Design of raft-pile foundation using combined optimization and finite element approach

This paper describes the application of a structural optimization approach combined with the finite element method for the optimal design of a raft-pi le foundation system. The analysis takes into account the non-linear behavi our of the soil medium and the piles. For the optimization process, the sen sitivity analysis is carried out using the approximate semi-analytical meth od while the constraint approximation is obtained from the combination of e xtended Bi-point and Lagrangian polynomial approximation methods. The objec tive function of the problem is the cost of the foundation. The design vari ables are the raft thickness, cross-section, length and number of piles. Th e maximum displacement and differential displacement are selected as the co nstraints. The proposed method is shown to achieve an optimum design of raf t-pile foundation efficiently and accurately. Copyright (C) 1999 John Wiley & Sons, Ltd.