Seismic Performance of a Novel Precast Beam-Column Joint Using Shape Memory Alloy Fibers-Reinforced Engineered Cementitious Composites

A novel precast beam–column joint using shape memory alloy fibers-reinforced engineered cementitious composites (SMA-ECC) was proposed in this study to achieve self-repairing of cracks and internal damage after an earthquake. Three large-scale beam–column joints were tested under displacement reversals, including one monolithically cast conventional concrete joint, one engineered cementitious composites (ECC) reinforced precast concrete joint, and one SMA-ECC reinforced precast concrete joint. Failure mode, crack pattern, hysteretic behavior, stiffness degradation, displacement ductility, and energy dissipation capacity were compared and evaluated through a cyclic loading test. The test results showed that the ECC-based (ECC, SMA-ECC) precast joints have equivalent seismic properties to the monolithically cast concrete joint. ECC-based joints enhanced the ductility and energy dissipation capacity of the joint and, remarkably, reduced crack width. The SMA-ECC reinforced joint also exhibited instant self-healing in terms of the closure of small cracks after unloading. The self-healing performance was further evaluated through ultrasonic pulse tests, with the results showing that the use of SMA-ECC material was efficient in reducing the internal damage of beam–column joints after an earthquake.

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