandy soils. Three types of soils were investigated representing medium to stiff sandy soil. Both pushover analysis and nonlinear time history incremental dynamic analysis are carried out using Opensees to investigate the effect of SSI on the seismic response parameters (namely, fundamental period, pushover curves, foundation rigid body motions, global ductility capacity and demand, and maximum drift ratio) of the bridge and to compare it to fixed base assumption (i.e., SSI ignored). The results indicate that although SSI increases the flexibility of the structure (accordingly increasing fundamental period), the seismic demand of the bridge increases. This increase is more pronounced as the soil becomes softer.
Keywords: Incremental dynamic analysis, Inelastic seismic demand, Pushover analysis, Sand soil, Soil-structure-interaction.