Experimental research and finite element analysis on seismic behavior of square reinforced concrete columns with four interlocking spirals

The seismic performance of square reinforced concrete columns confined by an innovative transverse reinforcement configuration composed of four interlocking spirals and outer square stirrups were investigated experimentally and numerically. Five composite specimens were tested under quasi-static reverse cyclic loading. The experimental results indicated that compared with conventional single spiral reinforced square composite column (SSRSCC) the newly developed interlocking multi-spiral reinforced square composite column (IMSRSCC) even with a slightly lower volumetric confinement ratio exhibited superior seismic performance in ultimate bearing capacity, energy dissipation and delaying the degradation of strength and stiffness. Moreover, a detailed three-dimensional finite element model considering the bond-slip behavior between concrete and steel reinforcement was developed and validated through a comparison with experimental results. The stress development and confining mechanism of transverse reinforcement of IMSRSCC was explored and the effects of the main design parameters on the seismic performance of IMSRSCC were also discussed through parametric studies.