Rehabilitation of underground garages – defining a cost function for use in the decision-making process

Performance-based design concepts are a key tool to ensure the durability of reinforced concrete structures. Their application relies on the definition of limit states, for which defined limit state functions represent the probability of exceeding a particular condition. Such limit state functions are available for depassivation (initiation of reinforcement corrosion) in case of concrete carbonation and/or chloride-induced corrosion. Moreover, not only the knowledge about the exceedance of a certain limit state is of interest, but also the related consequences such as the costs for the subsequent repairs. This contribution analyses the inspection reports and the tendering documents of well-documented rehabilitations of parking garages. The focus was set on chloride-induced corrosion since it is the main cause of the rehabilitations. The analysis focused on the following aspects: the estimation of the reliability index value that led to the rehabilitation, the rehabilitation method used, and finally an indicative estimation of the incurred costs. The results unveil that for both conventional and cathodic protection rehabilitations, the reliability index had similar ranges for columns. Furthermore, in one meticulous project, a clear relationship between the estimated reliability index and the incurred costs was observed. However, this finding was less evident in other projects, for which a step cost function was more suitable.