Study on compressive behavior of high‐strength ceramic granular lightweight aggregate concrete confined with both spiral stirrups and <scp>CFRP</scp> under axial compression loads

Abstract In this paper, 24 high‐strength lightweight concrete columns confined with both spiral stirrups and CFRP cloth were tested under axial compression loads to explore the compression behavior of confined high‐strength lightweight concrete. The investigated parameters included the volumetric ratio of stirrups, the thickness of CFRP, and the compressive strength of concrete. The results showed that the failure modes of specimens confined with stirrups can be divided into shear failure mode in low stirrups volumetric ratio and the expansion failure mode in high stirrups volumetric ratio, while specimens confined with both stirrups and CFRP were in expansion failure. The axial stress‐axial strain curves of concrete only confined with stirrups and concrete confined with both stirrups and CFRP can be divided into elastic stage, elastic‐to‐plastic stage, axial stress sharply declined stage, and axial stress gradually declined stage. The concrete strength had the negative effects on the peak stress ratio, peak strain ratio, and ductility index on confined concrete, while stirrups volumetric ratio and CFRP thickness had positive influence on the strength and ductility of confined concrete. Furthermore, Wu model was suitable for evaluating the peak stress of confined concrete with high lateral confinement. The proposed models developed in this paper for evaluating the peak stress and peak strain of confined high‐strength lightweight concrete had high prediction performance. Moreover, the relationships between the ductility index of confined high‐strength lightweight concrete and the effective lateral confinement of confining materials were established. The low limitation for the lateral confinement of confining material was determined.