Proposed shear capacity equation for ultra-high performance fiber reinforced concrete beam containing coarse aggregate

Authors：Smith, Abutu Simon John; Xu, Gang^*

Source：Structures, 2023, 56: 105030.

DOI：10.1016/j.istruc.2023.105030

• Beam
• Coarse aggregate
• Shear capacity equation
• Ultimate load
• Ultra-high performance fiber reinforced concrete

This paper proposes a shear capacity equation for ultra-high performance fiber reinforced concrete beam containing coarse aggregate (UHPFRC-CA) and without coarse aggregate (UHPFRC) that captures all UHPFRC ' s direct and indirect shear influencing factors. Six beam samples (each sample containing two beam specimens) were tested for shear strength under four point loading configuration using shear span-depth ratio (a/d), percentage volume of steel fiber (V-f), shape of steel fiber and stirrup spacing (s) as shear design parameters to obtain their ultimate shear strength (V-u). The obtained V-u was subjected to Analysis of Variance (ANOVA) to assess the significance of adding a coarse aggregate factor (d(ca)) to the proposed equation. The proposed equation was validated by comparing its Vu with this study ' s experimental Vu, other researchers ' V-u and V-u estimated using existing shear equations. ANOVA results showed that d(ca) is significant in the V-u of UHPFRC-CA beams. Findings also revealed that the proposed equation does not only predict the Vu of UHPFRC-CA beams with a very high degree of accuracy but also gives better estimates of the V-u of UHPFRC-CA and UHPFRC beams when compared with the existing shear equations considered in this study. Further findings showed that the proposed equation reflects the effect of changes in V-f, a/d,s,rho shape of steel fiber and maximum size of coarse aggregate better than the existing shear equations for UHPFRC beams. Therefore, the proposed equation can be safely use for the shear design of UHPFRC-CA beam whose compressive strength ranges from 150 N/mm(2) to 170 N/mm(2).rho