Title: Effects of Corrosion Damage on the Load Capacity of a Reinforced Concrete Peir Structure

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Publication: CIA

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Date: 2/13/2011

Abstract:
A reinforced concrete pier structure, built in 1971, has evidently developed severe chloride-induced corrosion damage due to exposure to marine environment. Inspection conducted in 2006 revealed severe vertical cracking in the piles and extensive horizontal cracking and delamination of the cover concrete at the crosshead soffits. Previous ARRB data had shown that the 22mm and 32mm reinforcement bars had lost 1.5 mm by 2000 due to chloride-induced corrosion. Based on the then prevailing corrosion rate, an additional 0.4 mm was estimated to have been lost between 2000 and 2006. Several stirrups in the crossheads, under the wheel path, were found to be severely corroded or broken. The deck slabs and beams were far less affected by chloride-induced corrosion. The design load capacity of the pier was originally for 7 Tonne (single axle) and 10 Tonne (double axle) vehicles. Calculations based on the observed deteriorations showed that the load ratings of the piles, beams and deck slabs remain unchanged (despite the deterioration), but the crossheads were found to be severely deficient in shear capacity due to loss of stirrups. Based on the AS 5100 requirements , the load rating needed to be reduced to 3.6 tonnes and 5.2 tonnes for single and double axle vehicles, respectively. Costs for the remediation options, including cathodic protection, are estimated to be in the range of $4-5M.