Seismic response of helical pile groups from shake table experiments: Fid-Bau Portal

Seismic response of helical pile groups from shake table experiments

Fayez, A.F. / El Naggar, M.H. / Cerato, A.B. / Elgamal, A.

Abstract This paper presents and discusses the measured responses of single and grouped helical piles to strong ground motions during a large-scale shake table testing program. The effects of earthquake characteristics (i.e., intensity and frequency content) on the seismic performance of single and grouped helical piles are evaluated from the measured responses. In addition, the performance characteristics of helical pile groups are discussed in terms of the interaction between piles within a group and the contributions of vertical and lateral stiffness of individual piles to the rocking stiffness and the overall capacity of the pile group. Furthermore, the effect of pile head connection to the pile cap (fixed or pinned) on the pile group's response is evaluated and the responses of fixed pile groups (2-bolts connection) and pinned pile groups (1-bolt connection) are compared. Finally, the behaviour of a single pile and a pile within a group is compared in terms of their normalized responses.

Highlights • Large-scale shake table testing of single and grouped helical piles subjected to different ground motions was conducted. • Responses of single piles increased exponentially with PGA, while a linear relation was observed for pile groups. • Resonance conditions significantly increased responses for both single and grouped helical piles. • Helices provided additional resistance and fixation to the piles, which resulted in an 80% contribution of rocking stiffness. • 1-bolt pile head connection provided fixation and should not be considered as pin connection.