Development of plastic hinges of pile groups subjected to lateral pushover

Abstract

The performance of existing pile groups and multiple pile group systems would be critical in ensuring the acceptable performance of the associated structures under the ever-increasing seismic hazard. It is argued that this could be assessed partly by understanding the development of plastic hinges in these pile group systems. This paper is to examine the development sequence of plastic hinges in pile groups and multiple pile group systems under lateral pushover, in different geotechnical conditions and pile types. An emphasis is put first on the spatial sequence of the plastic hinge development and second on the overall sequence of the development. A series of 3D numerical analyses is performed. The plastic hinges for single pile groups start to develop at pile head level, from perimeter piles and to center pile. For multiple pile group systems, the hinges start to develop in perimeter piles of the outer pile caps and to continue with firstly outer pile caps and subsequently the center pile cap. The plastic hinges at depths only appear to develop after plastic hinges at pile head level develop in all piles, and they develop in a similar pattern. Based on these findings, it is argued that pile retrofitting or repairing in pile groups would be possible, and therefore the performance of repaired damaged piles is briefly reported. In addition, the consequences of the plastic hinge development to the overall system load-displacement performance are discussed.