Bridge monitoring and maintenance is an expensive yet essential task in maintaining a safe national transportation infrastructure. Traditional monitoring methods use visual inspection of bridges on a regular basis and often require inspectors to travel to the bridge of concern and determine the deterioration level of the bridge. Automation of this process may result in great monetary savings and can lead to more frequent inspection cycles. One aspect of this automation is the detection of cracks and deterioration of a bridge. This paper provides a comparison of the effectiveness of four crack-detection techniques: fast Haar transform (FHT), fast Fourier transform, Sobel, and Canny. These imaging edge-detection algorithms were implemented in MatLab and simulated using a sample of 50 concrete bridge images (25 with cracks and 25 without). The results show that the FHT was significantly more reliable than the other three edge-detection techniques in identifying cracks.

Analysis of edge-detection techniques for crack identification in bridges

The objective of bridge management is to allocate and use the limited resources to balance lifetime reliability and life-cycle cost in an optimal manner. As the 20th century has drawn to a close, it is appropriate to reflect on the birth and growth of bridge management systems, to examine where they are today, and to predict their future. In this paper, it is attempted to shed some light on the past, present, and future of life-cycle management of highway bridges. It is shown that current bridge management systems have limitations and that these limitations can be overcome by using a reliability-based approach. It is concluded that additional research is required to develop better life-cycle models and tools to quantify the risks, costs, and benefits associated with highway bridges as well as their interrelationships in highway networks.

Reliability-based life-cycle management of highway bridges

https://onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-6143.2003.00011.x

Pooled human gammaglobulin modulates surface molecule expression and induces apoptosis in human B cells.

Life-cycle cost analysis of deteriorating structures has to consider not only time-varying resistance and loading affecting the reliability of these structures but also maintenance interventions applied during their lifetime. Finding the optimum maintenance scenario for a deteriorating structure is a complex process involving the selection of maintenance interventions and their application times associated with minimum life-cycle cost. There is a cost relationship between maintenance intervention cost and the effect of the intervention on system reliability. However, this relationship is not included in modern structural management systems since costs of interventions are prescribed as fixed values independent on their effects on system reliability. Neglecting the interactions among maintenance interventions, their effects on structural performance, and corresponding costs leads to significant limitations of modern management systems for civil infrastructures. In this article, maintenance intervention cost is not considered to be fixed but evaluated dynamically by using cost functions according to time-dependent variables related to the quality of intervention. The main advantages of using cost functions are the flexibility and expandability required for general purpose reliability-based structure management systems. In fact, cost functions can be used in any structure management system based on life-cycle cost. A practical example is provided to show how to establish cost functions of maintenance interventions and how these functions can be used to obtain the optimal life-cycle maintenance scenario.

Cost-Reliability Interaction in Life-Cycle Cost Optimization of Deteriorating Structures

In a world where financial resources do not keep pace with the growing demand for maintenance of deteriorating structures, it is imperative that those responsible for maintenance decisions make the best possible use of limited financial resources. Decision makers have to evaluate the expected life-cycle maintenance cost of deteriorating structures and use benefit/cost techniques for finding the optimal resource allocation. This paper proposes a methodology for the evaluation of expected life-cycle maintenance cost of deteriorating structures by considering uncertainties associated with the application of cyclic maintenance actions. The methodology can be used to determine the expected number of maintenance interventions on a deteriorating structure, or a group of deteriorating structures, during a specified time horizon and the associated expected maintenance costs. The method is suitable for application to both new and existing civil infrastructures under various maintenance strategies. The ultimate objective is to evaluate the costs of alternative maintenance strategies and determine the optimum maintenance regime over a specified time horizon. In its present format, the first line of application of the method is for highway bridges. However, the method can be used for any structure, or group of structures, requiring maintenance in the foreseeable future. The proposed method can be programmed and incorporated into an existing software package for life-cycle costing of civil infrastructures. An existing reinforced concrete bridge stock is analyzed to illustrate the proposed methodology and to reveal the cost-effectiveness of preventive maintenance interventions.

Evaluation of Expected Life-Cycle Maintenance Cost of Deteriorating Structures

Bridge management has been a subject of intense interest and development for the past 10 years. In support of improved bridge management, FHWA funded the development of the Pontis bridge computer program, which is now in use by approximately 40 of the 50 states. In addition, many new guide specifications have been produced to assist bridge managers in their efforts to better manage the nation's aging bridge inventory. The AASHTO Subcommittee on Bridges and Structures has taken the lead along with FHWA in implementing the improved bridge management systems. California and a few other states have been critical of the current ranking system for bridge maintenance and have been working to develop an improved performance measure. The bridge health index (HI), an improved and more comprehensive numerical rating system that uses the element inspection data to determine the remaining asset value of a bridge or network of bridges, is discussed. The HI is more consistent with the element-level evaluation data colle...

Bridge management for the 21st century

There should be no argument that the quality of life and the economic vitality of modern civilizations are dependent on the infrastructures that support them. Of major importance is the transportation system that provides for the transport of goods and services as well as the mobility of the citizens within those civilizations. The enormous investment that Governments have made in highway systems since the 1950's has led the U.S. to be recognized as having the largest and most modern highway system in the world. Within this highway system, bridges are singly the most important link. Without bridges, highway transportation as we know it would cease to exist. In recognition of this, the California Department of Transportation continues to take aggressive actions in the protection of its bridge infrastructure as evidenced by the delivery efforts of the Seismic Retrofit Program and the creation of the Bridge Scour Mitigation Program.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Bridge management for the 21st Century

There should be no argument that the quality of life and the economic vitality of modern civilizations are dependent on the infrastructures that support them. Of major importance is the transportation system that provides for the transport of goods and services as well as the mobility of the citizens within those civilizations. The enormous investment that Governments have made in highway systems since the 1950's has led the U.S. to be recognized as having the largest and most modern highway system in the world. Within this highway system, bridges are singly the most important link. Without bridges, highway transportation as we know it would cease to exist. In recognition of this, the California Department of Transportation continues to take aggressive actions in the protection of its bridge infrastructure as evidenced by the delivery efforts of the Seismic Retrofit Program and the creation of the Bridge Scour Mitigation Program.

Bridge Management for the 21 st Century

This paper describes the seismic retrofit program implemented by the California Department of Transportation after the 1971 San Fernando Earthquake and accelerated after the 1989 Loma Prieta earthquake. The goal of the program is to reinforce most of the bridges designed and constructed prior to acquiring the current levels of knowledge of seismic loading and structure response (about 1978) to improve their structural ductility and resistance to the major factors which contributed to damage and collapse in the San Fernando and Loma Prieta events. The program has been executed in two phases. The initial phase, completed in 1988, provided reinforcement to superstructures of 1260 bridges by connecting all narrow expansion joint seats with hinge restrainers and anchoring girders and other superstructure elements to the substructure. The single and multiple column retrofit phase, now under active implementation, is designed to reinforce substructure elements and create ductile members by increasing confinement. A Risk Analysis procedure was developed to prioritize the bridges for seismic upgrading so that highest risk bridges are retrofitted first. Legislation was recently enacted to require the Department of Transportation to also take the lead role in seismically retrofitting all locally owned bridges in the state. Research has been conducted, and is currently underway, at the University of California, San Diego to test and confirm the validity of several proposed design solutions for seismic retrofitting of existing bridge single column bent substructure elements. Since the Loma Prieta earthquake additional research is being conducted at the University of California at Berkeley, Irvine and Davis to develop and test retrofit techniques for multiple column bents and double level structures, including abutment and footing details. Some full scale testing was completed on a standing portion of the Cypress Street viaduct in Oakland to determine its fundamental response characteristics and to test some techniques which may be applied to the double deck structures in San Francisco and on complex structures with outrigger supports and other non standard support configurations throughout the state.

Recent advances in seismic design and retrofit of bridges

Carter and Burgess, Inc., was selected by the Utah Department of Transportation (UDOT) to evaluate several aspects of the I-15 design-build reconstruction project under way in Salt Lake City. The evaluations are being completed in part to fulfill commitments made to FHWA, which granted a Special Experimental Project 14 status to the I-15 project, permitting design-build contracting methods. Information is presented about the selection process used by UDOT to hire a design-build team to work on the project. UDOT decided to use a "best value" selection process instead of low cost to select a contractor. Comparisons are made between the design-bid-build and design-build processes. Described is the "best value" selection process used by UDOT to evaluate and select a contractor, using the detailed selection process. A description of the organizational structure required to prepare and review the proposals is presented. Unique features of the UDOT process are discussed, including use of stipend, risk sharing, I...

James E. Roberts

Papers

Bridge management for the 21st century

Bridge management for the 21st Century

Bridge Management for the 21 st Century

Recent advances in seismic design and retrofit of bridges

Use of best value selection process: utah department of transportation i-15 design-build project