THEORETICAL STUDY OF UNIAXIAL FLEXURAL BEHAVIOR OF ULTRA HIGHPERFORMANCE REINFORCED CONCRETE BEAMS

Ultra high-performance concrete (UHPC) is an advanced cementitious composite consisting of a dense high strength matrix and fibers. The use of UHPC is growing worldwide owing to its high performance so leading to be employed in a wide range of practical applications like nuclear waste containment structures, high rise structures, long span bridges and thin shells. Studies on UHPC concentrated on special concrete materials with characteristics that differ from those of normal strength concrete at the material level. However, a few researches are available on the uniaxial flexural capacity of UHPC beams at the structural level that can predict the overall performance. This paper provides theoretical study for structural behavior of UHPC beams with different parameters. Parameters are: reinforcement ratio, concrete compressive strength, eccentricity ratio (e/t) and concrete cover. Eighteen finite element models were developed and analyzed in ANSYS software to investigate the effect of mentioned parameters on uniaxial flexural behavior of UHPC simple beams. The results showed that increasing the reinforcement ratio from 0.3 to 3 % led to increase in flexure capacity by 541 % and stiffness by 173 %. Increasing the concrete compressive strength from 115 to 215 MPa led to increase in the stiffness by 9.32 %. While, the flexure capacity wasn't affected. Increasing the eccentricity ratio (e/t) from 0.50 to ∞ led to decrease in flexure capacity by 49.7 % and stiffness by 49.8 %. Increasing the concrete cover from 30 to 70 mm led to decrease in flexure capacity by 17.2 % and stiffness by 30.6 %. The FEM and results of this study provide valuable data that can be used in future studies on the development of computational models of uniaxial flexural behavior of UHPC.