Effect of reinforcement corrosion on punching shear of RC flat slabs incorporating steel and synthetic fibers

ABSTRACT Reinforcement corrosion weakens the punching shear capacity of RC flat slabs. This study tested twelve large-scale slabs (1500 × 1500 × 100 mm) with hooked-end steel or macro-synthetic fibers (0.5–1.0% by volume) and control samples. Half the specimens underwent impressed current corrosion regime (500 µA/cm² for 36 days with 3.5% NaCl wet–dry cycling) before monotonic central punching tests. Corrosion reduced capacity and ductility. Control slabs lost approximately 16% of their peak load capacity due to corrosion. Fibers increased punching strength in uncorroded slabs and mitigated corrosion losses; a 0.75% synthetic-fiber slab lost only 10.7%. Fibers also delayed corrosion-induced cracking, limited crack widths and cover spalling, and delivered higher post-peak residual capacity and energy absorption. Steel fibers yielded larger gains in peak load, while synthetic fibers were particularly effective in controlling cracks and containing damage. Overall, discrete fibers substantially enhanced the punching shear resilience of flat slabs in corrosive environments.