Generally, for projects with rehabilitation alternatives that have differing and significant future costs, rehabilitation alternatives are commonly evaluated using life-cycle cost method. In addition, practically, for a bridge, a retrofitting strategy is determined only by the specified performance and corresponding direct costs. However, in most retrofitting cases, the indirect costs or social impacts of potential retrofitting methods, which probably influence the selected retrofitting strategy, are not considered. For a bridge, its columns or piers, which are the main seismically resistant members of the bridge, are retrofitted to improve seismic performance. Additionally, the seismic retrofitting of bridge columns can significantly improve its structural ductility or strength. However, retrofitting may cause unexpected damage to the non-retrofitted components/members. Therefore, a corresponding retrofitting of these components/members should be considered as part of any retrofitting method to eliminate unexpected damage. For determining an appropriate retrofitting method of a reinforced concrete bridge, this work presents a method for calculating the relationship between the resilience in functionality and seismic intensity that is achieved using a particular retrofit method. The system reliability and recovery time of each damaged component/member are considered in the resilience analysis. Furthermore, the benefit-to-cost ratio, based on the resilience index, the potential costs of the retrofit method and life-cycle cost of various earthquake events in a given time-window, are evaluated to develop appropriate retrofit strategies. In the end, two bridges in Taipei are selected herein to provide an example of the application of the proposed quantification method to identify an appropriate retrofit method based on the Benefit-cost ratio.

Generally, for projects with rehabilitation alternatives that have differing and significant future costs, rehabilitation alternatives are commonly evaluated using life-cycle cost method. In addition, practically, for a bridge, a retrofitting strategy is determined only by the specified performance and corresponding direct costs. However, in most retrofitting cases, the indirect costs or social impacts of potential retrofitting methods, which probably influence the selected retrofitting strategy, are not considered. For a bridge, its columns or piers, which are the main seismically resistant members of the bridge, are retrofitted to improve seismic performance. Additionally, the seismic retrofitting of bridge columns can significantly improve its structural ductility or strength. However, retrofitting may cause unexpected damage to the non-retrofitted components/members. Therefore, a corresponding retrofitting of these components/members should be considered as part of any retrofitting method to eliminate unexpected damage. For determining an appropriate retrofitting method of a reinforced concrete bridge, this work presents a method for calculating the relationship between the resilience in functionality and seismic intensity that is achieved using a particular retrofit method. The system reliability and recovery time of each damaged component/member are considered in the resilience analysis. Furthermore, the benefit-to-cost ratio, based on the resilience index, the potential costs of the retrofit method and life-cycle cost of various earthquake events in a given time-window, are evaluated to develop appropriate retrofit strategies. In the end, two bridges in Taipei are selected herein to provide an example of the application of the proposed quantification method to identify an appropriate retrofit method based on the Benefit-cost ratio.

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