No abstract

No abstract

No abstract

Concrete circular columns are among the most common vertical load-bearing members in structural engineering. Because of the change of service loads or environmental factors, the strengthening of deteriorated members is often demanded to restore and maintain their performance. In view of the limitations of the traditional strengthening methods and the superior mechanical properties of the new material, ultra-high-performance concrete (UHPC), this study analyzed the stress–strain state of concrete circular columns confined by UHPC jackets under axial compression in the elastic stage. Since elastic analysis is the basis for the service limit state design, the elastic stress solution was derived through the theory of elasticity, and experimental verification of the effectiveness of the UHPC jackets in circular concrete columns was performed. Theoretical bases and references for practical strengthening works are provided.

This guide Ultra-high performance concrete shows great potential in the construction industry. However, the structural-level ductility of UHPC members has not been clearly established and is frequently subverted by the crack localization phenomenon. This paper presents an experimental investigation of the structural ductility of a total of twelve UHPC beams tested under flexure. The main variable parameters are the reinforcement ratio, ranging from low to high ratios, and the fibers volumetric ratio, selected as 0%, 1.5%, and 2.5%. The results revealed that 1.5% fiber content and a corresponding reinforcement ratio between 1.2 % -4.4% are generally adequate for generating sufficient ductility on a structural level, and further increasing the fiber content has a minimal enhancement to the ductility. Moreover, adding fibers is not only necessary to improve the ductility from the tension side, but also from the compression side as the fibers impose a slow and gradual crush of UHPC, thereby improving the ductility in the post-peak branch.