A pilot experimental study on seismic behavior of recycled aggregate concrete columns after freeze-thaw cycles

The deterioration of concrete structures due to freeze-thaw cycles is a common problem in cold regions. In this paper, the seismic behavior of recycled aggregate concrete (RAC) columns after freeze-thaw cycles (FTCs) was investigated. RAC columns with three recycled coarse aggregate (RCA) replacement ratios (0, 50% and 100%) and subjected to different FTCs (0, 40 and 80) were tested under constant axial and reversed cyclic lateral loading, The seismic performance was analyzed in terms of various factors: failure patterns, load-displacement relationship, ductility, energy dissipation and stiffness degradation. The deformation in the plastic hinge region was also discussed. The experimental results indicated that all specimens failed in a flexure-dominated mode. Compared with conventional concrete columns, columns with higher RCA replacement ratios had lower load-carrying capacity and poor ductility after FTCs due to poor frost resistance. The equivalent viscous damping ratio increased slightly at the same displacement level for RAC columns due to a larger residual plastic displacement. The initial stiffness was more sensitive to FTCs compared with the degradation rate of stiffness. FTCs and RCA replacement ratio had little effect on the contributions of the flexural, shear and slip deformations to the total lateral deformation. (C) 2017 Elsevier Ltd. All rights reserved.