Experimental and numerical investigation on seismic performance of S-RC-SRC composite joint

Abstract The seismic performance of H-shaped steel upper column-RC beam-SRC lower column joint (S-RC-SRC composite joint) was investigated experimentally and numerically. The axial compression ratio n and size of H-shaped steel was studied in the test. The low-frequency cyclic loading tests were performed on four S-RC-SRC composite joints. The test results showed that the concrete in the connection zone was severely damaged. On basis of strain analysis and experimental observations, the flexural failure mode at the oblique section in connection zone was proposed. The relatively plump but pinched hysteretic curves indicated that S-RC-SRC composite joint possessed considerable energy dissipation capacity, with peak h eq of 0.192–0.208 and asymmetrical ductility coefficient ( μ + ‾  = 7.08 and μ − ‾  = 3.03). The strength and stiffness degradation were significant and asymmetrical in different loading directions. Experimentally-validated finite element method was applied to simulate the S-RC-SRC composite joint via ABAQUS. The parameter study showed that: the impact of axial compression ratio should be considered in two stages (low and high), under the low axial compression (0.2–0.35) hardly affected the hysteretic behavior but high axial compression (0.6–0.8) would cause distinguished failure mode; the enlargement of steel size could reduce the ultimate bearing capacity slightly. A theoretical method for evaluating the flexural bearing capacity S-RC-SRC composite joint was proposed and proved to be applicable with the maximum deviation of 3.5%.