Annual Rehabilitation Costs Estimation for a Bridge Network

윤유정,Makarand Hastak 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1

The objective of this paper is to present an integrated multi-year rehabilitation planning model (IMRPM) for a bridge network. A multi-year capital program can provide an explicit, steady vision for financial and expenditure strategies as well as improve the efficiency of the allocation of limited resources. Estimating the precise annual rehabilitation needs for sound bridge management is essential to achieving the goals of a multi-year capital program; however, the current rehabilitation planning techniques tend to underestimate the annual rehabilitation costs by overlooking the potential rehabilitation needs which can arise by delaying of Maintenance/Repair (M/R) projects due to insufficient annual funding. The presented model integrates a multi-year rehabilitation capital program into an M/R program within the same multi-year period. The model engages a genetic algorithm for a project-level analysis process to identify M/R and rehabilitation projects over a defined multi-year analysis period (e.g., three, five, or ten years) for each M/R program and rehabilitation program. As a result of this process, the annual rehabilitation costs during a multi-year period initially can be estimated. Then, the initial annual rehabilitation costs can be finalized by including newly-identified rehabilitation needs, which are developed through the annual reanalysis process resulting from the delay of M/R projects in prior years. The annual reanalysis process considers the concept of time floats for M/R projects. The presented model is expected to be useful to efficiently control delayed M/R projects and to provide more reliable estimation for annual rehabilitation needs.

Method for Generating Multiple MRR Solutions for Application in Cost-Leveling Models

Yoon, Yoojung,Hastak, Makarand,Cho, Kyuman American Society of Civil Engineers 2017 Journal of infrastructure systems Vol.23 No.3

<P>Cost-leveling models have been introduced recently to minimize the fluctuations in annual maintenance, repair, and rehabilitation (MRR) costs within a multiyear infrastructure asset-management plan. However, these models were found to produce limited results because they ignored the impacts on all the preceding/succeeding MRR activities in a multiyear plan when the initially identified implementation time of one MRR activity was adjusted for cost-leveling purposes. This paper proposes a method to generate multiple MRR solutions at the facility level for existing cost-leveling models at the network level. The method utilizes two concepts as follows: (1)the fast elitist nondominated sorting genetic algorithm (NSGA-II) to generate a Pareto optimal set of feasible MRR alternatives, and (2)the pseudoweight vector approach with the Euclidean distance and a confidence interval to select multiple MRR solutions from the Pareto optimal set identified by NSGA-II. The proposed method is applied to a sample concrete bridge deck as a case study in this paper; the results show that the proposed method was able to provide multiple MRR solutions having various profiles in terms of the intervention times of the MRR activities and annual MRR costs. Consequently, the proposed method advances the theoretical framework of existing cost-leveling models by combining four approaches to provide multiple MRR solutions at the facility level: (1)NSGA-II algorithm, (2)pseudoweight vector approach, (3)Euclidean distance, and (4)a confidence interval. In addition, it is expected that the proposed method can be well applied to existing multiobjective optimization models to generate a set of nondominated good policies for infrastructure asset management.</P>

Life-cycle cost assessment model for fiber reinforced polymer bridge deck panels

Hong, TaeHoon,Hastak, Makarand Canadian Science Publishing 2007 Canadian journal of civil engineering. Revue canad Vol.34 No.8

<P> To enhance the application of fiber reinforced polymer (FRP) bridge deck panels in the infrastructure area, a practical method is required that would allow probable assessment of the life-cycle cost of advanced composite applications in construction compared with that of conventional materials, at various discount rates, while integrating the available reference data. The overall objective of this research is to develop a performance-based probable life-cycle cost assessment model for FRP bridge deck panels. The life-cycle cost assessment model for FRP bridge deck panels comprises a life-cycle performance module (module-1) and a life-cycle cost optimization module (module-2). The model thus developed in this paper can then be used for other applications of composites in construction. The objective of module-1 is to develop an analytical model that is capable of predicting the structural deterioration over time to assess the deterioration rating per year of FRP bridge deck panels. The objective of module-2 is to develop an analytical model that is capable of assessing the optimal life-cycle cost of FRP bridge deck panels. Three case studies were conducted to validate the logic and results of the process algorithm for the life-cycle cost assessment. The model will be very helpful for the construction industry in evaluating various material options and to justify or deny the feasibility of using composite materials on specific construction projects. Since the life-cycle cost assessment of composite materials in construction has not been dealt with as proposed, it is anticipated that many of the procedures and systems mentioned would include fundamental research and possible innovations.Key words: fiber reinforced materials, Monte Carlo method, life-cycle cost, performance valuation. </P>

Increase in stress on infrastructure facilities due to natural disasters

Juyeong Choi,Abhijeet Deshmukh,Makarand Hastak 서울시립대학교 도시과학연구원 2016 도시과학국제저널 Vol.20 No.2

The services of infrastructure are often compromised in a postdisaster situation. This could be due to a direct physical impact on the infrastructure or due to a cascading impact resulting from reduced services of the supporting infrastructure. The reduced infrastructure services are unable to adequately meet the postdisaster community needs. Therefore, infrastructure facilities are likely to be operated with high stress on their capacities above the allowable stress (i.e. designed capacities) for meeting the services required. The system is unable to sustain the required serviceability level without the infusion of additional capacities when the stress level exceeds the limit stress. For example, after Haiti’s devastating earthquake, disrupted utility services, limited road networks, and the lack of civic governance influenced the capacity of all essential service providers. Furthermore, the earthquake-impacted hospitals had limited resources such as patient beds, medical staff, medical supplies and equipment for meeting the increased health needs of the community. As a result, the hospital experienced increased levels of stress related to services as they were unable to adequately meet the community health needs without external assistance from NGOs or other entities. Therefore, understanding the stress level in postdisaster infrastructure is critical for community recovery. This paper presents a new framework to (i) explore and investigate varying functional stress level in infrastructure under various disaster scenarios and (ii) develop strategies for alleviating increased stress levels in order to facilitate the recovery process. The research framework is explained using a hypothetical situation focusing on the operation of power facilities in a postdisaster situation. The proposed unique approach enables the development of sustainable mitigation strategies by relieving the stress level in critical infrastructure while ensuring to meet recovery demands at an acceptable level.