Volume 23, Issue 60, July - December, 2026

Numerical and Experimental Study of UHPC Beams with Square and Rectangular Openings Reinforced with Steel Plates

Hayder SH Hudaib^1♦, Hayder MJ Al-Khafaji²

¹Civil Engineering Department, College of Engineering, University of Babylon, Babylon, 51001, Iraq.
²Civil Engineering Department, College of Engineering, University of Babylon, Babylon, 51001, Iraq.

^♦Corresponding author
Hayder SH Hudaib, Engineering Department, College of Engineering, University of Babylon, Babylon, 51001, Iraq

ABSTRACT

In the present work an integrated experimental and computational method is used to explore the structural performance of ultra-high-performance concrete (UHPC) beams with square and rectangular transverse web apertures reinforced with externally bonded steel plates. Five UHPC beam specimens were examined under four-point bending, consisting of a control beam, beam with a square opening, a beam with a rectangle opening, and their corresponding reinforced specimens. A three-dimensional nonlinear finite element model was created in Abaqus to mimic the nonlinear behavior, crack growth and interaction between the UHPC and the external strengthening system. The experimental results showed that the internal force transfer mechanism was severely disturbed by the openings, and the stress concentration around the opening boundaries was localized, which caused the ultimate load capacities of the beams with square and rectangular openings to decrease by approximately 11.0% and 11.7%, respectively, compared with those of the control beam. The rectangular hole with elongated shape and larger interruption of the stress flow led to more severe stiffness degradation and fracture localization. The externally bonded steel plates increased the load-carrying capacity, slowed the fracture propagation, and improved the stress redistribution, significantly enhancing the structural response. The reinforced square-opening beam had a little higher capacity than the control specimen, while the strengthened rectangular-opening beam showed partial structural recovery. The computational predictions were in excellent accord with the experimental data in terms of load-deflection response, fracture patterns and ultimate load capacity. The results confirmed that the steel plate strengthening is an efficient rehabilitation approach for UHPC beams with web apertures nevertheless the strengthening efficiency largely depends on the opening shape.

Keywords: ultra-high-performance concrete (UHPC), Square and Rectangular Openings, Steel Plates Reinforcement

Indian Journal of Engineering, 2026, 23(59), e9ije1721

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Published: 21 August 2026