Seismic Behavior of Short Coupling Beams with Different Reinforcement Layouts

An experimental investigation on the seismic behavior of reinforced concrete coupling beams is presented. The reinforcement layout and the loading history were the main variables of the tests. Fifteen short coupling beams with four different reinforcement arrangements were tested. They were subjected to monotonic and cyclic loading by a suitable experimental setup. All specimens were characterized by a shear span-depth ratio of 0.75. The reinforcement layouts consisted of: a classical scheme (a); diagonal scheme without confining ties (b1); diagonal scheme with confining ties (b2); and inclined bars to form a rhombic configuration (c). Concrete compressive strengths of the specimens varied from 40 to 54 MPa. Test results showed that the beams with diagonal or rhombic reinforcement layouts behaved better than beams with longitudinal arrangement of the steel bars. These results were produced by the different resisting truss mechanisms that were developed in the coupling beams after the first cracking. The differences in energy dissipation were negligible between the diagonal and rhombic layouts. The rhombic arrangement, however, was more advantageous in terms of rotational ductility capacity, and decay in strength and stiffness of the beams. Moreover, cyclic tests demonstrated that the behavior of the rhombic layout was less affected by the different loading histories.