Seismic behavior of interior concretebeam-column joints with non-seismic and limited seismic detailing

Reinforced concrete structures are very common in a region of low to moderate seismicity, and are the predominant structural system in Singapore and Malaysia. Recent post-earthquake investigations indicated that extensive damage occurred as a result of excessive shear deformation and severe strength degradation of the beamcolumn joints in non-seismically detailed frames, thus leading to full collapse of structures. The BS 8110 code used in Singapore and Malaysia does not specify any provisions for seismic design or detailing of reinforced concrete structures. Therefore, it is of great concern that the strength, ductility, and energy dissipation capacity of these structures may not be adequate to sustain earthquake-induced loads in regions of low to moderate seismicity. The need for evaluating and improving detailing of existing structures is obvious. Two full-scale reinforced concrete interior beam-column joints with non-seismic detailing and limited seismic detailing were designed and tested to investigate the seismic behavior of the joints at Nanyang Technological University, Singapore. The main variables in the test specimens included the amount of joint transverse reinforcement, the lap splice details for column reinforcement, and the transverse reinforcement in the beams and columns. Quasi-static cyclic loading simulating earthquake actions was applied. The non-seismically detailed specimens failed at the low displacement ductility level, while the limited seismically specimens reached the limited displacement ductility level. It was demonstrated that even limited seismic detailing could improve the seismic behavior of the joints. Column main bars lap spliced within plastic hinge regions were detrimental. The beams and columns were not severely damaged while shear failure formed in the joints. Implications of the experimental and analytical evidence were discussed and design recommendations of beam-column joints were made.Bachelor of Engineering (Civil