Seismic performance of short reinforced concrete columns with L-shaped ties under cyclic loading

Abstract

This study investigates the seismic performance of reinforced concrete (RC) columns with L-shaped ties, proposed as an alternative to conventional closed hoops with 135 degrees hook anchorages. The L-shaped ties are designed to enhance constructability by allowing lateral installation through temporary displacement of longitudinal bars. Cyclic lateral loading tests were performed on eight short RC columns to examine the effects of transverse reinforcement type, tie spacing, and axial load ratio on structural performance. The test results indicated that Lshaped ties provided shear resistance, deformation capacity, and energy dissipation comparable to conventional closed hoops. Closely spaced L-ties improved post-peak deformation capacity due to increased shear resistance. Columns subjected to high axial load ratios (N/Agfc'=0.35) exhibited shear-compression failure prior to longitudinal reinforcement yielding, whereas lower axial load ratios (N/Agfc'=0.138) allowed flexural yielding before shear failure. Nonlinear modeling parameters from ASCE 41-17 provided reliable predictions of the deformation capacity of columns with L-shaped ties. These findings demonstrate that L-shaped ties provide a practical and efficient solution for large RC columns or concrete-encased steel columns, particularly in applications where the installation of closed hoops is challenging and high axial loads are present.