Simplified Methodology for Stiffness Estimation of Double D Shaped Caisson Foundations
Foundation stiffness plays a crucial role in the stability analysis of structures to incorporate the Soil Structure Interaction (SSI) effects. Current design approaches of estimating foundation stiffness include advanced dynamic finite element, distributed spring approach, and lumped spring approach. The aim of this paper is to overview the different methods for computing the foundation stiffness and to check their applicability. This has been done by considering an example: Saraighat Bridge supported on double D shaped caisson foundation. Advanced three dimensional finite element analysis is performed to extract the stiffness (Lateral, rotational, and coupling) of double D foundations and the results are compared to the representative circular foundations. It has been concluded that the stiffness of foundation can be significantly affected by its geometry. Furthermore, the stiffness functions are utilized in computing the fundamental frequency of the bridge and also compared with the frequency obtained from different approaches. The frequency estimated using the present study matches satisfactorily well with the monitored data testifying the validation of the work.
The first author would like to thank the Commonwealth Scholarship Commission (CSC) for providing him the financial support (reference no: INCN-2016-214) enabling him to perform his research activities in the University of Surrey, United Kingdom. The funding received is fully acknowledged.
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