Seismic Behavior of Coupling Beams with Double Hooked Steel Fiber Reinforced Concrete

Presented By: Mohamed Altameemi, University of Wisconsin Madison
Current design practice for earthquake-resistant coupling beams includes the use of intricate diagonal and transverse reinforcement detailing intended to ensure adequate drift capacity when subjected to large shear reversals. Although proven through laboratory testing to result in adequate seismic behavior, the required reinforcement detailing is difficult, time-consuming and costly to construct. The addition of high-strength, double hooked steel fibers to the concrete is therefore experimentally investigated as a means to simplify reinforcement detailing in coupling beams by eliminating and reducing diagonal and confinement reinforcement, respectively. The experimental program includes the testing of twelve large-scale coupling beams under large displacement reversals. The main experimental parameters investigated are coupling beam aspect ratio (2.0, 2.25, or 3.0), fiber type, and fiber volume fraction (1.0 or 1.25%). Experimental results have shown that coupling beams with aspect ratio between 2.0 and 3.0 constructed with SFRC containing high-strength, double hooked steel fibers in either a 1.0 or 1.25% volume fraction and no diagonal reinforcement can achieve drifts exceeding 5% while subjected to a peak average shear stress of at least 8v(?f`?_c ) (psi).