Shear behavior of ultra-high-performance concrete beams reinforced with high-strength steel bars

This study was conducted to investigate the effects of key structural parameters on the shear behavior of non-prestressed ultra-high-performance concrete (UHPC) beams passively reinforced with high-strength steel bars. The parameters studied were shear span to effective depth ratio a/d; volume fraction of steel fibers V_f; longitudinal reinforcement ratio ρ; and stirrups spacing s. Ten beam specimens with cross-section dimension (width x depth) 5.91 x 8.86 in. (150 x 225 mm) were quasi-statically loaded to failure on a simple span length of 68.9 in. (1.75 m), under a four-point loading configuration. The statistical analysis of the experimental data indicated that a/d, V_f, and s have significant effects on the shear capacity of UHPC beams, while the effects of ρ are quite insignificant. A mechanistic model for estimating the shear capacity of reinforced UHPC beams was developed, validated, and shown to be reasonably accurate.