Effects of continuity plate and transverse reinforcement on cyclic behavior of SRC moment connections

Abstract

Two exterior moment connections with a steel-encased reinforced concrete (SRC) column and a steel beam were tested to evaluate the cyclic performance. Continuity plates were eliminated in the first specimen, and about 60% of the transverse reinforcement as specified in the ACI 318 was used in the connection region. Two steel doubler plates offsetting from the column web were used to enhance the shear resistance of the connection. The second specimen used a steel jacket to confine the concrete in the connection region and continuity plates were extended from the steel column to the steel jacket to mobilize the shear resistance of the latter; no transverse reinforcement was used. Full-scale test results showed that both specimens were able to reach an interstory drift ratio in excess of 4%. An analytical model was developed for the concrete shear force transfer mechanism in the connection of the second specimen. This study showed that: (1) using either doubler plates or jacket plates was effective to enhance the shear capacity in the connection, (2) concrete shear resistance degraded before the maximum applied load was reached in the first specimen, (3) the concrete was mobilized to resist shear in the second specimen, and (4) transverse reinforcement as required by the ACI 318 (1995) can be relaxed as long as another shear-resisting mechanism such as doubler plates or jacket plates is provided.