INVESTIGATION ON FLEXUREL CAPACITY OF RENINFORCED ULTRA HIGH PERFORMANCE CONCRETE BEAMS

4 span-depth ratio of 16 reinforced ultra-high-performance concrete beams were fabricated for the investigation of their flexural behavior and flexural capacity. The variable parameters studied in the test were steel fiber volume fraction and longitudinal reinforcement ratio. Testing results show that increasing steel fiber volume fraction from 3% to 5% could increase the resistance of cracking (cracking load increased by 6.0% to 11%). However, it had little effect on the ultimate load capacity (only increased 1.4%~2.5%). The failure modes of the beams with the longitudinal reinforcement ratio of 3.21% and 6.74% were classified as under-reinforced failure and limited over-reinforced failure respectively. Increasing the reinforcement ratio could enhance the flexural capacity of reinforced UHPC beams (increased by 34.9%~36.5%). A tentative flexural capacity calculation model of reinforced UHPC beams was proposed based on the section equilibrium condition, the assumption of plane section, the material constitutive relation of UHPC, and reinforcement. The calculation results of flexural capacity are found agreeing well with the experimental results.