Cyclic Behaviour Of Beam-Column Joints With Corbels Under In-Plane Lateral Loads

Corbels appearance in precast beam-column joints has a significant impact on the behaviour of the transition zone at the end of the beam which could help in delaying the yielding of the top reinforcement bars and increase the stiffness of the joint. The presence of corbels also released the development of unnecessary strain at the top of the internal reinforcement bars. Hence, the main objective of this paper is to access the emulative approach for beam-column joints with corbels in terms of structural behaviour for any seismic action through experimental work. Comparison of the experimental hysteresis loops (load versus displacement) and seismic performance for the three types of joints were made. Three full-scale sub-assemblages of corner, exterior and interior precast beam-column joints with corbel were designed using BS8110 Code of Practice. These three specimens were constructed and tested in a heavy structural laboratory under in-plane lateral cyclic loading. The corner, exterior and interior beam-column joints were tested starting from +/- 0.01% until 1.35% drift, +/- 1.00% drift and +/- 1.15% drift, respectively. This study found that the existence of corbels in precast joints can delay the yielding of the top reinforcement bars and increase the stiffness of the joint. However, the experimental result has proved that the corbel for corner beam-column joint was the weakest point of the joint based on the crack damaged at the corbel. On the other hand, the experimental work found that precast beam-column corner joint specimen exhibited 21.5% more ductile behaviour as compared to other two specimens. However, the ductility values for all specimens were recorded at less than 3, indicating that precast beam-column joint specimens were not able to take moderate to strong earthquake excitation.