Shear behavior of ultra-high performance concrete

The application of ultra-high performance concrete (UHPC) as an alternative to conventional/normal concrete (NC) has grown rapidly in recent years. However, there is limited knowledge on its shear behavior, which is essential for developing design guidelines for structural applications. A detailed parametric study was conducted on 38 beam specimens, half of which were made of UHPC and the other half made of NC. To ensure applicability of findings, two types of UHPC mixes were used, a proprietary and a generic mix. Eighteen of the beams were prepared and tested in Tabriz, Iran, while the other 20 were made and tested in Miami, FL. Test parameters included type of concrete (UHPC and NC), shear span-to-depth ratio (0.8, 1.2, and 2.8), reinforcement ratio (2.2% to 7.8%) and reinforcement anchorage. All specimens had the same length but different cross sections. Test results proved UHPC specimens to have much higher shear strength and ductility than NC beams. Normalized shear and shear strength both increased for shorter shear spans and higher reinforcement ratios. The anchorage did not affect UHPC beams, while it improved ductility of NC beams. Theoretical shear strengths, as determined by RILEM equations for UHPC beams, proved very conservative, confirming the need for more accurate assessment of shear strength of UHPC. Published by Elsevier Ltd.