Predicting service life of chimneys and cooling towers based on monitoring

Abstract

Actual conditions and prediction of residual service life of existing reinforced concrete chimneys and cooling towers should be assessed considering technical data obtained from monitoring and the principles of Eurocodes, ISO standards and fib Model Code 2010. In the contribution the criteria for assessing carbonation progress are discussed in detail, utilising experience and long-term measurements of the major power producer in Central Europe. Available normative documents indicate that for existing structures, the target reliability index for durability limit states should be around 1.3. When reliability decreases below this level, the structure should be repaired. A limiting value of reliability index is determined assuming that the structure is to be repaired during next three years. Once the limit is exceeded, asset management is informed and starts planning structural intervention. It is further shown how remaining service life can be assessed using statistical treatment of a time series of reliability indices and their comparison with a target level.