Cost-effectiveness evaluation of design criteria

A systematic approach is proposed for evaluating the cost-effectiveness of existing or proposed design criteria from the standpoint of life-cycle cost consideration. Following the procedure of a given design code, a typical structure, representing a particular class of system, would be designed for varying levels of safety or reliability under a specified loading. The initial cost of each of the designs may then be estimated, covering the costs of design, material, and construction. The potential damage/repair cost over the life of each of the designs would include the cost of maintenance and repair, the loss of contents, the cost of injuries and loss of lives, and economic losses. The latter must be expressed in terms of present worth. The various initial costs and expected damage/repair costs constitute the expected life-cycle costs of the respective designs. The design with the minimum expected lifecycle cost may then be identified; its underlying safety or reliability can also be determined. The approach is illustrated for a class of reinforced concrete buildings under earthquake loading. For this case, the cost optimal design is compared with the corresponding design obtained with a very small annual acceptable risk of death(of order 10(-8)).