Shaking table test of a frame structure with phononic-like crystal polymer concrete seismic mitigation raft foundation

Abstract

This study introduces a novel base mitigation system leveraging the concept of metamaterials, which encapsulates metal spheres (scatterers) within a flexible wrapping layer and then embeds them in cement mortar (matrix). Such materials hold significant potential in applications including energy dissipation and seismic mitigation, explosion shielding, and impact resistance. However, the seismic mitigation performance of this materials in building structures remains to be investigated. A seismic mitigation raft foundation made of phononic-like crystal polymer concrete is proposed in this paper. To investigate the seismic mitigation mechanism of the novel raft foundation, two 1/5-scale reinforced concrete (RC) frame structures with four stories and two bays are subjected to shaking table tests, systematically analyzing structural responses and failure patterns under seismic excitation. Among them, one structure is equipped with a phononic-like crystal RC raft foundation (PC frame), while the other uses an ordinary concrete raft foundation (OC frame). This paper mainly summarizes the phenomena observed from the shaking table test, such as the evolution of damage, dynamic characteristics and seismic responses. Then, a seismic mitigation ratio is proposed as an evaluation index to assess the seismic mitigation effect of the phononic-like crystal polymer concrete raft foundation. The results reveal that the PC frame structure exhibits reduced structural damage and attenuated seismic responses compared to the OC frame structure, indicating that the significant seismic performance enhancement achieved through the implementation of the phononic-like crystal polymer concrete raft foundation. Furthermore, this innovative raft foundation demonstrates superior seismic mitigation performance, particularly when subjected to ground motions with more high-frequency components.