Structural assessment and upgrading of sewers based on inspection results

A decision-support-system has been developed for the rehabilitation planning of sewers based on inspection results. The heart of the system is the structural reliability module that receives input on damage from inspections and performs structural analyses to assess the current structural condition of the sewer. Similar analyses are performed at future times but with different parameters based on the evolution of (1) loads; (2) corrosion; and (3) soil-structure interaction. Some of the parameters are treated as random variables and the outcome is the probability of structural failure as a function of time which is needed in the rehabilitation module that selects the most appropriate rehabilitation method. Then the system prioritizes rehabilitation projects based on the structural condition of the sewer and the impact that sewer failure might have. Results show that high leakage promotes structural failure and that the influence of nonseismic effects in the presence of clay soil is larger than in sand. On the other hand, the influence of seismic effects is more pronounced in sand than in clay.