Behaviour of ultra-high performance fibre reinforced concrete beam-column joint under cyclic loading

Abstract

Ultra-high performance fibre reinforced concrete (UHPFRC) has very high compressive strength up to 200 MPa and exhibits strain hardening effects under flexural loading. The bond strength between UHPFRC and steel reinforcement is much better than the normal strength concrete. Therefore, there is a potential to use UHPFRC material at the beam-column joint region to reduce the congestion of reinforcement as well as to improve the seismic resistance of the structure. In this pilot study, the beam column joints made of normal strength concrete and UHPFRC were tested under lateral cyclic loading up to failure using a 500 tonne capacity computer control servo hydraulic machine. The specimen with normal strength concrete failed at the joint region while the specimen with UHPFRC material failed due to yielding of the rebars in the beam sections near the column face and no obvious cracks were observed at the joint area. The specimens with UHPFRC as joint material exhibited higher initial lateral stiffness and achieved slightly higher ultimate load capacity than the specimen with normal strength concrete.