Experimental study on seismic performance of prestressed concrete solid square piles

Abstract

Prestressed concrete solid square (PCSS) piles exhibit superior lateral bearing capacity and durability compared to pretensioned spun concrete pipe piles, and are more suitable for pile foundation engineering in high-intensity seismic regions and corrosive environments. There is still a lack of research on the seismic performances of the pile body of PCSS piles. This paper presents an experimental study and the associated theoretical and finite element (FE) analyses on the seismic performance of PCSS piles. Three full-scale PCSS pile specimens were tested under lateral cyclic loads with various axial force ratios, and the results are analyzed. Following the tests, a theoretical calculation method is proposed for the bearing capacity of PCSS piles. A FE model for PCSS pile specimens is established and validated against the test observations. Based on this model, a parametric analysis is then conducted. The results show that the PCSS pile specimens all exhibit typical flexural failure. Under a low axial force ratio, the failure mode of PCSS pile specimen is governed by the tensile rupture of prestressing tendons. Under a high axial force ratio, the failure is influenced by the crushing of cover concrete, while the concrete in the core zone remains intact, and there is no outward buckling of prestressing tendons and no rupture of stirrups. Increasing the prestressing tendon ratio can simultaneously improve the bearing and deformation capacity under a lower axial force. Under higher axial force ratios, however, increasing the prestressing tendon ratio or concrete strength can improve the bearing capacity but lead to a decline in deformation capacity. Compared to pretensioned spun high-strength concrete (PHC) piles, PCSS piles exhibit better seismic behavior on aspects of deformation capacity and ductility.