An overview of corrosion and experimental studies on corroded mild steel compression members

Abstract

The performance of steel structures are strongly influenced by the damage due to corrosion, whose control is a key aspect for design and maintenance of both new and existing important structures. This paper presents various issues related to corrosion, types of corrosion, chemical reactions and electrochemistry behind corrosion of steel structural elements, approaches to quantify corrosion and experimental studies on corroded coupons and compression members made of angle and tubular sections. The various corrosion models for structural applications are also presented, by considering the depth of corrosion along with various influencing parameters. Based on experimental studies on coupons, it is concluded that corrosion results in reduction in metal thickness followed by weight loss and reduction in mechanical strength. Galvanostatic method is adopted to corrode structural steel specimens by keeping current as constant. The thickness loss and weight loss are the main parameters measured to quantify the amount of corrosion. From the studies, it is concluded that for the corroded specimens, along with reduction in thickness, the geometric properties such as area, moment of inertia, radius of gyration, section modulus changes. As the corroded surface is highly irregular these changes may not be linear. Variation in slenderness ratio also noticed for corroded specimens. In effect the overall capacity of the section reduces due to corrosion. Identifying the intensity level of corrosion such as mild, moderate and severe along with the form and location of corrosion are the other parameters discussed. A drastic reduction in mechanical properties i.e., yield and ultimate strength are observed for severely corroded specimens.