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article · Scientific Reports

Shear behavior of high-strength reinforced concrete beams with circular openings under fire exposure

Abstract

This study investigates the shear behavior of high-strength concrete (HSC) beams with large circular web openings subjected to elevated temperatures. Internal (steel fibers at 0.5% and 1.0% by volume) and external (ferrocement jackets) retrofitting techniques were evaluated. Nine beams were experimentally tested, including solid control specimens, un-strengthened beams, and retrofitted beams. Exposure to 500 °C resulted in a shear capacity reduction of up to 68% for beams with 150 mm openings. After thermal exposure, steel fibers enhanced the residual shear strength by up to 16.4%, while ferrocement jackets achieved recovery levels of up to 14.5%. A parametric finite element study was conducted considering opening diameters ranging from 100 to 200 mm and temperature levels between 400 and 600 °C, demonstrating strong agreement with experimental results (average deviation ≤ 3%). The findings provide validated insights into the combined effects of geometric discontinuities and thermal degradation and support the development of effective retrofitting strategies for HSC beams under fire conditions.

Research topics

  • Fire effects on concrete materials
  • Structural Behavior of Reinforced Concrete
  • Structural Load-Bearing Analysis

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DOI: 10.1038/s41598-026-43162-y

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