Performance evaluation of deteriorated reinforced concrete flat slab-column connections: An experimental study

The research presented in this paper examines the impact of corrosion on flexural reinforcement and its subsequent effect on the structural performance of reinforced concrete (RC) flat slabs. A total of seven experimental-scale RC flat slabs were constructed and tested. The slabs measured 1500 mm × 1500 mm × 150 mm. Flexural reinforcement was intentionally corroded in a vulnerable area to two-way shear, specifically within an 800 mm × 800 mm region. A uniform corrosion level was achieved using an accelerated corrosion technique. This involved applying a maximum constant current density of 200 μA/cm 2 through the flexural reinforcement for three months. The findings were analyzed in terms of load-deflection curves, failure modes, crack patterns, stiffness, energy absorption, toughness, and ductility index. A higher flexural reinforcement ratio caused a decline in post-cracking stiffness in all specimens (especially with corrosion). It also increased two-way shear capacity but reduced correlated deflection capacity. Corrosion reduced two-way shear and deflection capacity, especially at lower flexural reinforcement ratios. A higher flexural reinforcement ratio in all specimens reduced ductility (to a lesser extent in the presence of corrosion) but increased toughness and resilience (especially in the presence of corrosion). Moreover, corrosion altered cracking patterns, shifting them from radial to tangential, and changed failure modes from flexure to flexural-shear, or from flexural-shear to brittle two-way shear. The experimental failure modes of the specimens were compared against the predictions of four different design codes. None of these codes provided reliable predictions for the corroded specimens. Consequently, two correction coefficients have been proposed to account for the effects of corrosion on flexural reinforcements. These coefficients have the potential to significantly improve the safety and reliability of future RC structure designs by more accurately accounting for the detrimental effects of corrosion. • An extensive investigation was conducted to evaluate the two-way shear capacity of reinforced concrete flat slab connections. • A direct current (DC) power supply with multiple outputs was employed to systematically induce uniform corrosion across the test specimens, ensuring comparative and reliable experimental results. • A corrective coefficient was developed to significantly improve the reliability of future design practices in RC slab structures.