“Computational Civil Engineering - "Intersections" International Journal

“Computational Civil Engineering 2005”, International Symposium 219As a consequence, it is not probable that bridges are in a free process ofdegradation. The longer the period of time, the higher chances are that moreinterventions were performed with out records. For the truncated period,extrapolation can be performed assuming and accepting a certain degree ofuncertainty.After truncation and regression analysis one can note that the evolution respects therules of the theory of reliability: an initial zone of rapid degradation, followed byan interval of relative evenness, and finally a zone of fast degradation due toobsolescence.Figure 2. Analysis of I ST values on truncated interval3. ANALYSIS OF A PARTICULAR CONDITION INDEX (C 1 )Even the analysis of an index likeI STrequires strong statistical knowledge and aspecial attention, it is however relatively simple to perform the computation for thispart as the characteristics are visible or intuitive. It is Much more difficult toanalyze the indicators with a reduce domain, i.e. analysis for the evolution of C1(main resistance elements of the superstructure) which is presented in Fig.3. Thevalue cloud is extremely scattered and the regression consistence does not presentconsistence (is ascendant for some range).Due to the fact that no result may be deduced from raw data the evolution will bestudied based of annual average, Fig.4. The time interval is partitioned in 3 zonesand regression will be performed on each one. For the first zone the trend line isforced to pass through the value 10 for t=0.