In recent years, increasing consideration has been given to the life extension of deteriorating structures. This is based on the fact that a growing percentage of civil infrastructure as well as buildings are threatened by obsolescence and that due to simple monetary reasons, this can no longer be countered by simply rebuilding everything anew. Hence, maintenance interventions are required, which allow partial or complete structural rehabilitation. However, the same economic reasoning, which leads to the implementation of maintenance policies, has also to be applied to maintenance strategies themselves. In other words, maintenance interventions have to be economically reasonable, that is, maintenance expenditures have to be outweighed by expected future gains. If this is not the case, then indeed the structure is obsolete—at least in its current functional, economic, technical, or social configuration—and innovative alternatives have to be evaluated.
      Thus, the overall objective of maintenance interventions is to find an optimal balance between recovering the profitability of structural operation over a designated time horizon and the maintenance expenditures spent—without compromising safety issues. Such a balancing is commonly done by life-cycle cost-minimization considering all significant costs (such as, for example, costs of construction, operation, maintenance, or failure) throughout the lifetime. The implicit assumptions hereby are that all maintenance alternatives have the same benefit, benefit does not depend on the deterioration state of the structure and benefit always outweighs all costs. A reason for not specifying benefit explicitly is the traditional focus of structural engineers on preventing structural collapse, though this is gradually changing through a renewed interest in performance-based design criteria and reliability verification. However, specifying benefit rates explicitly not only allows a more refined optimization of maintenance interventions, but also allows the determination of optimal lifetimes and acceptable failure rates.

 

 

Refereed Journals:

Higuchi, S., Macke, M.: “Cost-benefit analysis for the optimal rehabilitation of deteriorating structures.” Structural Safety, in press [doi | ].

Higuchi, S., Macke, M.: “Cost-benefit based optimization of maintenance interventions for deteriorating structures.” Doboku Gakkai Ronbunshuu A, JSCE, Vol. 63, No. 4, pp. 727-743, 2007 [doi | (464k)].

Higuchi, S., Macke, M.: “Cost-benefit based optimization of maintenance interventions for deteriorating structures.” Structural Engineering/Earthquake Engineering, JSCE, Vol. 24, No. 2, pp. 131s-147s, 2007 [doi | (502k)].

Macke, M., Higuchi, S.: “Optimizing maintenance interventions for deteriorating structures using cost-benefit criteria.” Journal of Structural Engineering, ASCE, Vol. 133, No. 7, pp. 925-934, 2007 [doi | (153k)].

Conference Proceedings:

Higuchi, S., Macke, M.: “Cost-benefit analysis of maintenance interventions for deteriorating structures.” In: Kanda, J., Takada, T., Furuta, H. (eds.), Proc. 10th Int. Conf. on Applications of Statistics and Probability in Civil Engineering, Tokyo, Japan, July 31-August 3, 2007. Taylor and Francis, London, 2007 [ (300k)].

Higuchi, S., Macke, M.: “Cost-benefit criteria in optimizing maintenance strategies.” In: Proc. IABSE Symposium Weimar 2007—Improving Infrastructure Worldwide, Weimar, Germany, September 19-21, 2007. IABSE, Zürich, 2007 [ (221k)].