Cyclic Behavior of Reinforced Concrete Columns with L-Shaped Ties

Abstract

In reinforced concrete columns, both constructability and structural safety should be considered in selecting the anchorage details of transverse reinforcement. For the simple installation of peripheral hoops, in this study, L-shaped ties were proposed to replace the conventional closed hoops with 135° hook anchorages. The L-ties can be easily installed from the side of columns by temporarily moving a longitudinal bar. Cyclic lateral loading tests were performed on five reinforced concrete columns to verify the effect of the L-ties on the shear resistance and buckling resistance of longitudinal bars after concrete cover spalling. The main test parameters included the types of transverse reinforcement, aspect ratio of columns, and straight extension of hooks. The test results demonstrated that the strength, deformation capacity, and energy dissipation of the columns using L-ties were comparable to those of columns using the conventional closed hoops because 135° hooks at both ends in the L-ties were anchored in the core concrete. The straight extension of the 135° hook anchorages with 6db provided a sufficient anchorage performance despite following concrete cover spalling. Furthermore, nonlinear behaviors of the columns were discussed by comparing the nonlinear modeling parameters specfied in current standards to evaluate postyield deformation capacities.