Seismic performance of code-designed fiber reinforced concrete joints

An experimental investigation is presented on the use of steel fiber reinforced concrete to provide ductility in beam-to-column joints during earthquake excitation. Four full-scale exterior beam-column joints, part of a prototype building designed according to the National Building Code of Canada, were tested under cyclic reverse loading. The first specimen was made of normal concrete but ignored all the special seismic recommendations related to the spacing of lateral reinforcement in the beams, columns, and joints. The second specimen was also made of normal concrete and incorporated full seismic details. The third and fourth specimens were similar to the first one but used steel fiber reinforced concrete in the joint region. Experimental results indicated that fiber reinforced concrete is an appealing alternative to conventional confining reinforcement. Steel fibers bridging across cracks in the concrete mix increase the joint shear strength and can diminishrequirements for closely spaced ties. The performance of a joint is closely related to the volume content and aspect ratio of the fibers.