The Effect of Changing Decision Makers on the Optimal Service Life Design of Concrete Structures

Authors

Kazuyoshi Nishijima, Daniel Straub and Michael H. Faber

Abstract

Service life costing for durability based design of concrete structures is considered in the context of real life organizational boundary conditions with changing decision makers and short time budgeting. A decision theoretical formulation for the optimal design of structures is given, facilitating that a balance between protective design measures and future inspection and maintenance activities is achieved. Furthermore, taking basis in a framework developed for sustainable decision making it is shown how the design optimization problem can be formulated such that the preferences of several subsequent decision makers responsible for a structure over its lifetime can be considered with equal weight; i.e. a multi-decision-maker perspective. The developed framework may also be utilized for budgeting of future inspections, repairs and failures. As an example of the application of the decision framework, the problem of optimal lifecycle cost based design of the concrete cover thickness for concrete structures is analyzed. The considered structures are subject to chloride induced corrosion and optimal designs are derived for different environmental exposure conditions, for concretes of different w/c-ratios and as a function of the duration over which the individual decision makers are acting. Finally the significance of the proposed framework is highlighted by comparison of expected service life costs and required budgets of optimal design decisions derived on the basis of the classical onedecision-maker perspective and on the basis of the multi-decision-maker perspective derived herein.

Published in/by

Proceedings LCC04, 4th International Workshop on Life-Cycle Cost Analysis and Design of Civil Infrastructures Systems, eds. A.S. Nowak and Dan M. Frangopol, Cocoa Beach, Florida, USA, May 8-11, 2005, pp. 325-333.