Guardrails for Use on Historic Bridges: Volume 2—Bridge Deck Overhang Design

Bridges that are designated historic present a special challenge to bridge engineers whenever rehabilitation work or improvements are made to the bridges. Federal and state laws protect historically significant bridges, and railings on these bridges can be subject to protection because of the role they play in aesthetics. Unfortunately, original railings on historic bridges do not typically meet current crash-test requirements and typically do not meet current standards for railing height and size of permitted openings. The primary objective of this study is to develop strategies that can be used to address existing railings on historic bridges and to develop solutions that meet current design requirements. In addition to the modification, selection, and design of the bridge railing, the bridge deck is also impacted by changes made to the railing. Due to increased force levels recently required by AASHTO, deck overhangs require significantly more reinforcement than for past practice. These increases are being realized on all bridge decks and may pose particular challenges for the attachment of railing to historic bridges. Therefore, a secondary objective of this project is to investigate the design of the deck overhang and determine whether reduced amounts of reinforcement are possible. For Volume 1 (Replacement Strategies), three phases of research were conducted. First, an overview of current practice for addressing historic bridge railings was performed. Second, an investigation was conducted to document historic bridge railings in Indiana. Finally, rehabilitation solutions were developed to address the specific bridge railings found in Indiana. Based on this research, three retrofit strategies were developed which include an inboard railing, curb railing, and a simulated historic railing. These rehabilitation solutions can be used to address historic bridge railings not only in Indiana, but across the country. For Volume 2 (Bridge Deck Overhang Design), experimental testing of half-scale and full-scale overhang specimens was conducted, and the results were analyzed. Failures of in-service bridge railings were also evaluated. Based on this research, recommendations are provided for the more efficient and economic design of bridge deck overhangs. These recommendations are applicable not only for historic bridges, but for all concrete bridge decks

Implementation of a Non-Metallic Reinforced Bridge Deck, Volume 1: Bond Behavior

The primary maintenance problem with bridges in Indiana has been deterioration of the concrete deck which is often related to corrosion of the reinforcing steel. While a corrosion protection system consisting of epoxy-coated reinforcement in combination with 2-1/2 in. of Class C concrete cover has been used in Indiana, research and experience have demonstrated that this system can be compromised. As an alternative solution to the corrosion problem in reinforced concrete, fiber reinforced polymer (FRP) bars which are corrosion resistant can be provided as reinforcement. This research was divided into two phases directed towards the implementation of a nonmetallic reinforced bridge deck. The first phase evaluated the bond strength of fiber reinforced polymer reinforcement with the goal of developing a design expression for the calculation of development and splice lengths. Forty-six glass FRP, carbon FRP, and steel reinforced concrete beams with unconfined tension lap splices were tested. The second phase consisted of the design, construction, and performance evaluation of a glass FRP bar reinforced concrete bridge deck. Based on this study, design recommendations are provided for the calculation of development and splice lengths of both FRP and steel reinforcement. Furthermore, the behavior of the FRP reinforced bridge deck is assessed and compared with its design assumptions. The findings of this study provide design tools and behavioral data that will assist in the future development and deployment of this technology

Reduction of Bridge Construction and Maintenance Costs through Coupled Geotechnical and Structural Design of Integral Abutment Bridges

Elimination expansion joints in the superstructure of integral abutment bridges offers the advantage of reducing the initial and life cycle costs of the structure. However, such elimination may have an adverse effect on the displacement demand at the pile-abutment connection and on the earth pressures on the abutment wall due to the thermal expansion/contraction cycles of the bridge. These adverse effects have resulted in regulations that impose restrictions on the maximum length and skew angle of integral abutment bridges. This research consisted of a deep analysis of the problem by considering soil-structure interaction. The approach was multifaceted as it included experimental and numerical analysis. Upon calibration and verification of the constitutive model, it was used as part of a parametric analysis to provide recommendations for the design limits of integral abutment bridges. The analysis results showed that active state earth pressure is reached after the first contraction cycle. The displacement demand on piles is a function of the abutment wall displacement. Larger displacement demand of the pile at the acute corner when compared to the obtuse corner was observed during expansion and contraction cycles. The inflection point of the piles deformed shape was found to be at relatively shallow depth. Concrete shrinkage and sequence of loading affected significantly the displacement demand of the supporting piles, lower displacement demand of piles during the expansion cycle and larger displacement demand during contraction cycles. The analysis showed that a 500 ft bridge with 60° skew will provide acceptable long term performance

Increasing Bridge Deck Service Life: Volume I—Technical Evaluation

Deterioration of bridge decks is a primary factor limiting the lifespan of bridges especially in cold climates where deicing salts are commonly used. While controlling deck cracking or decreasing the permeability and porosity of concrete can improve performance and service life, chloride and moisture ingress as well as cracking cannot be eliminated. Full-depth cracks which are caused by restrained shrinkage allow for corrosive conditions at early ages for both the top and bottom reinforcement mats. Therefore, the use of corrosion-resistant reinforcement is essential to mitigate deterioration of bridge decks. The objective of this research program to examine the efficacy of using alternative materials in a bridge deck from both technical and economic perspectives. For the technical evaluation (Volume I), a three phase experimental investigation was conducted considering a wide range of corrosion-resistant reinforcing materials. These materials included stainless steels, microcomposite steel, and coated steels considering a variety of metallic and nonmetallic coatings. The first phase evaluated the bond between corrosion-resistant reinforcement and concrete using lap splice tests. The second phase evaluated the cracking behavior of slabs reinforced with corrosion-resistant reinforcement. Finally, the third phase evaluated corrosion resistance under uncracked and cracked conditions using macrocell test specimens. Transverse steel was also tied to the longitudinal steel to simulate actual bridge deck conditions. Recommendations are provided on development and splice lengths for both conventional black and corrosion-resistant reinforcing steel, control of cracks widths, as well as the selection, design, and construction of corrosion-resistant reinforcement. For the economic evaluation (Volume II), a decision support methodology and associated spreadsheet tool for robust analysis of the cost-effectiveness of alternative material types for bridge deck reinforcement was developed. The two evaluation criteria are agency and user costs, and the input data that influence this criteria include the deck service life, material process, discount rate, detour length, and bridge size. The methodology incorporates analytical techniques that include life cycle analyses to evaluate the long-term cost and benefits of each material over the bridge life; Monte Carlo simulation to account for the probabilistic nature of the input variables; stochastic dominance to ascertain the probability distribution of the outcome that a specific reinforcement material is superior to others; and analytical hierarchical process to establish appropriate weights for the agency and user costs. The study methodology is demonstrated using a case study involving three reinforcement material alternatives: traditional (epoxy-coated) steel, zinc-clad steel, and stainless steel. Through this study, it is demonstrated that the use of corrosion-resistant reinforcing materials can significantly increase bridge deck life, reduce agency and user costs associated with bridge deck rehabilitation and maintenance, and thus lower the financial needs for long-term preservation of bridges

Guardrails for Use on Historic Bridges: Volume 1—Replacement Strategies

Bridges that are designated historic present a special challenge to bridge engineers whenever rehabilitation work or improvements are made to the bridges. Federal and state laws protect historically significant bridges, and railings on these bridges can be subject to protection because of the role they play in aesthetics. Unfortunately, original railings on historic bridges do not typically meet current crash-test requirements and typically do not meet current standards for railing height and size of permitted openings. The primary objective of this study is to develop strategies that can be used to address existing railings on historic bridges and to develop solutions that meet current design requirements. In addition to the modification, selection, and design of the bridge railing, the bridge deck is also impacted by changes made to the railing. Due to increased force levels recently required by AASHTO, deck overhangs require significantly more reinforcement than for past practice. These increases are being realized on all bridge decks and may pose particular challenges for the attachment of railing to historic bridges. Therefore, a secondary objective of this project is to investigate the design of the deck overhang and determine whether reduced amounts of reinforcement are possible. For Volume 1 (Replacement Strategies), three phases of research were conducted. First, an overview of current practice for addressing historic bridge railings was performed. Second, an investigation was conducted to document historic bridge railings in Indiana. Finally, rehabilitation solutions were developed to address the specific bridge railings found in Indiana. Based on this research, three retrofit strategies were developed which include an inboard railing, curb railing, and a simulated historic railing. These rehabilitation solutions can be used to address historic bridge railings not only in Indiana, but across the country. For Volume 2 (Bridge Deck Overhang Design), experimental testing of half-scale and full-scale overhang specimens was conducted, and the results were analyzed. Failures of in-service bridge railings were also evaluated. Based on this research, recommendations are provided for the more efficient and economic design of bridge deck overhangs. These recommendations are applicable not only for historic bridges, but for all concrete bridge decks

Development and Splice Lengths for High-Strength Reinforcement, Volume I: General Bar Development

To support the adoption of high-strength reinforcement (fy \u3e 60 ksi) into widespread use, it is fundamental that appropriate development and splice lengths be calculated. The objective of this research is to evaluate the development of high-strength reinforcing steel and establish a design expression for the development and splicing of this steel. Two phases of experimental tests were conducted along with analytical evaluation. Based on the research, a design expression was developed that will enable appropriate design and detailing of concrete structures containing high-strength reinforcement

Performance-Related Specifications for Concrete Bridge Superstructures, Volume 3: Nonmetallic Reinforcement

In Volume 3 of the final report, research work conducted to investigate the behavior of fiber reinforced polymer (FRP) reinforcement is summarized. This study focused on the behavior of FRP reinforced concrete structures with an emphasis on bond and shear. For the bond investigation, three series of beam splice tests were performed on specimens reinforced with steel, glass FRP, and aramid FRP to determine the effect of the different types of reinforcement on bond, cracking, and deflections. The test results indicate that the use of FRP reinforcement leads to lower bond strengths and, therefore, require longer development lengths. The specimen crack widths and deflections were substantially larger for FRP specimens than steel specimens due to the significantly lower modulus of elasticity. Analysis of the test results resulted in recommendations for modifying the empirical development length equation of ACI 318- 99 design code for use with FRP reinforcement. For the shear investigation, two series of beam tests were conducted on specimens reinforced with steel, glass FRP, and aramid FRP to determine the effect of the different types of reinforcement on the concrete shear strength. All specimens did not contain transverse reinforcement. The test results indicate that the use of FRP reinforcement leads to lower concrete shear strengths than steel reinforcement for equal reinforcement cross-sectional areas (longitudinal reinforcement percentages). Analysis of the test results resulted in recommendations for the calculation of concrete shear strength. Based on the findings of this research, design and construction recommendations are provided that can be used for the design and construction of FRP reinforced bridge decks

Increasing Bridge Deck Service Life: Volume II—Economic Evaluation

Deterioration of bridge decks is a primary factor limiting the lifespan of bridges especially in cold climates where deicing salts are commonly used. While controlling deck cracking or decreasing the permeability and porosity of concrete can improve performance and service life, chloride and moisture ingress as well as cracking cannot be eliminated. Full-depth cracks which are caused by restrained shrinkage allow for corrosive conditions at early ages for both the top and bottom reinforcement mats. Therefore, the use of corrosion-resistant reinforcement is essential to mitigate deterioration of bridge decks. The objective of this research program to examine the efficacy of using alternative materials in a bridge deck from both technical and economic perspectives. For the technical evaluation (Volume I), a three phase experimental investigation was conducted considering a wide range of corrosion-resistant reinforcing materials. These materials included stainless steels, microcomposite steel, and coated steels considering a variety of metallic and nonmetallic coatings. The first phase evaluated the bond between corrosion-resistant reinforcement and concrete using lap splice tests. The second phase evaluated the cracking behavior of slabs reinforced with corrosion-resistant reinforcement. Finally, the third phase evaluated corrosion resistance under uncracked and cracked conditions using macrocell test specimens. Transverse steel was also tied to the longitudinal steel to simulate actual bridge deck conditions. Recommendations are provided on development and splice lengths for both conventional black and corrosion-resistant reinforcing steel, control of cracks widths, as well as the selection, design, and construction of corrosion-resistant reinforcement. For the economic evaluation (Volume II), a decision support methodology and associated spreadsheet tool for robust analysis of the cost-effectiveness of alternative material types for bridge deck reinforcement was developed. The two evaluation criteria are agency and user costs, and the input data that influence this criteria include the deck service life, material process, discount rate, detour length, and bridge size. The methodology incorporates analytical techniques that include life cycle analyses to evaluate the long-term cost and benefits of each material over the bridge life; Monte Carlo simulation to account for the probabilistic nature of the input variables; stochastic dominance to ascertain the probability distribution of the outcome that a specific reinforcement material is superior to others; and analytical hierarchical process to establish appropriate weights for the agency and user costs. The study methodology is demonstrated using a case study involving three reinforcement material alternatives: traditional (epoxy-coated) steel, zinc-clad steel, and stainless steel. Through this study, it is demonstrated that the use of corrosion-resistant reinforcing materials can significantly increase bridge deck life, reduce agency and user costs associated with bridge deck rehabilitation and maintenance, and thus lower the financial needs for long-term preservation of bridges

Repair and Strengthening of Bridges in Indiana Using Fiber Reinforced Polymer Systems: Volume 2–FRP Flexural Strengthening and End Region Repair Experimental Programs

For bridges that are experiencing deterioration, action is needed to ensure the structural performance is adequate for the demands imposed. Innovate repair and strengthening techniques can provide a cost-effective means to efficiently and safely extend the service lives of bridges. The use of fiber reinforced polymer (FRP) systems for the repair and strengthening of concrete bridges is increasing in popularity. Recognizing the potential benefits of the widespread use of FRP, a research project was initiated to determine the most appropriate applications of FRP in Indiana and provide recommendations for the use of FRP in the state for the repair and strengthening of bridges. The details of the research are presented in two volumes. Volume 1 provides the details of a study conducted to (i) summarize the state-of-the-art for the application of FRP to concrete bridges, (ii) identify successful examples of FRP implementation for concrete bridges in the literature and examine past applications of FRP in Indiana through case studies, and (iii) better understand FRP usage and installation procedures in the Midwest and Indiana through industry surveys. Volume 2 presents two experimental programs that were conducted to develop and evaluate various repair and strengthening methodologies used to restore the performance of deteriorated concrete bridge beams. The first program investigated FRP flexural strengthening methods, with focus placed on adjacent box beam bridges. The second experimental program examined potential techniques for repairing deteriorated end regions of prestressed concrete bridge girders. Externally bonded FRP and near-surface-mounted (NSM) FRP were considered in both programs

Concrete Box Beam Risk Assessment and Mitigation: Volume 1—Evolution and Performance

Adjacent box beam bridges have a history of poor long-term performance including premature deterioration and failures. Leaking joints between box beams allow chloride-laden water to migrate through the superstructure and initiate corrosion. The nature of this deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. The objective of this research is to develop recommendations for inspection, load-rating, and design of adjacent box beam bridges. The research is presented in two volumes. Volume 1 focuses on the evolution of box beam design in Indiana to understand the lack of performance and durability. The Indiana Department of Transportation (INDOT) standards and bridge design manuals were reviewed to track the historical development of box beam bridges in the State. Two timelines were produced tracking important updates to box beam design. Adjacent box beam bridges within INDOT’s bridge database were also analyzed. Superstructure ratings were compared with bridge age as well as bridge characteristics to highlight possible causes for deterioration. Analyzing the INDOT inventory, data shows that the condition of adjacent box beam bridges may be affected by location, type of wearing surface, and the use of deck membranes. Six bridges were then inspected to identify common deficiencies and specific problems. Exterior beams and beams within the wheel load path tend to have higher levels of deterioration. Furthermore, leaking joints between beams leads to corrosion of reinforcement, ultimately resulting in spalling, fracture of prestressing strands, and loss of structural capacity. Volume 2 focuses on evaluating the capacity of deteriorated adjacent box beams, the development of improved load rating procedures, and new box beam design. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. Deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedures are provided along with design recommendations for the next generation of box beam bridges