Cyclic Loading Testing of U-Shaped Steel-Encased Beam-End Connection with Prefabricated Reinforced Concrete Beams

Abstract

The structural behaviour of beam-end connections between concrete-filled steel tube (CFST) columns and prefabricated reinforced concrete beams (PRC) is of great importance to CFST double-column pier systems. This paper proposes a U-shaped steel encased beam-end connection (SEBC) between square CFST column and PRC beam, in which the CFST column with U-shaped steel encasement and PRC beam are fabricated in the factory and assembled on site, a small amount of infilled concrete is cast into the steel encasement to enable the square CFST column and the PRC beam work integrally. A total of seven cyclic tests were conducted to investigate the hysteresis behaviour of SEBC in terms of bending resistance, ductility, stiffness degradation, and energy dissipation capacity. Two typical failure modes are identified in the tests: i) bending failure of the PRC beam, i.e. Mode BF, and ii) interfacial shear failure between the steel encasement and the infilled concrete, i.e. Mode SF. It is found that specimens with Mode BF exhibit excellent bending resistances and energy dissipation capacities. Based on the test results, load transfer mechanisms within the connections are identified, and design recommendations are proposed for rational design of the beam-end connections.

Keywords: beam-end connection, U-shaped steel encasement, hysteresis behaviour, prefabricated reinforced concrete beam, Energy dissipation capacity