Author Identifier
Hossein Mirzaaghabeik: https://orcid.org/0000-0002-7068-6015
Sanjay Kumar Shukla: https://orcid.org/0000-0002-4685-5560
Nuha S. Mashaan: https://orcid.org/0000-0002-0331-4254
Document Type
Journal Article
Publication Title
Structures
Volume
76
Publisher
Elsevier
School
School of Engineering
Funders
Edith Cowan University
Abstract
This study examines the shear behaviour of ultra-high-performance concrete deep beams (UHPC-DBs) reinforced with three fibre types: 2 % hooked-end (HE) steel fibres, 0.76 % 5D steel fibres, and 0.11 % Forta-Ferro (FF) synthetic fibres. It evaluates the effects of fibre type, fibre content, vertical web reinforcement (ρsv), and shear span-to-depth ratio (λ) on shear capacity. Load-deflection curves, crack patterns, and ρsv strain were analysed, and the optimal ρsv was determined using the particle swarm optimization (PSO) algorithm to maximise shear capacity while minimising costs. Findings reveal that, compared to specimens without ρsv, those with ρsv = 0.38 % exhibit shear capacity increases of 12.42 %, 15 %, and 16.46 % for specimens reinforced with HE, 5D steel fibres, and FF synthetic fibres, respectively. Additionally, ρsv strains increase by 19.99 %, 26.45 %, and 24.03 % for specimens reinforced with HE, 5D steel fibres, and FF synthetic fibres, respectively, when ρsv rises from 0.075 % to 0.38 %. Higher ρsv enhances stiffness and ductility, underscoring its role in improving these properties. Additionally, specimens reinforced with 2 % HE fibres exhibit more ductile behaviour than those reinforced with 0.76 % 5D steel fibres. Beams reinforced with 0.11 % FF achieve 80.35 % of the shear capacity of those reinforced with 0.76 % 5D, indicating FF as a viable alternative. Shear-compression failure occurs in all UHPC-DBs at λ = 0.923 and λ = 0.739, except for those reinforced with 2 % HE steel fibres and ρsv values of 0.19 %, 0.30 %, or 0.38 %, which fail in diagonal tension. An increase in ρsv reduces crack width in UHPC-DBs reinforced with all three fibre types. Additionally, UHPC-DBs reinforced with 5D fibres exhibit narrower cracks than those reinforced with FF fibres. Three 3D graphs were developed to illustrate the combined effect of λ and ρsv on the shear capacity of UHPC-DBs. The results show that increasing ρsv and decreasing λ enhance shear capacity. These findings highlight a gap in ACI 318–19, which does not explicitly address the interaction between λ and ρsv in fibre-reinforced UHPC-DBs, suggesting that these graphs could help refine existing standards. When the optimal ρsv of 0.19 % is incorporated, the resulting shear capacity reaches 90.47 %, 98.42 %, and 89.23 % of the capacities achieved with ρsv = 0.38 % for UHPC-DBs reinforced with HE, 5D steel fibres, and FF synthetic fibres, respectively, while reducing steel reinforcement costs by 46 %.
DOI
10.1016/j.istruc.2025.109038
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Mirzaaghabeik, H., Shukla, S. K., & Mashaan, N. S. (2025). Effects of vertical reinforcement on the shear performance of UHPC deep beams with synthetic and steel fibres. Structures , 76, 109038. https://doi.org/10.1016/j.istruc.2025.109038