RELIABILITY-BASED PREDICTION OF SERVICE LIFE FOR REINFORCED CONCRETE STRUCTURES SUBJECTED TO CORROSION OF STEEL BARS

摘要

A practical method is proposed to predict the residual service life for reinforced concrete structures affected by steel corrosion. Durability of a structure is defined as time-dependent safety and serviceability. The service life of a reinforced concrete structure can be determined by corrosion initiation stage (T1), corrosion progress stage 1 (T2) before cover cracking and corrosion progress stage 2 (T3) until reaching the limit status of the durability. T1 and T2 can be achieved by the given models of concrete carbonation or chloride penetration and steel corrosion rate before cover cracking,respectively. T3 is obtained by the model of steel corrosion rate after cover cracking, the calculation of structural performance of concrete beams with corroded steel bars and the limit state of durability. A reinforced concrete member or structure reaches its limit of the durability when the grade of safety or serviceability transfers from b to c due to steel corrosion, considering that a structure with safety or serviceability of grade c needs repairing in the current standard and code for inspection and assessment of existing building structures. By step-by-step trial method, the safety grade characterized with the ratio of resistance and load effect, and the serviceability grade characterized with the deformation, longitudinal crack width and transverse crack width at different continuing service period can be achieved by the corresponding model. It is verified that the proposed method to predict the service life for reinforced concrete structures subjected to steel corrosion is feasible by the analysis of an example.