Seismic behavior of exterior beam-column connections with high-strength materials and steel fibers

Full-scale experiments on three reinforced concrete (RC) beam-column connection subassemblies (two roof-exterior joints and one exterior joint with a continuous column) were conducted under quasi-static reversed cyclic loading. The subassemblies were designed and constructed following ACI 318 requirements and ACI 352 recommendations; an exception was made for certain parameters related to use of high-strength materials and/or steel fiber-reinforced concrete in special moment frames. The beam-column connections using high-strength steel and concrete exhibited satisfactory performance and withstood very large lateral drifts. Test results also demonstrated that the addition of steel fibers in a 1% volume fraction effectively allowed for a 30% reduction in column/ joint confining reinforcement. An evaluation of the test results further leads to the conclusion that current limits on the allowable strength of longitudinal and transverse reinforcement in RC connections of special moment frames can be expanded to include higher-strength material grades.