Effect of variability of material properties on resistance of existing post-tensioned concrete bridge – case study

The study deals with the sensitivity analysis in determining the load-bearing capacity of existing bridges made of post-tensioned precast girders. Focusing on a specific road bridge, the effect of variations of important basic variables on load-bearing capacity is investigated. When assessing existing structures, values of some basic variables often need to be estimated due to the lack of background information (missing documentation, limited range of structural survey). The aim of this study is to identify basic variables with key influence on load-bearing capacity of the bridge. Numerical example is specifically focused on the mid-span cross-section of a simply supported KA-73 beam structure. It appears that corrosion is the key factor affecting reliability of the bridge at the Ultimate Limit State while prestressing loss is dominating the Servieability Limit State verification. Further research will be focused on reliability analysis of bridges based on the results of structural surveys.