TIME VARIANT RELIABILITY ANALYSIS OF REINFORCED CONCRETE BRIDGES SUBJECTED TO BOTH LOADING AND CHLORIDE INDUCED DEGRADATION

Abstract

The reliability of the structural performance of reinforced concrete bridges is affected by aging, aggressive environments and traffic loadings. Time-variant reliability analysis of a two span reinforced concrete bridge was investigated using First Order Reliability Method (FORM). Limit state functions considering ten failure modes for members in bending were considered to accommodate the time-dependent effects in the structural reliability analysis. The entire process was implemented via a developed program using MATLAB. The program is automated to calculate the reliability indices using the limit functions for each of the ten failure modes over the bridge service life of 120years at 10years intervals. The random variables are imputed directly through the interactive part of the program while other functions are imbedded in the main program input directory. The results show that the load capacity loss ranges between 9.41% for the least deteriorated member failure mode to 100% for the most deteriorated member failure mode as the corrosion rate increases from 0.02 to 0.06 mm/year at load growth rate of 0.005. Lower capacity losses were however obtainedat a constant load (no load growth), with losses ranging from 0.25% for the least degraded member failure mode to 34.47% for the most deteriorated....