Optimum percentage of steel fibres of HPFRCC for reduction of transverse reinforcement in beam–column joints

Abstract

Reinforcement congestion causes problems during construction, including improper concrete pouring and concrete vibration. In this study, the replacement of normal concrete by high-performance fibre-reinforced cementitious composites (HPFRCC) has been investigated in order to reduce the amount of transverse reinforcement and prevent reinforcement congestion in beam–column joints. Uniaxial compression and tension tests were used to determine the mechanical properties of HPFRCC materials. In order to investigate the effects of HPFRCC on improving and upgrading the joint strength, five half-scale exterior beam–column joint connections were tested under incremental cyclic lateral loading. The tested specimens consisted of two normal concrete control specimens with and without specific seismic details and three specimens of HPFRCC with different percentages of steel fibres. The cracking patterns, hysteresis behavior, bearing capacity, energy absorption and damping percentage of all test specimens were analysed and compared with the response of normal concrete specimens. Results show that the use of HPFRCC materials in the joint area improves seismic behavior and significantly increases load-bearing capacity, energy absorption and ductility. Moreover, it prevents the shear failure of the joint and the formation of the flexural plastic hinge in the beam.