Elastic-plastic torsional response of L-shaped frames under earthquake wave passage excitation with varying low-frequency content

This study focuses on L-shaped frame structures and utilizes nonlinear time-history analysis to evaluate how of seismic waves with varying low-frequency content affect the elastic-plastic torsional response during rare earthquakes. Five L-shaped frame models were developed using ABAQUS, with length-to-width ratios (L/B=) of 1:1, 1.5:1, 2:1, 2.5:1, and 3:1. By comparing peak shear forces and bending moments at the tops of corner columns in the direction of excitation under earthquake wave passage excitations, this research highlights the impact of low-frequency content on wave passage effect. Findings show that when seismic waves contain sufficient low-frequency content, wave passage effect occurs in wave-facing outer corner columns, whereas inner corner columns do not. The last-arriving outer corner columns, however, displayed no consistent pattern. With the rise of the L/B ratio (when L/B = 3), the peak shear force and bending moment of the wave-facing outer corner columns go up by 13.8% and 7.1%, respectively. The last-arriving outer corner columns encounter up to an 11.1% increases in peak shear force and 10% in peak bending moment. When the seismic waves lack sufficient low-frequency content, the corner columns of the L-shaped frame structure are less likely to experience wave passage effect.