Experimental evaluation of lightweight aggregate concrete beam-column joints with different strengths and reinforcement ratios

摘要

The performance of beam-column joints significantly affects the overall behavior of reinforced concrete (RC) frames and, in some cases, can reduce the load carrying capacity and increase the lateral displacements of the frames. Also, when simultaneously small cross sections and a high number of rebar are used, the reinforcement detailing and the casting of concrete can be a difficult task. Despite this, there is a lack of attention for design and detailing the RC joints. The experimental study herein presented is focused on the behavior of exterior beam-column joints of lightweight aggregate concrete (LWAC) under monotonic loads. The study aims to evaluate the influence of rebar detailing of LWAC strength and of reinforcement ratio on the joints' behavior. Five specimens, combining different reinforcement ratios and concrete strengths, were properly monitored and tested. The strength capacity, deformability, and stiffness of the LWAC joints were analyzed. The experimental results enhance the importance of an adequate reinforcement detailing of the beam-column joint, because incorrect detailing decreases considerably the load capacity. Based on the results, it is highly recommended to use larger columns than beams, to reduce the cracking and increase the joint's stiffness.