Condition Evaluation for Reliability Assessment of Existing Structures

Risk analysis is a necessary component of project planning and maintenance. Among other facets, risk analysis includes evaluation of loads (demands) and responses (capacities), or the reliability of a structure. Reliability assessment is based on a logical format for analyzing the probability of unsatisfactory performance using probabilistic estimates of loadings and responses. This paper discusses specific aspects of structural reliability assessment related to the current condition of constructed structures. The most accurate application of reliability relies on historical performance data for identical structures under like conditions. Rarely is such data readily available, however. Differences in environment, construction quality, design, loadings, maintenance, etc. can have substantial impact on the performance of a structure. This impact can be initially estimated, but divergences from initial estimates during the life of the structure are more difficult to determine and quantify. Condition assessment information can be used as an informative tool and more formally to create a performance-correlated database. This database can be used for adjusting the reliability assessments as a structure's condition deviates from the predictions made for a structure of the current age and loading history.