Studies On The Behavior Of High-strength Concrete Columns With High-strength Transverse Reinforcement Under Concentric Compression

The use of high-strength concrete has become popular in the field of civil engineering due to the workability, strength, impermeability and durability of the high-strength concrete. The brittleness of high strength concrete has a significant impact on the ductility and the capacity of the energy dissipation of concrete column. The transverse reinforcement is too close to construct through use of normal strength transverse reinforcement to satisfy the ductility of the high-strength concrete columns. At the same time, it is very expensive. So it limits the use of high-strength concrete. It has become an important topic to obtain ductile behavior in high-strength concrete columns through proper confinement with high-strength transverse reinforcement. It is a new solution to spread the use of high-strength concrete if using the high-strength transverse reinforcement instead of normal-strength transverse reinforcement to confine the high-strength concrete. However, studies about behavior of high-strength concrete columns with high-strength transverse reinforcement under concentric compression are scarce in China. In this paper, a test program on behavior of high-strength concrete columns with high-strength transverse reinforcement under concentric compression is presented. The detail works are summarized as follows:(1) Systematically reviewing the research progress in home and abroad on the behavior of high-strength concrete columns with high-strength transverse reinforcement under concentric compression.(2) The experimental phase of this investigation consists of twenty six confined columns and six unconfined columns subjected to concentric loading conditions to investigate the failure modes, stress-strain curves and the ductility of the high-strength concrete columns. It is found that the key variables that have significant effects on the ductility and strength of the high-strength concrete columns are the concrete compressive strength, the volumetric ratio of transverse reinforcement, the tie yield strength, the longitudinal reinforcement ratio. The results show that it is considered possible to improve strength and ductile behavior of the high-strength concrete columns through use of high strength transverse reinforcement instead of normal strength transverse reinforcement.(3) A comprehensive study of the experimental results for HSC columns is undertaken. Then, design equations of the strength and ductility of the confined concrete are proposed based on regression analysis. While, a mathematical model is developed to express the stress-strain relationship of high-strength concrete confined by transverse reinforcement. It has been verified against data obtained from column test under concentric load.(4) This thesis summarizes the novel ideas and raises some problems for future studies.