Lifetime Bridge Maintenance Strategies Based on System Reliability

This study proposes a methodology for a system reliability-based condition evaluation of existing highway bridges. The approach is illustrated for an existing steel bridge located in Colorado. USA. An optimum lifetime repair strategy based on minimum expected cost is developed. The initial optimum repair strategy is updated using both biennial visual inspections and specific non-destructive evaluation testing

Probabilistic maintenance and optimization strategies for deteriorating civil infrastructures

In developed countries, civil infrastructures are one of the most significant investments of governments, corporations, and individuals. Among these, transportation infrastructures, including highways, bridges, airports, and ports, are of huge importance, both economical and social. Most developed countries have built a fairly complete network of highways to fit their needs. As a result, the required investment in building new highways has diminished during the last decade, and should be further reduced in the following years. On the other hand, significant structural deteriorations have been detected in transportation networks, and a huge investment is necessary to keep these infrastructures safe and serviceable. Due to the significant importance of bridges in the serviceability of highway networks, maintenance of these structures plays a major role. In this paper, recent progress in probabilistic maintenance and optimization strategies for deteriorating civil infrastructures with emphasis on bridges is summarized. A novel model including interaction between structural safety analysis,through the safety index, and visual inspections and non destructive tests, through the condition index, is presented. Single objective optimization techniques leading to maintenance strategies associated with minimum expected cumulative cost and acceptable levels of condition and safety are presented. Furthermore, multi-objective optimization is used to simultaneously consider several performance indicators such as safety, condition, and cumulative cost. Realistic examples of the application of some of these techniques and strategies are also presented.The authors gratefully acknowledge the partial financial support of the U.K. Highways Agency and of the U.S. National Science Foundation through grants CMS-9912525 and CMS-0217290. The second author also acknowledges the support of the Portuguese Science Foundation (FCT)

Optimum maintenance strategy for deteriorating bridge structures based on lifetime functions

The highway networks of most European and North American countries are completed or close to completion. However, many of their bridges are aging, and in the United States alone a very significant part of the about 600,000 existing bridges is considered to be deficient and must be replaced, repaired or upgraded in the short term. The funds available for the maintenance of existing highway bridges are extremely limited when compared with the huge investment necessary, and must, therefore, be spent wisely. In this paper, a model based on lifetime functions for predicting the evolution in time of the reliability of deteriorating bridges under maintenance is presented. This model uses the probability of satisfactory system performance during a specified time interval as a measure of reliability and treats each bridge structure as a system composed of several components. In this manner, it is possible to predict the structural performance of deteriorating structures in a probabilistic framework. In addition, the optimum maintenance strategy is identified using as objective the minimization of the present value of the life-cycle maintenance cost. An existing bridge is analyzed using lifetime functions and its optimum maintenance strategy is found.U.S. National Science Foundation - CMS-9912525; CMS-0217290.Colorado Department of TransportationDutch Ministry of Transportation, Public Works, and Water Management

Multi-objective probabilistic optimization of bridge lifetime maintenance : novel approach

Due to the increase in deterioration of the existing civil infrastructure, in particular bridge networks, governments and highway agencies are trying to find methods that allow a consistent and rational management of existing bridges. In this paper, a novel approach is presented. This approach uses multi-objective probabilistic optimization over time and defines performance of existing bridges in terms of lifetime condition, safety, and cost. The proposed approach aims at providing a tool for optimal maintenance management policy definition of a large group of similar structures. Consequently, emphasis is put on the use of limited information and low computational cost. Applications to real cases are presented showing the applicability of the method as well as its advantages in terms of reduction of costs and improvements in performance.(undefined

Lifetime multi-objective optimization of maintenance of existing steel structures

In this paper, the lifetime performance of deteriorating structures, defined by their time dependent condition index and reliability index, is analyzed. The effect of preventive and essential maintenance actions on performance and cost in predicted, and the optimal times of application of preventive and essential maintenance actions are found. Due to significant uncertainty in the initial performance, effects of deterioration and of maintenance actions, as well as, times of application and cost of maintenance actions, the analysis is performed in a probabilistic framework. The reduction in performance due to deterioration is simulated using an extension of the model proposed by Frangopol (1998). The probabilistic condition index, reliability index, and cumulative cost profiles are computed using Latin Hypercube simulation. Optimization of times of application is performed using genetic algorithms. Results show the significant importance of preventive maintenance actions in reducing the lifetime cost of existing structures, but also their fundamental role of essential maintenance action in keeping structures safe and serviceable during the entire lifetime