Span length-dependent load-carrying capacity of normal concrete - HPFRC beams

The dependence of load-carrying capacity on span length of beams, which contained a combination of normal strength concrete (NC) - High-performance fiber-reinforced concrete (HPFRC), was investigated in this study. The used HPFRC contained 1.0 vol.% long hooked blended with 0.5% short smooth fibers. Two types of span length were designed as 300 mm and 450 mm while dimensions of beam sections were identical with depth × width of 150 × 150 mm2. Each span included five types of partial structural materials as follows: Short 1 and Long 1 had no reinforcement with full of section using HPFRC, Short 2 and Long 2 had reinforcements with a full of section using HPFRC, Short 3 and Long 3 had reinforcements with a half of section using HPFRC at beam bottom, Short 4 and Long 4 had reinforcements with a third of section using HPFRC at beam bottom, Short 5 and Long 5 had reinforcements with a half of section using HPFRC at beam top. All beams were tested under three-point bending test. The shorter beam generally exhibited the greater load-carrying capacity than the long beam using same section type. The shear failure mode was dominant in case of the span/depth ratio less than 3. The HPFRC located at bottom of beam created the more effectiveness for enhancement of load-carrying capacity and stiffness of the beam, in comparison with the HPFRC placed at top of beam. The most effective zone of beam for HPFRC strengthening was at extreme tension fiber. Keywords: high-performance; composite beam; shear failure; bending resistance; load-carrying capacity.