Abstract: This study investigated pile-cap-soil system considering different connection details in four pseudo-static seismic tests using a 1.2 m×1.2 m×1.2m mini-soil box. The failure modes, hysteretic performance, stiffness degradation, moment of pile and soil pressure were observed. Effects of the different pile-cap connections on the seismic performance were studied. The research shows that the different connections obviously influence the pattern and degree of failure of the pile head, the energy dissipation of the system, the level of ultimate bearing capacity, and the distribution of pile bending moment. However, the distribution and magnitude of soil pressures on cap sides and pile are not influenced by the connection types. For common connections, it is optimum that pile head is directly embedded in pile cap by 0.5D. When the strengthen ring connection is adopted, the restraint effect of the strengthen ring connection is roughly the same as that of common connections (embedded depth is 1.0D). Obviously, the construction of the strengthen ring connection is complicated, the restraint effect and damage form of the strengthen ring connection are related to the section, the strength of concrete and reinforcement of strengthen ring. The further works will be needed to analyze these parameters.

Key words: pile-cap-soil system, soil box, quasi-static test, failure mechanism, constraint degree