Cyclic Experiments on Concrete-encased CFST wall-RC Coupling Beam Joints with Non-through-core Anchorages

Abstract

ABSTRACT In this study, a new type of non-through-core anchorage is proposed to anchor longitudinal reinforcing bars (rebar) in reinforced concrete (RC) coupling beams into concrete-encased, concrete-filled, steel tube (CFST) composite shear walls. The cyclic behaviour and anchorage performance of the coupling beams is investigated. The concrete-encased CFST wall consists of two boundary CFST components and an outer RC component. U-shaped reinforcing bars are embedded in the concrete-encased CFST wall to anchor the longitudinal rebars into the RC coupling beams. Cyclic loading tests are conducted on six wall-beam joint specimens, for a constant axial load on the wall and a cyclic load on the coupling beam. The test parameters include the rebar anchorage construction, the concrete strength, and the span-depth ratio of the RC coupling beam. The test results are used to perform a detailed analysis of the failure modes, hysteretic responses, strains, skeleton curves, bearing capacities, ductilities, and energy dissipation capacity. The specimens exhibit highly stable hysteresis behaviour and large inelastic rotation with a high damage tolerance. Slippage is observed after the appearance of diagonal shear cracks, which lead to clear pinched hysteresis behaviour. Interestingly, the buckled longitudinal rebars develop strain later than the directly anchored longitudinal rebars. The proposed anchorage construction can accommodate the largest residual deformation and has a reliable anchoring capacity.