The introduction of Key Performance Indicators (KPI) for predicting the state of health

Paper in proceeding, 2012

As durability of concrete infrastructure is a major concern worldwide, numerous approaches have been developed. It is a common practice nowadays to ensure durability of reinforced concrete structures by specifying a concrete mix and a nominal cover at the design stage to cater for the exposure environment. This in theory should produce the performance required to achieve a specified service life. Although the European Standard EN 206-1 specifies variations in the exposure environment, it does not take into account the macro and micro climates surrounding structures, which have a significant influence on their performance and service life. Therefore, in order to construct structures which will perform satisfactorily in different exposure environments, the following two aspects need to be developed: a performance based specification to supplement EN 206-1 which will outline the expected performance of the structure in a given environment; and a simple yet transferrable procedure for assessing the performance of structures in service. This will allow the asset managers not only to design structures for the intended service life, but also to take informed maintenance decisions should the performance in service fall short of what was specified. The approach adopted in the paper is to select a reliable service life model and outline all the quantifiable (measurable) variables that contribute to the performance of structures in chloride environments. These variables are termed as Performance Indicators (PI). A case study of three concrete piers exposed to the North Sea is used to evaluate the relative influence of the PI on service life. A sensitivity analysis is carried out to determine the most significant of the PI termed as key performance indicators (KPI) which will have the greatest impact on the performance and service life of the structure. It is expected that KPI’s would allow asset owners to easily assess the state-of-health of their structures and devise appropriate maintenance strategies.