Comprehensive equation of local bond stress between UHPC and reinforcing steel bars

Abstract

An experimental test was conducted to analyze the Local Bond Stress (LBS) between Ultra-High-Performance Concrete (UHPC) and reinforcing steel bars. The test included 144 specimens based on RILEM standards, using pullout tests. Reinforcing steel bars of 16 mm and 18 mm in diameter, nano-silica contents from 0% to 6.5% by weight of cement, conventional and thermal curing methods, and the bond lengths and concrete covers of db, 2db and 3db were the research parameters in this study. Moreover, sixteen experimentally tested and 39 non-tested specimens were modeled using ABAQUS by taking into account additional parameters such as bond length and concrete cover of 4db, and bar diameters of 12, 14, 16, 18 and 20 mm. The resulting proposal was a comprehensive LBS equation to calculate the local bond stress between reinforcing steel bars and UHPC. A fair comparison between the results confirmed that the values obtained from the proposed LBS equation were logically in good agreement with the experimental and numerical results.