Flexo-Compressive Strength of Reinforced Concrete Frame Elements Considering Corrosion Process

Abstract

Frame buildings are prone to cracking because of their deformation by normal and extreme events such as temperature and earthquakes. Even though the crack widths are limited in the structural design, a cracked cover reduces the corrosion protection of reinforcing steel. Therefore, the load capacity of structures can be compromised prematurely. This paper aims to evaluate the flexo-compressive strength of deteriorated reinforced concrete (RC) elements in the corrosion process. To that end, a methodology to calculate the residual strength capacity was proposed, considering the influences of crack widths and cover width on the corrosion level—structure age relation of RC elements. The strength deteriorations caused by the concrete cracking and the steel corrosion were incorporated according to structure age. The residual strength was studied using parametric analyses, whose variables were the crack width, the cover width, the rebar diameter, and the structure age. The results showed that the cracked frame elements reduced their serviceability life by up to 62%, although their crack widths were within range recommended by the design codes (lesser than 0.30 mm). In 25 years, the corrosion effects reduce the element strength by up to 44%. This is due to the corrosion protection provided by the cracked cover becomes insignificant, reducing the initiation time. Thus, considering the corrosion deterioration can prevent strength overestimations up to 1.46 times. Additionally, according to their current state, the proposed methodology provides a practical estimation of flexo-compressive strength in corroded RC elements.