Seismic performance of semi-precast high-strength recycled aggregate concrete columns with high-strength reinforcement

Abstract

There is a growing interest in the development of precast structures. In this paper, a semi-precast high-strength recycled aggregate concrete (RAC) column with high-strength reinforcement was studied, which was consisted of cast-in-situ core concrete surrounded by a precast external shell. Six full-scale columns were fabricated and tested under cyclic lateral load, of which two were cast-in-situ columns and four were semi-precast columns. The penetration of shear reinforcement between precast external shell and cast-in-situ core column, core column diameter and axial load were the major design parameters. The test results showed that all specimens exhibited a good deformation capacity with an ultimate drift ratio greater than 3%. The semi-precast columns had comparable seismic performance with the cast-in-situ columns, indicating that the penetrating shear reinforcement and the core column diameter had little effect on the seismic performance. The core column diameter could be selected according to the practical engineering requirements. Increasing the axial load can significantly improve the lateral load-carrying capacity of the specimens, but would result in larger residual drift ratio, which was adverse to the repairability of the specimens. The flexural deformation and the deformation resulting from slippage of longitudinal reinforcement in the concrete foundation accounted for 50%–80% and 10%–20% of the lateral displacement, respectively, which should not be ignored in the deformation calculation; however, the shear deformation can be ignored. The optimized models applicable to calculate the F-Δ curves of semi-precast high-strength RAC columns with high-strength reinforcement were proposed. Parametric analysis based on the optimized models was carried out to develop N-M curves for various precast external shell or core column concrete strength, and core column diameters.