Reliability-Based Optimal Planning of Maintenance and Inspection

Authors

John D.Sørensen and Michael H. Faber

Abstract

Major deterioration mechanisms for infra-structural systems such as bridges, tun-nels and dams are chloride initiated corrosion of reinforced concrete and fatigue damage in steel structures. Corrosion of the reinforcement is a significant problem for a large number of reinforced concrete structures since it can result in very ex-pensive maintenance and repair actions. Further a substantial decrease of the load-bearing capacity may occur leading to an unacceptable level of safety for the struc-ture. One mode of corrosion initiation is that the chloride content around the rein-forcement exceeds a critical threshold value. In the present paper a statistical model is described by which the chloride content in a reinforced concrete structure can be predicted. The model is used in reliability-based inspection and maintenance plan-ning for concrete structures. For steel structures a simplified and generic approach for risk-based inspection planning of fatigue sensitive structural details is de-scribed. Fatigue sensitive details are categorized according to their Fatigue Design Factor (FDF) and SN curve. Using a fracture mechanics model calibrated on a probabilistic basis to the appropriate SN-curve, cost-optimal inspection and repair planning can be performed. The procedure is illustrated by an example considering inspection planning of welded longitudinal stiffeners in steel bridges.

Published in/by

Life-Cycle Cost Analysis and design of Civil Infrastructure Systems, Proceeding to 1st US-Japan Workshop, Hawai, August 7-8, 2000