Search

Many bridge pier caps are deep due to short shear spans. When analyzed using the slender beam theory (i.e., the sectional method), a large number of pier caps are found to be shear-overloaded even though they don't exhibit any noticeable cracking or signs of distress. AASHTO LRFD 2017 recommends the use of either a strut-and-tie or nonlinear finite element model for the analysis and design of deep members. Both methods are more sophisticated and require more effort than the sectional method. The objective of this study was to simplify the strut-and-tie method for pier caps to obtain larger and less conservative shear capacity predictions. For this purpose, a solution algorithm (computer program) was developed based on Section 5.8.2 Strut-and-Tie Method of AASHTO LRFD 2017. The program, named STM-CAP (Strut-and-Tie Method for pier CAPs), is implemented in Microsoft Excel using Visual Basic macro codes. An adaptive graphical solution procedure was employed to minimize the input errors and give the analyst options for optimizing the automatically generated model. STM-CAP calculates the utilization ratio for every element, which reflects the condition (overload or reserve capacity percentage) of the pier cap. If overloaded, STM-CAP indicates the calculated failure mode and its location. Suitable rehabilitation methods and load limits can then be determined accordingly. STM-CAP is verified using a generalpurpose strut-and-tie software, CAST (Computer Aided Strut and Tie) and VecTor2 (a nonlinear finite element analysis software) for eight existing pier caps located in Ohio. In addition, the sectional method calculations were performed to demonstrate the extra shear capacity predictions obtained from the strut-and- tie method. The strut-and-tie method predicted 2 to 3 times higher shear capacities for beams with shear span-to-depth ratio (a/d) of 0.50. The predictions by STM-CAP and the sectional method converge as the a/d ratios approach 3.0. The research results have a potential to result in significant cost savings by rehabilitating fewer pier caps and reducing the associated construction work and traffic disruption. The developed program, STM-CAP, can also be used when load rating concrete pier caps.

A comprehensive and practical performance measure, called Ohio Bridge Condition Index (OBCI), has been developed in this project. OBCI is a cost-based index that ranges from zero to one and represents the performance of bridges at element-, component-, bridge-, and network-levels. The index effectively uses ODOT's bridge inventory and inspection databases. Effects of serviceability and safety features of bridges are objectively incorporated in this index through a broad set of direct and indirect consequences of various bridge conditions. Based on this novel index and implementing a mixed-integer linear programing technique, a systematic optimal budget allocation algorithm is developed that identifies the optimal Maintenance, Repair, and Replacement (MR & R) work plans for National Highway System (NHS) bridges of ODOT's districts for available budgets. Application of the proposed index to numerous Ohio bridges show that OBCI not only reflects the impacts of structural deficiencies, but also the adverse consequences imposed on users due to repair actions. It is also demonstrated that OBCI can effectively identify bridges with safety concerns and estimate bridge repair costs for various target performances. Furthermore, through the application of the optimization algorithm for the 484 NHS bridges in District 3, it is shown that the algorithm systematically assigns higher priority to work plans that reduce safety risks of bridges, and to bridges with high traffic demand and long detour length to enhance their serviceability.

Recent innovations in the oil and gas industry have increased horizontal drilling and hydraulic fracturing activity in Ohio. As of July 2015, 1559 wells were planned or drilled in Ohio and 935 were producing. During its lifetime, each well site can generate up to 3000 additional truck loads. There is also increased truck activity to haul waste water away to injection well sites and to construct compressor stations and pipelines. These activities have resulted in a significant increase to the normal truck traffic volume experienced on the local road and bridge system. Ohio Senate Bill 315 requires oil or gas well operators enter into a Road User Maintenance Agreement (RUMA), or demonstrate a good-faith effort to do so prior to obtaining a drilling permit. By entering into a RUMA the company assumes a contractual obligation for maintaining or improving roads and bridges to mitigate the damage due to the excessive loads. A RUMA template was cooperatively developed by the Ohio Department of Transportation (ODOT), Ohio Department of Natural Resources (ODNR), oil and gas industry representatives, the County Engineer's Association of Ohio (CEAO), and other local transportation officials. As a home rule state, local agencies may modify the template for specific situations, resulting in many variations of the RUMA. Local agencies have also executed RUMAs with other industries such as coal, timber, wind energy, etc. In some instances, RUMAs may have been used in situations where their use is not necessarily appropriate, which has caused confusion among the local agencies and the industry. Although there has been a significant amount of study of the topic, this information is neither widely disseminated nor easily accessible to local officials. This information was collected from agencies in Ohio and elsewhere to find current and proposed practices via a literature search, a survey of counties and townships in Ohio, and interviews of select county engineers and township trustees. These practices are compared and the best presented in a matrix of best practices as well as guidelines and recommendations for local officials in Ohio.

Presentation giving an overview of agency operations, achievements and finances of the Kansas Department of Transportation.

The workshop held on March 28 at the MDOT Aeronautics Auditorium in Lansing, Michigan, was organized with the goal of providing an overview of readily available and proven NDE technologies and the process of integrating these technologies into the bridge management program. The presentations focused on the NDE technologies that have been successfully evaluated under laboratory and field conditions. Further, the capabilities and limitations of each technology were discussed with respect to the intended applications. Based on the information received during the workshop and the expertise of the authors, a two-tier inspection process and a NDE implementation program is described.

The proposed research will develop the application of Raman Spectroscopy as a nondestructive evaluation tool for the condition assessment of carbon fiber composites. Composite materials are increasingly being used in engineered structures and components, ranging from highway bridges to airframes and pressure vessels. These materials have a high strength to mass ratio, making them idealmaterials for inclusion in space vehicles, hydrogen cars and aircraft. There exists a critical need to develop nondestructive evaluation technologies that can be used to assess the condition of these materials in-situ, such that components and systems can be managed anrepaired during their service lives. To date, NDE technologies developed for the inspection of composite materials have focused on mechanical damage scenarios, such as impact and fatigue. There is growing concern that environmental degradation of these materials leads to reduced strength during their service lives, and presently there are no NDE technologies capable of characterizing the degradation of composite materials in-situ. The proposed research will investigate if Raman spectroscopy can be used for the condition assessment of composite materials during their service lives. Raman spectroscopy is a laser technique that is sensitive to molecular interactions in ordered materials such as graphite and carbon fibers. For carbon materials, the technique has been shown tobe sensitive to applied elastic stresses and structural order on a molecular level. Traditionally a laboratory technique, new instrumentation implementing fiber-optic probes has extended the potential for this technology beyond the laboratory. The potential exist for implementation as a hand-held device for the inspection of engineering components and structures, including bridges and hydrogen vehicles.

Much of Utah's population dwells in a seismically active region, and many of the bridges connecting transportation lifelines predate the rigorous seismic design standards that have been developed in the past 10-20 years. Other states in the west have instituted seismic retrofit programs in response to damage to transportation networks in past California earthquakes. In a parallel report, seismic retrofit guidelines were developed for Utah based on the Seismic Retrofitting Manual for Highway Structures published by FHWA. In this report, representative case study bridges are evaluated in detail using the guidelines. The case study evaluations include the following for each bridge: (1) selection and presentation of analysis method, (2) development of numerical model in LARSA 4D and/or additional programs as needed, (3) evaluation of the seismic response of the unretrofitted bridge, (4) design of a possible retrofit scheme. The bridges evaluated include a four-span simply supported prestressed concrete girder bridge, a four-span continuous concrete T-beam, and an eight-span curved steel girder bridge with in-span pin and hanger joints. A variety of different evaluation methods are presented including linear response spectrum analysis for demand assessment, capacity spectrum method and pushover analysis for capacity assessment, and nonlinear response history analysis. A variety of retrofit techniques are presented including column jacketing, cable restrainers, selectively closing pin and hanger joints, and seismic isolation. The varied examples and techniques presented in this report are meant to be representative of assessment and applicable retrofit approaches for many of the bridges in the state inventory that may be seismically deficient.

Bridge Health Index (BHI) is a bridge performance measure based on the condition of the bridge elements. It is computed as the ratio of remaining value of the bridge structure to the initial value of the structure. Since it is expressed as a percentage value, the BHI could provide an intuitive measure for bridge engineers, and legislators. The BHI could be converted to another measure such as color (red, yellow and green) that public understands better. The Pontis user group was surveyed to determine the current use of the BHI and other measures for bridge management decision making. This study focused on understanding the sensitivity of the BHI to small and large changes in the element failure costs and the element condition, the two input data sets for computing the BHI. For these sensitivity analyses, 221 bridges were selected from Wisconsin's inventory. The study looked at bridges with simple and continuous span prestressed concrete girders. The findings can guide state agencies and practitioners with a sense of how BHI responds to changing bridge condition as well as element failure costs. The element failure costs were acquired from a previous study by a consultant to the FHWA and the element level inspection data were from the Wisconsin Department of Transportation (WisDOT). The analysis considered the impact of Smart Flags used to identify local problems that are not reflected in the element condition states. Because they may indicate critical defects in the bridges, they should be reflected for BHI. To investigate the impact of Smart Flags, computation rules suggested by the Kansas DOT were applied to the selected bridges in Wisconsin.

The main purpose of this project was to assess the effectiveness of fiberglass wrappings in reducing the corrosion degradation rate of concrete bridge columns. To evaluate the effectiveness of the technique, the research team used both nondestructive and destructive test methods. The results of the study show that the wrappings, while protecting the columns from further ingress of chloride ions, do not help deter corrosion activity when it is already present. Recommendations for the future use of fiber wraps, complemented with other remediation techniques and maintenance practices, are provided.

The main purpose of this project is to assess the effectiveness of the fiberglass wrapping in reducing the corrosion degradation rate of the columns. To evaluate the effectiveness of the technique, the research team will use both non-destructive and destructive test methods. The results of the study will provide show that the wrapping while protecting the columns from further ingress of chloride ions, it does not help deter the corrosion activity when already present. Recommendation for future use fiber wraps complemented with other remediation techniques and maintenance practices are provided.

A collection of maps showing which bridges in Oklahoma are in grave need of repair due to age, structural deficiency, functional obsolescence, or inability to bear modern loads, with photographs of example bridges.

Timber material repair and replacement cost for timber bridges is a considerable expense to highway agencies in Iowa, especially to county road departments. To address these needs, the objectives of this investigation was to study the field effectiveness of various treatment alternatives used on Iowa roadway projects and to determine if the current specifications and testing are adequate for providing proper wood preservation. To satisfy the research needs, the project scope involved a literature review, identification of metrics, questionnaire survey of Iowa counties, on site inspections, and a review of current specifications and testing procedures. Based on the preservative information obtained, the following general conclusions were made: Copper naphthenate is recommended as the plant-applied preservative treatment for timber bridges. Best Management Practices should be followed to ensure quality treatment of timber materials. Bridge maintenance programs need to be developed and implemented. The Iowa Department of Transportation specifications for preservative treatment are the regulating specification for bridges constructed with state or federal funding in Iowa and are also recommended for all other bridges.

The main objective of this research is to non-destructively field test and evaluate ten (10) damaged/deteriorated, low-rated bridges in order to determine load carrying capacity. All test bridges were selected from the Ohio state inventory in conjunction with input from the ODOT Office of Structural Engineering. A detailed field test plan was developed for each test bridge and included modal testing, truckload testing, and calibrated FE modeling in order to derive accurate, objective load ratings. A secondary objective was to further streamline the field testing and assessment procedures. Specifically, the actual time for a 32-channel modal impact test and a 24-channel truckload test of a typical 3-span, 2 lane, 250 foot steel-stringer bridge was reduced to less than one workday for each test. This included test setup and teardown. The benefits of this research to ODOT have been the development of techniques, equipment packages, and a personnel team with the expertise necessary to implement rapid, rigorous, quantitative assessments of critical structures around the state. In addition to these procedures and expertise, deliverables included detailed reports of findings for each of the bridges in the test set.