This research focused on developing an inspection protocol for post-tensioning (PT) ducts employing flexible filler materials for corrosion protection in bridge applications. Historically, cementitious grouts (CG) have been used to provide corrosion protection and bonding in PT systems. In contrast, flexible filler systems use wax or grease to maintain a physical barrier for corrosion protection but result in unbonded tendons. An initial literature survey focused on bonded systems with CG for corrosion protection, which led to the identification of three nondestructive evaluation (NDE) methods that show promise for flexible-filler systems: ultrasound coda-wave interferometry, thermoelasticity, and radiography for anchorage cap imaging. Key priorities for the experimental work, which were identified in consultation with Florida Department of Transportation (FDOT) project managers, include NDE methods for identifying micro-cracking and assessing stress levels in concrete and non-invasive NDE methods for identifying corrosion in tendons and anchorages. Proof-of-concept testing for thermoelasticity and ultrasound interferometry was conducted in Embry-Riddle Aeronautical University (ERAU) laboratory facilities using small-scale specimens. Thermoelasticity was not effective for assessing the stress level in concrete and was removed from consideration. Preliminary investigations into ultrasound interferometry did demonstrate a capability for evaluating the change in stress level and presence of non-visible cracking. Proof-of-concept testing for radiography was completed using external contractors in October 2021 using large-scale specimens from other testing programs at the FDOT Structures Lab in Tallahassee. This testing yielded positive results for identifying wedge-grip dislocations at anchorages and tendon location in ducts. Large-scale testing was completed at the FDOT Structures Lab in Tallahassee during Summer 2023. Ultrasound interferometry was evaluated during post-tensioning and 4-point bending. Ultrasound interferometry was capable of identifying cracking during 4-point bending well before barely-visible cracking was observed.
This Data Spotlight presents information about the Port of Baltimore in response to the Francis Scott Key Bridge collapse on the morning of March 26, 2024. Data includes Port of Baltimore international inbound and outbound vessel calls by draft and vessel type, 2021, and a map of the Port of Baltimore's marine terminals. The Francis Scott Key Bridge carried 12.5 million vehicles in 2023, averaging more than 34,000 vehicles a day over the year. This is 15 percent of the total traffic for all 3 harbor crossings, and the diverted traffic would add 18 percent to the combined volumes for the Fort McHenry and Harbor Tunnels.
The accumulation of sediments at culverts is a chronic operational issue, frequently occurring at multi-barrel culverts located in erosion-prone watersheds. Sediment deposits can develop rapidly, impairing the culvert’s capacity to convey design flows and potentially leading to damage to both transportation infrastructure (e.g., road and culvert overtopping) and upstream areas (e.g., flooding). Current culvert design protocols focus primarily on flood flow conveyance, with less attention given to assessing the potential for sedimentation due to the limited understanding of the complex erosion and transport processes leading to culvert sedimentation. Consequently, costly culvert cleaning is often required to maintain operational functionality. The overarching goal of this experimental study, funded by the Iowa, Mississippi, Missouri, New Mexico, and Utah Departments of Transportation (DOT), is to develop mitigation solutions for reducing or eliminating sediment accumulation at three-barrel culverts. The study builds on the experience garnered through pioneering research initiated by the Iowa DOT to substantially advance the understanding of complex flow and sediment transport through culverts located in various hydrological and geomorphological conditions. The proposed mitigation solutions are based on the Self-Cleaning-Culvert (SCC) concept, which relies on the stream’s hydraulic power to pass sediment carried by the stream through culverts. The laboratory study entails 180 stand-alone tests conducted in two flume arrangements: Iowa-Mississippi-Missouri (IMM) and New Mexico-Utah (NMU). The tested SCC designs demonstrated satisfactory sediment conveyance efficiency for the IMM culverts, with more than half of the designs increasing sediment conveyance capacity by 50 to 72%. However, the addition of the SCC at the NMU culvert entrance displayed reduced conveyance (less than 25%) due to changes in geometry that further hampered the structure’s capability to handle the much heavier sediment load carried by typical NMU flash floods compared to the extreme precipitation events occurring in the IMM landscape.
Each year, the South Dakota Department of Transportation (SDDOT) builds a number of box culverts through its highway construction program. In the past, cast-in-place box culverts were used exclusively, but use of precast box culverts is becoming a viable option. With cast-in-place box culverts, beveled inlet edges and 30° flared wingwalls are used at the inlet because that is usually the most efficient inlet shape. When precast box culverts are used, the inlet ends available from the South Dakota precast industry are mitered end with 0° flared wingwalls which have a standard four inch (regardless of barrel size) beveled edge along the bottom of the top edge of the inlet opening and along the top inside edge of the wingwalls. Current design methods, such as computer program HY8, do not provide for this mitered inlet option because, to our knowledge, model testing has not been conducted for this configuration. The Turner-Fairbank Highway Research Center agreed to determine inlet loss coefficients for certain inlet types used by SDDOT. The initial models were built and hydraulics testing performed as a graduate research fellowship project. Unfortunately, the models were not properly constructed and did not conform to the plans. As a result, the inlet loss coefficients determined by testing were not valid. After the research panel pointed this out, the research center agreed to accurately reconstruct the models and perform the tests again. The Research Center contracted with GKY & Associates, Inc., who took over the study and completed it in four months. During retesting, Richard Phillips, SDDOT Hydraulics Engineer, inspected a representative number of the new models and found them to accurately represent the box culvert inlets submitted for testing. The results indicate that the use of 30° flared wing walls, as on cast-in-place inlets, is slightly more hydraulically efficient than straight wing walls with beveled edges, as on precast culverts.
The majority of bridges in Texas are constructed with girders as simple spans. A simple-span deck requires expansion joints, which are sources of maintenance and durability issues. To avoid this, continuous decks, known as “poor boy joints” in Texas Department of Transportation (TxDOT) bridges, are an attractive option. These details are commonly known as link slabs. Despite a four-decade history of use, a comprehensive evaluation of the performance of this detailing has not been conducted. In this study, finite element modeling and full-scale experimental tests were used to conduct an evaluation of existing TxDOT continuous deck details and propose design recommendations. Both bonded and debonded link slabs were considered. While both types of link slabs have been investigated in the literature, the investigation presented in this report offers several unique aspects. Consideration of the use of partial-depth precast panels is crucial because the detailing of panels in the link slab region can have a significant influence on cracking in the link slab. Another area impacting the formation of damage is the presence of a crack former on the top and bottom of the deck, a detail commonly used in practice but not investigated via analysis or experimental testing. The experimental tests were full-scale tests and utilized two girder lines, a unique characteristic that allows for documentation of differences in damage in overhangs and between girder lines. Based on the findings of the experimental test program, this report provides design recommendations for limits on which bridges current TxDOT link slab details should be used, as well as recommendations for designs that utilize debonded link slabs, continuous panels, and a haunch gap at the end of the girder.
This project develops a novel gaze-directed Unmanned Aerial Vehicles-Unmanned Ground Vehicle (UAV-UGV) coordination framework for on-site quality inspection of precast bridge construction. UAV will provide global coverage for inspectors to quickly identify the components and construction activities for inspection while UGV will navigate to specific locations for close inspection following human guidance. A new gaze-directed human-machine interface, where inspectors can express their guidance via natural gaze movements, to reduce worker mental load. The framework is intended to transform the practice of onsite quality inspection for precast infrastructure construction by establishing intuitive multi-robot-human teaming for efficient inspection. Such a system can be extended to provide guidance during bridge installation, thus improving construction quality and durability with reduced rework. The researched framework can also be extended for lifecycle inspection, including offsite component inspection and condition monitoring of existing infrastructure, and eventually improve the durability and extend the life of precast transportation infrastructure.
Camber in precast and prestressed concrete is currently designed using best practices in structural engineering and subject to climate and loading uncertainties. Applying new technology of adaptive structures, large shape change in response to load, to precast concrete bridge girders would pioneer a new innovative field of research and design. This work building, analyzing, and validating an adaptive precast girder system that will use expanding anchors to camber the compression face of the girder to counteract imposed loads. By providing on-demand camber, sizing of the precast member for deflection criteria can be reduced. Through this form of topology optimization, reduction in concrete volume will increase the sustainability of the structural system. Laboratory experiments have lead to fundamental science and implementable technology. Adaptive precast girders can address long-term effects of creep and changing design loads over the lifetime of highway bridges.
Abstract of the final report is stated below for reference: Camber in precast and prestressed concrete is currently designed using best practices in structural engineering and subject to climate and loading uncertainties. Applying new technology of adaptive structures, large shape change in response to load, to precast concrete bridge girders would pioneer a new innovative field of research and design. This work building, analyzing, and validating an adaptive precast girder system that will use expanding anchors to camber the compression face of the girder to counteract imposed loads. By providing on-demand camber, sizing of the precast member for deflection criteria can be reduced. Through this form of topology optimization, reduction in concrete volume will increase the sustainability of the structural system. Laboratory experiments have lead to fundamental science and implementable technology. Adaptive precast girders can address long-term effects of creep and changing design loads over the lifetime of highway bridges.
Abstract of the final report is stated below for reference: This project develops a novel gaze-directed Unmanned Aerial Vehicles-Unmanned Ground Vehicle (UAV-UGV) coordination framework for on-site quality inspection of precast bridge construction. UAV will provide global coverage for inspectors to quickly identify the components and construction activities for inspection while UGV will navigate to specific locations for close inspection following human guidance. A new gaze-directed human-machine interface, where inspectors can express their guidance via natural gaze movements, to reduce worker mental load. The framework is intended to transform the practice of onsite quality inspection for precast infrastructure construction by establishing intuitive multi-robot-human teaming for efficient inspection. Such a system can be extended to provide guidance during bridge installation, thus improving construction quality and durability with reduced rework. The researched framework can also be extended for lifecycle inspection, including offsite component inspection and condition monitoring of existing infrastructure, and eventually improve the durability and extend the life of precast transportation infrastructure.
This document provides technical information on the hydraulic analysis and design of bridges. The goal is to provide information so that bridges can be designed as safely as possible while optimizing costs and limiting impacts to property and the environment. Many significant aspects of bridge hydraulic design are discussed. These include regulatory topics, specific approaches for bridge hydraulic modeling, hydraulic model selection, bridge design impacts on scour and stream instability, and sediment transport.
