Theoretical analysis of dynamic performance of concrete-filled steel tube pile under vertical load

Abstract

The concrete-filled steel tube (CFST) pile is a type of composite pile that offers a preferable alternative to the traditional pile owing to its exceptional advantages. In this study, a new theoretical model is established to investigate the dynamic performance of the CFST pile under vertical load. The inner concrete column, outer steel tube and surrounding soil are modelled as axisymmetric elastic continua taking account of both the vertical and radial motions. The interface conditions between different materials and specific mathematical tools are then introduced to obtain the theoretical solution for the dynamic impedance of CFST piles. Existing solutions are involved in the verification of the obtained solution. Furthermore, combined with the defined soil resistance factor of the CFST pile, extensive parametric analysis is conducted to explore the impact of geometric and mechanical parameters of the CFST pile-soil system on its dynamic behavior under various working conditions. It is found that two cut-off frequencies exist during the axial vibration of the CFST pile within the low-frequency range and their characteristics are thoroughly investigated. The observations provide valuable guidance and enhanced interpretation for the dynamic analysis and design of CFST piles.