Dynamic Characteristics and Lateral-Torsional Vibration Response of SRC Frame With Special-Shaped Columns

Abstract

This study investigates the seismic performance and torsional responses of a 5-floor steel-reinforced concrete (SRC) structure with special-shaped columns. A three-dimensional seismic simulation shaking table test was conducted to analyze the dynamic coupling effects in lateral, torsional, and lateral-torsional directions. The results reveal distinct torsion coupling phenomena in the Y- and X-directions during high-order vibration modes. As seismic intensity increases, the free vibration frequency of the frame structure decreases steadily, while the acceleration amplification coefficient shows a tendency toward reduction. The internal damage to the structure and energy dissipation increase with higher seismic intensities. Notably, when subjected to an 0.80 g PHGA earthquake intensity level, the maximum inter-storey drift ratio attributed to lateral-torsional coupling exceeds the required elastic–plastic inter-storey drift ratio threshold (1/39). Additionally, the damage index of the frame structure, calculated using a deformation and energy parameter model, is 0.56. A novel mathematical model for lateral-torsional coupled vibration has been developed based on experimental data. The findings indicate that accidental eccentric torsion has minimal impact on the seismic performance of the model structure, with an accidental relative eccentric distance less than 0.1. These results demonstrate superior seismic performance and high torsional deformation capacity of the special-shaped column design, offering valuable insights for improving earthquake-resistant structural designs in modern buildings.