Weathering steel is commonly used as a cost-effective alternative for bridge superstructures, as the costs and environmental impacts associated with the maintenance/replacement of paint coatings are theoretically eliminated. The performance of weathering steel depends on the proper formation of a surface patina, which consists of a dense layer of corrosion product used to protect the steel from further atmospheric corrosion. The development of the weathering steel patina may be hindered by environmental factors such as humid environments, wetting/drying cycles, sheltering, exposure to de-icing chlorides, and design details that permit water to pond on steel surfaces. Weathering steel bridges constructed over or adjacent to other roadways could be subjected to sufficient salt spray that would impede the development of an adequate patina. Addressing areas of corrosion on a weathering steel bridge superstructure where a protective patina has not formed is often costly and negates the anticipated cost savings for this type of steel superstructure. Early detection of weathering steel corrosion is important to extending the service life of the bridge structure; however, written inspection procedures are not available for inspectors to evaluate the performance or quality of the patina. This project focused on the evaluation of weathering steel bridge structures, including possible methods to assess the quality of the weathering steel patina and to properly maintain the quality of the patina. The objectives of this project are summarized as follows: -- Identify weathering steel bridge structures that would be most vulnerable to chloride contamination, based on location, exposure, environment, and other factors. -- Identify locations on an individual weathering steel bridge structure that would be most susceptible to chloride contamination, such as below joints, splash/spray zones, and areas of ponding water or debris. -- Identify possible testing methods and/or inspection techniques for inspectors to evaluate the quality of the weathering steel patina at locations discussed above. -- Identify possible methods to measure and evaluate the level of chloride contamination at the locations discussed above. -- Evaluate the effectiveness of water washing on removing chlorides from the weathering steel patina. -- Develop a general prioritization for the washing of bridge structures based on the structure's location, environment, inspection observations, patina evaluation findings, and chloride test results.

Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations contains lectures and papers presented at the Tenth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020), held in Sapporo, Hokkaido, Japan, April 11–15, 2021. This volume consists of a book of extended abstracts and a USB card containing the full papers of 571 contributions presented at IABMAS 2020, including the T.Y. Lin Lecture, 9 Keynote Lectures, and 561 technical papers from 40 countries. The contributions presented at IABMAS 2020 deal with the state of the art as well as emerging concepts and innovative applications related to the main aspects of maintenance, safety, management, life-cycle sustainability and technological innovations of bridges. Major topics include: advanced bridge design, construction and maintenance approaches, safety, reliability and risk evaluation, life-cycle management, life-cycle sustainability, standardization, analytical models, bridge management systems, service life prediction, maintenance and management strategies, structural health monitoring, non-destructive testing and field testing, safety, resilience, robustness and redundancy, durability enhancement, repair and rehabilitation, fatigue and corrosion, extreme loads, and application of information and computer technology and artificial intelligence for bridges, among others. This volume provides both an up-to-date overview of the field of bridge engineering and significant contributions to the process of making more rational decisions on maintenance, safety, management, life-cycle sustainability and technological innovations of bridges for the purpose of enhancing the welfare of society. The Editors hope that these Proceedings will serve as a valuable reference to all concerned with bridge structure and infrastructure systems, including engineers, researchers, academics and students from all areas of bridge engineering.

Life-Cycle Civil Engineering: Innovation, Theory and Practice contains the lectures and papers presented at IALCCE2020, the Seventh International Symposium on Life-Cycle Civil Engineering, held in Shanghai, China, October 27-30, 2020. It consists of a book of extended abstracts and a USB card containing the full papers of 230 contributions, including the Fazlur R. Khan lecture, eight keynote lectures, and 221 technical papers from all over the world. All major aspects of life-cycle engineering are addressed, with special emphasis on life-cycle design, assessment, maintenance and management of structures and infrastructure systems under various deterioration mechanisms due to various environmental hazards. It is expected that the proceedings of IALCCE2020 will serve as a valuable reference to anyone interested in life-cycle of civil infrastructure systems, including students, researchers, engineers and practitioners from all areas of engineering and industry.

Weathering steel is a high-strength, low-alloy steel which has been proven to provide a significantly higher corrosion resistance than regular carbon steel. This corrosion resistance is a product of the small amounts of alloying elements added to the steel, which enable it to form a protective oxide layer when exposed to the environment. The main advantage of its use in bridges is that, under normal conditions, it may be left unpainted, leading to significantly reduced maintenance and environmental costs. Weathering steel has been a material of choice for highway structures for almost half a century, and a very large number of structures have been constructed with it. Although its use has for the most part been successful, it has also become evident that, in circumstances where there is the presence of salt and sulphur oxides, its performance is deficient. In these situations the corrosion penetration rate is much higher than expected, and the oxide layer forms in thick layers. This presents an added risk, since these layers flake off and fall onto the roadway. The degree of corrosion on structures can be very different, even if the structural type, location, and climate are similar. Therefore the focus of the thesis is on the lifespan of weathering steel highway structures. Primarily this research is concerned with the effect of corrosion on the integrity of these structures, as well as ways of quantifying corrosion loss and protecting the structure from further corrosion. In order to determine the lifespan of weathering steel highway structures subject to different rates of corrosion, a probabilistic structural analysis program has been developed to assess the time-dependent reliability of the structure. This program used iterative Monte Carlo simulation and a series of statistical variables relating to the material, loading, and corrosion properties of the structure. A corrosion penetration equation is used to estimate thickness loss at a selected interval, and the structural properties of the bridge are modified accordingly. The ultimate limit states of shear, moment, and bearing, and the fatigue limit state of web breathing, are taken into account. Three types of structures are examined: simply-supported box and I-girder composite bridges, and a two-span box girder bridge. Based on the structural analysis of the corroding bridge structures presented herein, it can be seen that corrosion to the weathering steel girders can cause reduced service lives of the structures. I-girder bridges are shown to be more susceptible to corrosion than box girder bridges, with continuous box girder bridges showing the best performance. The amount of truck traffic does not affect the reliability of the bridge. The short-span and high strength steel bridges are more susceptible to corrosion loss, primarily because their girders have thinner sections. A two-lane bridge also has better performance than the wider bridges because the weight of the barriers and sidewalks is carried by fewer girders, so these girders are stockier. The web breathing limit state is less significant than the combined ultimate limit states. Lastly, and most importantly, inspection data from a highway bridge is used to demonstrate the benefit that can be derived from using field data to update the time-dependent reliability. The ultrasonic thickness gauge (UTG) is a common tool for thickness measurement of steel sections. When used to measure weathering steel, this instrument provides accurate data about the depth of corrosion pits, but not their lateral dimensions. The measurement does not include the corrosion layer on the opposite side of the plate from the one being measured; however, if the corrosion layer is on the measured face, a disproportionate increase in the measured thickness can be seen. In order to prevent or minimize corrosion loss, the steel is currently painted, a process with several environmental and financial disadvantages. Therefore, three novel protection methods have been assessed in a cyclic corrosion test: a zinc metallizing, an aluminum-zinc-indium alloy metallizing, and a zinc tape with a PVC topcoat. All these coatings are designed to act not just as barriers, but also as sacrificial anodes. The test was run for 212 24-hr cycles, over the course of which the all the coatings were proven effective at protecting the steel substrate, regardless of steel type and surface roughness and pretreatment. In conclusion, the threat to all types of weathering steel highway structures by contaminant-induced corrosion is significant, but inspection data permits a more accurate prediction of time-dependent reliability for a structure, and protective coatings are a promising method of slowing the advance of corrosion.

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 354: Inspection and Management of Bridges with Fracture-Critical Details explores the inspection and maintenance of bridges with fracture-critical members (FCMs), as defined in the American Association of State Highway and Transportation Officials' Load and Resistance Factor Design (LRFD) Bridge Design Specifications. The report identifies gaps in literature related to the subject; determines practices and problems with how bridge owners define, identify, document, inspect, and manage bridges with fracture-critical details; and identifies specific research needs. Among the areas examined in the report are inspection frequencies and procedures; methods for calculating remaining fatigue life; qualification, availability, and training of inspectors; cost of inspection programs; instances where inspection programs prevented failures; retrofit techniques; fabrication methods and inspections; and experience with fracture-critical members fractures and problems details.

This report presents findings of a survey and laboratory evaluation of materials and techniques for cleaning and painting chloride-contaminated weathering steel bridges. Laboratory techniques suitable for field usage were developed for assessing the conductivity and chloride level of prepared surfaces. The following cleaning techniques were evaluated for their effectiveness in removing chloride from corroded and pitted plates: air abrasive wet blasting, dry blasting (including alternative abrasives), dry blast and rinse sequences, pressurized water jetting, power tool cleaning, hand tool cleaning, and chemical strippers. Eight coating systems, including organic and inorganic zinc, high-solids epoxies, thermal spray zinc, oil/alkyd, and petroleum wax were selected for laboratory evaluations. They were applied over laboratory and bridge specimens of weathering steel having various levels of chloride contamination using four preparation techniques: wet and dry blasting, power tool and hand tool cleaning. The coatings were exposed to salt spray, immersion in deionized water, and a composite test incorporating ultraviolet radiation, condensation, and freeze-thaw conditions. Based on these tests, and other considerations, the four surface preparation techniques and the following eight systems were selected for multisite 5-year bridge and test fence evaluation: epoxy zinc-rich, urethane zinc-rich, epoxy mastic, thermal spray zinc, three inorganic zincs (conventional and low-VOC ethyl silicate, and water-borne alkali silicate) and oil-alkyd control. Preliminary guidelines were developed for weathering steel maintenance options of no painting, painting corroded areas only, and painting entire structure.

Transportation infrastructure is the backbone of American commerce & industry at the advent of the 21st century. Bridges are the key elements of the transportation system of a country. According to National Bridge Inventory 2005, there are approximately six hundred thousand bridges in United States, among them nearly one third of bridges are functionally obsolete. A lack in performance of such structures, with respect to minimum acceptable standards, has direct impact not only on the highway system but also on public safety as well as economic growth. Systematic and well-designed research will provide the most effective approach to the solution of many problems facing by the highway administrators and engineers. This research describes the various factors that accelerate the deterioration of steel bridges and its repair methods. In addition, this research studies several bridges to collect the required data for the development of model, which is initial stage of database design. The collected data is normalized into third normal form. Finally, a theoretical model and a suitable database for steel bridge repair, inspection and maintenance was designed. The database is designed with the help of Microsoft Access, SQL and Visual Basic Net. The developed database able to store, edit and generate reports according to the user choices.

This report describes a 4-year bridge and test fence evaluation of protective coatings for maintaining weathering steel bridges. The test specimens consisted of steel panels cut from existing aged weathering steel bridges, along with some new mill scale bearing weathering steel as a control. The condition of the specimens ranged from extensively pitted and corroded (from chloride exposure) to mildly corroded and non-pitted. Specimens were cut from angle irons, stiffeners, cover plates, and web areas of bridges. Three methods of surface preparation were used: dry abrasive blasting, wet abrasive blasting, and power tool cleaning using rotary peening and non-woven abrasive discs.

The purpose of this project was to identify efficient and cost-effective methodologies for maintenance painting of steel bridges for MnDOT bridge crews to extend the service life of the coating system by at least five years before complete coating rehabilitation would be warranted. Five generic coating systems, chosen for their compatibility with existing MnDOT coating systems and minimal requirements for surface preparation and application, were applied over minimally prepared surfaces on two St. Paul bridges. Coating performance was evaluated annually over a three-year period through visual field observation following the MnDOT Steel Bridge Coating Condition Assessment Photographic Field Guide and MnDOT Bridge and Structure Inspection Program Manual. Adhesion testing was performed in accordance with ASTM D3359 in conjunction with the third-year evaluation. The results were photographed and documented in a matrix, identifying key performance characteristics. The predominant failure affecting two of the coating systems was delamination due to application over an anti-graffiti finish coat. Otherwise, each system performed to a standard aligning with the pre-established project goal for expanded serviceability of five years. Because developing a Bridge Maintenance Coating Program requires critical timing in the inspection process to identify existing coating condition, a Bridge Coating Repair Reference Table was developed to assist MnDOT crews with determining the appropriate preventive maintenance painting strategy based on condition and existing coating system. This work also determined that surface conditions demonstrating pitting with rusting, or surfaces with an anti-graffiti coating should not be addressed through maintenance painting but instead should be considered for coating removal and replacement.