Seismic performance and coupling mechanism of modular concrete shear wall structures under multi-directional excitation

Abstract

To reveal the seismic coupling mechanism of modular integrated construction (MiC) concrete shear wall structures under multi-directional excitation, this paper adopts shaking table test data of a full-scale three-storey typical MiC concrete shear wall unit subjected to unidirectional, bidirectional, and triaxial seismic inputs. The dynamic responses, deformation characteristics, interfacial mechanical behavior, and hysteretic energy evolution of the structure are systematically analyzed to explore the influence mechanism of multi-directional excitation on the seismic performance of modular concrete shear wall structures. The test results indicate that bidirectional excitation amplifies the X-direction inter-storey drift, with 62.96% of cases presenting larger drift ratios than unidirectional X excitation. Compared with bidirectional excitation, triaxial coupling has a limited enhancement on the Y-direction interfacial opening deformation. Multi-directional seismic inputs tend to induce structural torsion, and amplified torsional responses occur in 88.89% of X-direction multi-directional loading cases. At the seismic level of PGA = 0.265 g, the X-direction hysteretic energy dissipation increases from 73.18 kJ under unidirectional loading to 103.55 kJ under triaxial loading. The structural effective stiffness gradually degrades and the hysteretic performance deteriorates continuously during the loading process. Compared with unidirectional seismic action, multi-directional coupling significantly increases the relative slip deformation between modules. This study clarifies the synergistic evolution mechanism of interfacial deformation and global structural response under multi-directional seismic coupling, providing experimental references for the seismic design of modular concrete shear wall structures in high-seismicity regions.