Impact of Long-term Material Degradation on Seismic Performance of a Reinforced Concrete Bridge

A Performance-Based Earthquake Engineering (PBEE) assessment methodology is being used to study the impact of long-term material degradation on seismic performance of reinforced concrete bridges. The methodology, currently under development by the Pacific Earthquake Engineering Research Center, is being applied to an overpass with typical California highway details, and preliminary results are presented. The structure was analyzed in its sound as well as a deteriorated condition considering spalling and reduced reinforcing steel areas resulting from corrosion. A simple modeling approach was employed to study analytically the impact of such deterioration on drift demands and potential damage to the structure. The ground motion occurrence, resulting structural response, and predicted damage were combined in PBEE assessments of the sound and deteriorated bridges. The deterioration resulted in a factor-of-three increase in the frequency of steel yielding caused by earthquake shaking. The PBEE framework provides a systematic method to compare quantitatively the effect of deterioration on seismic damage.