Application of high strength reinforcing bars in earthquake-resistant structure elements

Currently, design of reinforced concrete buildings is still dominated with normal strength reinforcing bars, not exceeding 420 MPa yield strength. Meanwhile, the use of higher strength reinforcing bars tend to increase due to some benefits in the construction, such as reducing the total weight of reinforcing bars and alleviating reinforcing bars congestions. In this study, reinforcing bars with yield strength of 520 MPa are utilized in the reinforced concrete beam-column joint. The objective is to study the seismic performance of reinforced concrete beam-column joints. A total of 3 interior beam-column joints, half-scaled specimens with different yield strengths and bar diameters was tested. One of the test specimens which was 16 mm diameter and had normal strength reinforcing bar. The other two specimens use high strength reinforcing bars, and have 16 mm and 19 mm diameter bars. Loading protocol of all the specimens is conformed with ACI 374.2. Dissipation energy and deformability of the joints is then compared. Normalized energy dissipation of the specimens with high strength reinforcing bars was slightly lower than that of the specimens with normal reinforcing bars. However, specimens with high strength reinforcing bars tend to have smaller deformability than that of the specimens with normal reinforcing bars.