Seismic performance of predamaged RC columns strengthened with HPFL and BSP under combined loadings

Abstract

This paper presents an experimental investigation of the seismic behavior of coupling predamaged reinforced concrete (RC) columns strengthened with high-performance ferrocement laminate (HPFL) and bond steel plate (BSP) that are subjected to combined loadings. A total of four specimens were fabricated. After they were predamaged with corrosion and an earthquake environment, they were strengthened with HPFL and BSP, and then tested under four different combined loadings, separately, which are unidirectional compression, bending, and shear (CBS); bidirectional CBS; unidirectional compression, bending, shear, and torsion (CBST); and bidirectional CBST. Their seismic behavior, including failure mode, bearing capacity, ductility, energy dissipation, stiffness degradation, damage index and residual displacement, was analyzed. The results revealed that the coupling predamaged RC columns still had retrofit value and that the retrofitting method utilized in this paper was effective. After repairing with HPFL and BSP, the bearing capacity can be significantly improved especially for torsional specimens, which increased by more than 100%. Other seismic behavior like ductility coefficient, stiffness, and single cyclic energy dissipation can be recovered well. In addition, the horizontal eccentricity had a negative effect on the seismic behavior of specimens, while the negative effect was reduced after strengthening.