Seismic Performance of Corroded RC Frames Using The Pushover Method

Abstract

Corrosion is a natural process that transforms the raw material into chemically stable for oxides, hydroxides and sulphides. It gradually reduces the capacity of the materials by chemical and electrochemical reactions to their environment. For example: - It won't rust whether we put nail in dry air or Completely falls into water. But it's going to deteriorate when it's immersed in water and later in the air. In the case of steel surrounded mass concrete, concrete is a porous substance containing water molecules in voids during the healing cycle or during rainy season or other environment with relatively high humidity that may cause corrosion to the concrete containing water. However, it is not necessary to corrode steel bars surrounded by mass concrete because concrete is alkaline and alkaline is acidity's opposite nature. Alkalinity due to high calcium, magnesium and sodium oxides within the concrete micro voids can protect steel from corrosion. The alkalinity creates a passive coating of oxides and hydroxides off iron and partially cement on the steel reinforcement sheet. Passive layer is dense and it prevents the occurrence of corrosion. Passive layer does’t remains more duration, it breaks due to carbonation and permeability of chlorides to the steel reinforcement. After passive layer broken off rust will appear on the surface of steel bar, due to chemical reaction of carbonation and penetration of chlorides (Both chemical reactions are same). If the water trapped in the concrete void melts so reinforced steel corrosion occurs in concrete.