Bridge Instrumentation and the Development of Non-destructive and Destructive Techniques Used to Estimate Residual Tendon Stress in Prestressed Girders

Bridge Instrumentation and the Development of Non-destructive and Destructive Techniques Used to Estimate Residual Tendon Stress in Prestressed Girders
Author: Brian M. Kukay
Publisher:
Total Pages:
Release: 2008
Genre: Electronic dissertations
ISBN:

This research embodied a three-prong approach for directly determining the residual prestress force of prestressed concrete bridge girders. For bridges that have yet to be constructed, outfitting girders with instrumentation is a highly effective means of determining residual prestress force in prestressed concrete bridge girders. This constitutes the first prong. Still, many bridges are constructed without such instrumentation. For these bridges, a destructive technique can be used to directly determine the residual prestress in a prestressed concrete bridge girder. This implies that the girder(s) being tested have already been taken out of service. This constitutes the second prong. For bridges that are anticipated to remain in service that are lacking embedded instrumentation, the development of a non-destructive technique used to estimate the remaining force in the tendons of prestressed bridge girders is extremely important. This constitutes the third prong used to directly determine residual prestress force. The flexural capacity was also determined from field tests and compared to analytical estimates. By design, the code estimates are meant to be conservative. Alternatively, the residual prestress force for in-service members can be determined directly through the non-destructive technique presented in this research. As such, bridge service capacities can be determined directly and do not need to be conservatively estimated.

Experimental and Analytical Evaluation of Residual Capacity of Corrosion-Damaged Prestressed Concrete Bridge Girders

Experimental and Analytical Evaluation of Residual Capacity of Corrosion-Damaged Prestressed Concrete Bridge Girders
Author: Ali Alfailakawi
Publisher:
Total Pages: 64
Release: 2020
Genre: Prestressed concrete beams--Testing
ISBN:

The durability of infrastructure components, such as prestressed concrete bridge beams, can be significantly affected by long-term deterioration associated with corrosion. Corrosion is a major concern for bridges in Virginia, due to the frequent use of deicing salts during the winter, as well as the number of structures in marine environments. The residual capacity of corrosion damaged prestressed I-beams and box beams needs to be accurately estimated to determine if damaged bridges need to be posted, and to help with making informed decisions related to repair, rehabilitation and replacement of damaged bridges. This report presents the results of testing of six corrosion-damaged prestressed beams removed from existing bridges during their demolition. Three beams were Type II AASHTO I-beams extracted from the Lesner Bridge in Virginia Beach, and three were 48 in wide by 27 in deep box beams extracted from the Aden Road Bridge near Quantico, Virginia. Prior to testing, the beams were visually inspected and two types of non-destructive evaluations were performed to identify corrosion activity: resistivity measurements and half-cell potential measurements. The beams were then tested in the lab to determine their flexural strength. Following testing, samples of strand were removed and tested to determine their tensile properties. Cores were taken from the Aden Road beams and from both the beams and decks of the Lesner Bridge beams to determine compressive strength. Powdered concrete samples were removed to perform chloride concentration tests. The tested strengths of the beams were compared to calculated strengths using two methods for damage estimation and two different calculation approaches. The methods for damage estimation relied exclusively on visual inspections; one was the set of methods recommended by Naito et al. (2010), while the second was a modified method developed in this study from the current tests. The two calculation approaches were a strain compatibility method and the AASHTO LRFD method. Overall, the results yielded reasonable estimates of residual strength, except for one of the box beams that was discovered to have considerable water within the hollow cells. The final recommendations are that bridge inspectors develop detailed damage maps of corrosion-damaged beams, and that load raters use the Naito et al. method to get a conservative estimate of damage for both box beams and I-beams. Either method for calculating strength is valid, however the AASHTO LRFD method is simpler.

Prestress Losses in Pretensioned High-strength Concrete Bridge Girders

Prestress Losses in Pretensioned High-strength Concrete Bridge Girders
Author: Maher K. Tadros
Publisher: Transportation Research Board
Total Pages: 73
Release: 2003
Genre: Technology & Engineering
ISBN: 030908766X

"The HCM includes three printed volumes (Volumes 1-3) that can be purchased from the Transportation Research Board in print and electronic formats. Volume 4 is a free online resource that supports the rest of the manual. It includes: Supplemental chapters 25-38, providing additional details of the methodologies described in the Volume 1-3 chapters, example problems, and other resources; A technical reference library providing access to a significant portion of the research supporting HCM methods; Two applications guides demonstrating how the HCM can be applied to planning-level analysis and a variety of traffic operations applications; Interpretations, updates, and errata for the HCM (as they are developed);A discussion forum allowing HCM users to ask questions and collaborate on HCM-related matters; and Notifications of chapter updates, active discussions, and more via an optional e-mail notification feature."--Publisher.

Acoustic Emission Sensing for Crack Monitoring in Prefabricated and Prestressed Reinforced Concrete Bridge Girders

Acoustic Emission Sensing for Crack Monitoring in Prefabricated and Prestressed Reinforced Concrete Bridge Girders
Author: Robert Lee Worley (II)
Publisher:
Total Pages: 266
Release: 2019
Genre: Acoustic emission testing
ISBN:

Prefabricated and pre-stressed reinforced concrete beams and girders are integral components of many highway structures, including those built by rapid construction techniques. Concerns exist regarding the development of cracks during curing, form removal, detensioning, transport, installation, and operation. Non-destructive, Acoustic Emission (AE) sensing techniques have the potential for detecting and locating cracking in prefabricated, pre-stressed concrete girders used as Prefabricated Bridge Elements and Systems (PBES) used in rapid construction practices as part of a Quality Assurance/Quality Control (QA/QC) program. AE sensing records transient elastic waves produced by the release of stored elastic energy resulting in plastic deformations (i.e., crack nucleation and growth) with an array of point sensors. The AE instrument system is relatively portable which can allow for it to be an option for both off-site fabrication QA/QC as well as on-site field QA/QC. This thesis presents a multi-stage research initiative on acoustic emission monitoring of prefabricated and pre-stressed reinforced concrete beams used in highway bridge construction during detensioning, craned removal from formwork and transport to bridge sites, along with supporting laboratory tests and numerical analysis. The specific objectives of this research were to: 1. Identify suitable instruments to monitor pre-stressed and/or post-tensioned concrete girders for cracking activity; 2. Design and develop a reusable instrumentation package; 3. Measure performance and condition of concrete girders during fabrication and transport; and 4. Identify test protocols and possible accept/fix/reject criteria for structural elements based on information from monitoring system. Presented are results from laboratory, full-scale girder fabrication, and transport monitoring, along with overall conclusions and recommendations for future research.

Non-destructive Evaluation Method for Determination of Internal Grout Conditions Inside Bridge Post-tensioning Ducts Using Rolling Stress Waves for Continuous Scanning

Non-destructive Evaluation Method for Determination of Internal Grout Conditions Inside Bridge Post-tensioning Ducts Using Rolling Stress Waves for Continuous Scanning
Author: Tinkey Yajai
Publisher:
Total Pages: 33
Release: 2006
Genre: Bridges
ISBN:

This Innovations Deserving Exploratory Analysis project developed a nondestructive method based on impact-echo and ultrasonic reflection techniques with continuous scanning features for determining the grout condition inside post-tensioned bridge ducts. Initial efforts were focused on evaluating and establishing the accuracy/reliability of the impact echo scanning test. The impact echo scanner hardware was modified by incorporating a rolling transducer into the prototype to overcome the problem of variable thickness. The scanner software was also improved to provide three-dimensional display of impact echo results. Data on a mock-up slab fabricated with defects of different types and sizes and collected using the modified instrument were analyzed. Visualization from three-dimensional surface plots helped interpret the data. The presence of a tendon duct and grouting discontinuities appeared to cause an increase in the apparent slab thickness. Two U-shaped precast bridge girders with four ducts on each wall were procured from the Colorado Department of Transportation for full-scale tests. Impact echo tests using a rolling scanner at different times after the grouting process were performed on the walls of the girders.