Seismic performance of PHC pipe piles in layered soft soils

Considering the layered soft soils in Tianjin, a 2D numerical model for analyzing kinematic interaction of frame-pile-layered soils is established to ascertain the seismic performance of PHC pipe piles. The results reveal that the risky region of piles due to seismic load is likely to be at pile head or near the interface between the soft and stiff soil layers. Moreover, the magnitude of bending moment on the piles at such interface largely depends on the stiffness ratio of the adjacent layers. Besides, other important factors which influence the seismic performance of PHC pipe piles are highlighted, such as soil thickness, floors of frame, pile length and pile diameter. It is suggested that the thickness of soft soils and the soils above the piles and the piles diameter have important influence on the bending moment of the piles, while the floors of frame has little impact on them.