Experimental investigation on seismic behavior of eccentric RC beams with different reinforcement configurations

In reinforced concrete buildings, the seismic behavior of RC beams with flush outside faces of beams and columns has not been verified by experiments. In this study, four large reinforced concrete beam specimens are fabricated, and the experimental verification is carried out. The research results show that: (1) All the specimens (including three beam specimens with flush outside faces of beams and columns can have ultimate drift angles of up to 4% rad; (2) The lateral strength and seismic behavior of the specimen with concrete cover of 85 mm are no less than those of the benchmark specimen, so concrete cover thickness between 85 mm and 40 mm for RC beams should be acceptable; (3) The seismic behavior of the two specimens with the lateral U-shaped auxiliary transverse reinforcement and concrete cover of 85 mm is better than that of the benchmark specimen, but the crack width of the latter specimen is wider and the spallling degree of concrete cover is more serious. It is recommended to adopt the lateral U-shaped auxiliary transverse reinforcement whose two legs extend beyond half the width of the hoop with two auxiliary longitudinal reinforcements and the same spacing as the hoop in practice.