UCLA Civil & Environmental Engineering Department

C&EE 200 Section 1 Seminar

Structural, Geotechnical and Civil Engineering Materials

Suitability of Numerical Modelling Approach of an Integral Bridge for Strengthening of RC Pile Foundation Using SSI

Dr. Sreya Dhar

Indian Institute of Technology, Guwahati

Abstract: Integral Abutment Bridges (IABs) have become widely popular in the recent years due to the absence of bearings at the junction of bridge deck and bridge abutment. In the present study, a multi-span RC integral bridge on RC pile foundation is first modelled using Open-Sees, with stratified foundation soil. For modelling Soil-Structure Interaction (SSI), two approaches are implemented separately, namely (a) soil domain approach in which the soil is modelled as a continuum, and (b) spring-dashpot approach in which the lateral strength and stiffness of the soil are modelled considering Beam on Dynamic Winkler Foundation concept. Under the selected site-specific ground motions, nonlinear time history analyses are carried out for different models with changes in boundary conditions at the bottom of the piers, presence or absence of backfill soil and the two different SSI modelling approaches. In the second part of the study, the overall length of the same integral bridge is changed and nonlinear time history analysis is carried out under site specific ground motions in different types of foundation soil. Subsequently, one of the retrofitting methods for pile foundation, i.e., through installation of new piles encased in jet grout, is implemented on the pile groups below abutments and the piers in two separate stages. For certain soils, the response of the bridge gets significantly improved through reduction of nonlinear behaviour of the components, after applying the retrofitting method. In a summary, the present thesis tends to provide insight into the seismic behaviour of an integral bridge with RC pile foundation from the aspects of different numerical modelling approaches, influence of overall length and improvement in the response of pile foundation through encasement method of retrofitting.

Where: A18 Haines Hall

When: 12:00 – 12:50 PM, Wednesday, March 6, 2019

Bio: Sreya Dhar received her Ph.D. (2018) in Civil Engineering from Indian Institute of Technology Guwahati. She was an Erasmus Mundus Scholar (2014‒2017) in Dept. of Civil and Environmental Engineering of Politecnico Di Milano, Italy under the supervision of Prof. Roberto Paolucci and Prof. Lorenza Petrini. She completed her Bachelor of Engineering (2012) from Jadavpur University, India.