Review of studies on concrete columns confined by lateral reinforcement under axial compression and lateral cyclic loading

The restraint of lateral reinforcement can effectively improve the bearing capacity and deformation capacity of confined concrete columns. Generally, the behavior of confined concrete column under axial compression and lateral cyclic loading is a complex process and has been the subject of numerous studies dating from last century. This paper presents a review to summarize and discuss the investigations of concrete columns confined by lateral reinforcements under axial compression and lateral cyclic loading with the aim of obtaining a clear understanding on the mechanism and performance of confined concrete column. In this paper, a test database of confined concrete columns under axial compression and lateral cyclic loading is established, presented, and evaluated. The detailed provisions of confined concrete columns from current codes are concluded and it is found that these codes neglect the beneficial effect of lateral reinforcement on shear bearing capacity of confined concrete columns under lateral cyclic loading. Additionally, the stress-strain models and development of lateral reinforcement strain/stress in confined concrete columns under axial compression are mainly presented and discussed. Moreover, theoretical and experimental studies on seismic behavior of confined concrete columns are evaluated, including compression-flexure calculation, shear bearing capacity, ductility, energy dissipation capacity, and other detailed requirements. Furthermore, main influential factors of confined concrete columns under axial compression and lateral cyclic loading are discussed, respectively and it is founded that the synergy work of longitudinal and lateral reinforcement, and the deformation coordinated relationship between lateral reinforcement and core concrete significantly affect the bearing capacity and deformation capacity of confined concrete columns. Therefore, further studies are suggested to optimize and quantify the strength grade combination relationship between lateral reinforcement, longitudinal reinforcement, and concrete to achieve economical design and construction.