New configuration of transverse reinforcement for improved seismic resistance of rectangular RC columns: concept and axial compressive behavior

Columns are considered to be critical members of moment-resisting structural systems. In seismically active regions, it is important to improve the ductile deformation capacity and energy dissipation capacity of columns so that the entire structure can endure severe ground motion and dissipate a considerable amount of seismic energy. Against this background, this paper presents the idea of a new transverse reinforcement configuration (TRC) for improved seismic performance of rectangular (including square) reinforced concrete (RC) columns. The novel features of the new TRC compared to conventional TRCs using rectangular hoops and cross ties mainly include the use of additional small circular spirals near the column ends (i.e., potential plastic hinge regions). Such a simple change can significantly enhance the performance of RC columns without complicating their construction. In this paper, the rationale for the new TRC together with its expected advantages is first explained. A series of axial compression tests on RC columns with the new TRC are then presented to demonstrate some of the expected advantages. The test results confirmed that the concrete is very effectively confined by the new TRC, leading to significant enhancements in both the load capacity and ductility of RC columns.