Seismic Behaviour of Exterior Reinforced Concrete Beam-Column Joints in High Performance Concrete Using Metakaolin and Partial Replacement with Quarry Dust

Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged; the beam-column joints, being the lateral and vertical load resisting members in reinforced concrete structures, are particularly vulnerable to failures during earthquakes. The existing reinforced concrete beam-column joints are not designed as per code IS13920:1993. Investigation of high performance concrete (HPC) joints with conventional concrete (CC) joints (exterior beam-column) was performed by comparing various reinforcement detailing schemes. Ten specimens were considered in this investigation and the results were compared: four specimens with CC (with and without seismic detailing), four specimens with HPC (with and without seismic detailing), and two specimens with HPC at confinement joint. The test was conducted for lateral load displacement, hysteresis loop, load ratio, percent of initial stiffness versus displacement curve, total energy dissipation, strain in beam main bars, and crack pattern. The results reveal that HPC with seismic detailing will be better compared with other reinforcements details under cyclic loading and reverse cyclic loading. 1. Introduction Earthquakes present a threat to public safety and welfare in a significant portion everywhere. We cannot stop earthquakes, but we can protect ourselves from them, as “earthquakes do not kill human beings, but the structures do.” The behaviour of reinforced concrete moment resisting frame structures in recent earthquakes all over the world has highlighted the consequences of poor performance of beam-column joints. Beam-column joints in a reinforced concrete moment resisting frame are crucial zones for transfer of loads effectively between the connecting elements (i.e., beams and columns) in the structure. In the analysis of reinforced concrete moment resisting frames, the joints are generally assumed as rigid. In Indian practice, the joint is usually neglected for specific design with attention being restricted to provision of sufficient anchorage for beam longitudinal reinforcement. This may be acceptable when the frame is not subjected to earthquake loads. The poor design practice of beam-column joints is compounded by the high demand imposed by the adjoining flexural members (beams and columns) in the event of mobilizing their inelastic capacities to dissipate seismic energy. For the past three decades, extensive research has been carried out on studying the behaviour of joints under seismic conditions through experimental and analytical studies. Various international codes