Life Cycle Costing.

Most bridge management systems have been developed to support either network- or project-level decisions. Network-level decisions include the selection of bridges for repair while repair strategies are considered project-level decisions. This article introduces an integrated model for bridge deck repairs with detailed life cycle costs of both network-level and project-level decisions. Two evolutionary-based optimization techniques that are capable of handling large-size problems, namely genetic algorithms and shuffled frog leaping, are then applied on the model to optimize maintenance and repair decisions. Ten trial runs with different numbers of bridges were used to compare the results of both techniques. The results indicate that both techniques can be equally suitable, and that the key issue is determining the set of parameters that optimize performance. The best optimization strategy for this type of problem appears to be a year-by-year strategy coupled with the use of a preprocessing function to allocate repair funds first to critical bridges.

Comparison of Two Evolutionary Algorithms for Optimization of Bridge Deck Repairs

The optimal decisions to maintain or improve the reliability and functionality of structures and infrastructure systems can only be achieved through proper integrated management planning in a life-cycle comprehensive framework. Structure and Infrastructure Engineering (SIE) is an international journal dedicated to recent advances inmaintenance, management, and life-cycle performance of a wide range of infrastructures. The purpose of this article is to provide a brief review of the recent research accomplishments in the field of design, maintenance, life-cycle management, and optimisation of structures and infrastructures reported in papers published in SIE during the period 2005–2011. The papers are categorised under main topics and very briefly discussed.

Maintenance, management, life-cycle design and performance of structures and infrastructures: a brief review

The performance of structures and infrastructure under natural hazards can have a significant impact on the sustainability of the system, often characterized in terms of environmental, economic, or social indicators of performance. This paper commences with a brief review of the relation of natural hazard performance to sustainability and an assessment of bridge infrastructure sustainability with an emphasis on environmental indicators. A framework for life cycle sustainability analysis (LCS-A) is then posed that elucidates the role of natural hazard risks when evaluating sustainable bridge performance using risk-based indicators of environmental sustainability, including embodied energy and carbon dioxide (CO2) emissions. Its application provides insight on the sustainability of mitigating damage from natural hazards through retrofitting deficient structures, considering uncertainty in the hazard occurrence, structural performance, and repair or reconstruction actions that affect energy expenditu...

Sustainability of Natural Hazard Risk Mitigation: Life Cycle Analysis of Environmental Indicators for Bridge Infrastructure

Bridge management systems can be classified as one of two types: network level or project level. The former type is concerned with the prioritization of bridges for inclusion in an upcoming maintenance, repair, and rehabilitation program, and the latter focuses on the repairs that suit the components of a selected bridge. Even though these types are interrelated, most bridge management research treats them as separate aspects. A comprehensive framework is presented for a bridge deck management system that aims at integrating project-and network-level decisions into a unified model to optimize costs at both levels. The novelty of the proposed approach stems from three main aspects: incorporating project-level repair options along with their performance improvements and cost implications; incorporating many flexible and practical features such as variable yearly budget limits, variable yearly discount rates, and optional methods for handling project-level repairs (e.g., single or multiple visits); and using...

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Bridge Deck Management System with Integrated Life-Cycle Cost Optimization

Whether the increasingly poor performance of transportation infrastructure, the budget shortfalls many owners are facing, or the increased demand for more accountability are considered, it is clear that a revolution related to the management of transportation infrastructure is long overdue. There is a broad consensus that this revolution will take shape through adapting and transitioning to the paradigm of asset management (AM). This paper firstly reviews the concept of AM applied to transportation infrastructure, identifies key attributes, and provides a brief overview of the on-going and planned transition to AM by two transportation agencies. Secondly, this paper provides an overview of the related paradigms of performance-based engineering, lifecycle cost analysis, and structural health monitoring, and their role within an integrated AM system. Finally, this paper identifies and discusses relevant issues that transportation infrastructure owners face when they embark on a transition to AM, and propose...

Governing issues and alternate resolutions for a highway transportation agency's transition to asset management

This paper aims to evaluate the effects of seismic risk on life-cycle cost (LCC) analysis for bridge maintenance. With a focus on deterioration due to corrosion of steel from chloride attack, LCC is examined for reinforced concrete (RC) bridge piers by consideration of the uncertainties emanating from earthquakes. Seismic risk is defined in terms of the seismic loss calculated by the earthquake motion with random quantities. Next, LCC is determined using the seismic loss, by which optimal maintenance plans are obtained using a genetic algorithm. It is concluded, based on numerical computations, that: 1) considering the seismic risk, it is possible to evaluate the effects of earthquake retrofitting methods; 2) the seismic risk greatly affects the selection of repair methods; and 3) the initial seismic performance is very important to establish earthquake resistant design.

Effects of Seismic Risk on Life-Cycle Cost Analysis for Bridge Maintenance

The aim of this paper is to develop an appropriate decision supporting system for planning the rational maintenance scheduling of reinforced concrete (RC) decks, which are one of the structural elements composing steel highway bridges. The paper places emphasis on how to appropriately decide the repair order for some deteriorating RC decks among many existing highway bridges and the paper also takes into account the traffic characteristics of road network and the environmental conditions at the construction sites. The concept of life cycle cost analysis is applied in order to evaluate the fitness of repair method for the damaged RC decks. A Genetic Algorithm (GA) is used to search for a practical and rational combinatorial optimization solution for the maintenance problem because GA has such an advantage that it can provide us with useful solutions for large and complex combinatorial scheduling problems with discontinuous or vague objective functions.

Optimal Maintenance Planning of Reinforced Concrete Decks on Highway Network

Many existing bridges in Japan are suffering from damage due to the deterioration of materials, heavy traffics and aging. In the future, it is evident that serious social problems will arise as the number of damaged bridges increases. Considering the present social and economic situation of Japan, it is urgent and important to establish an optimal maintenance strategy for such existing bridges so as to ensure their safety in satisfactory levels. Life-Cycle Cost (LCC) has been paid attention as a possible and promising method to archive a rational maintenance program. Generally, LCC consists of initial cost, maintenance cost, and renewal cost. However, when considering Life-Cycle Cost in the region that frequent earthquakes occur, it is important to take into account the social and economical effects due to the collapse of structures as well as the minimization of maintenance cost. The loss by the collapse of structures due to the earthquakes can be defined in terms of an expected cost and introduced into the calculation of LCC. In this study, a stochastic model of structural response is proposed, which accounts for the variation due to the uncertain characteristics of earthquakes, and the probability of failure is calculated based on the reliability theory. Then, the expected cost can be obtained by multiplying the failure probability with the loss.

Life-Cycle Cost for Bridge Structures Considering Earthquake Effects

近年, 橋梁の景観設計の重要性が広く認識されてきていることと, 住民参加型の社会資本形成の広がり, さらにその利用者の感性を取り込んだ設計が求められるようになってきている. 本論文では, 商品開発などで成果をあげている感性工学手法を取りあげ, 桁橋を対象に利用者の中でも大学生によるアンケート調査を行い, 学生が橋に対して要求している感性を分析し, 桁橋を構成するデザイン要素と感性との関係を合理的に結び付けることを試みた. そして, これまで橋梁の景観評価に有効であるとしてよく用いられてきたニューラルネットワークとの比較を行うことで, 今後の新しい景観評価・設計の方向性として感性工学手法の有用性を明らかにする.

Masahiro Dogaki

Papers

Governing issues and alternate resolutions for a highway transportation agency's transition to asset management

Effects of Seismic Risk on Life-Cycle Cost Analysis for Bridge Maintenance

Optimal Maintenance Planning of Reinforced Concrete Decks on Highway Network

Life-Cycle Cost for Bridge Structures Considering Earthquake Effects

A study on assessment and design of aesthetics with girder bridge using kansei engineering method