ABSTRACT
An efficient method is presented for the analysis of buildings with grouped piles for seismic stiffness and strength design. A continuum model composed of a dynamic Winkler-type soil element and a pile is used to describe the dynamic behavior of the pile-soil system within a reasonable accuracy. The pile-group effect is considered by introducing the influence coefficients among piles which are defined for interstory drifts and pile-head bending moments. It is shown that, while the pile-group effect generally decreases the interstory drift of buildings, it may increase the bending moment at the head of piles in some cases. This fact implies that the procedure without the pile-group effect leads to the conservative design for superstructures and requires a modification of member design for piles. It is concluded that a detailed and efficient examination of the pile-group effect is absolutely necessary in the practical seismic design of buildings from the simultaneous viewpoints of stiffness and strength.
