This session examines the assessment and repair of segmental bridges and their components. Due to their design and unique components, assessments of segmental bridges require evaluations that are not typically performed in other bridges. This includes locating voids of grouted tendons, examination of post-tensioned tendon corrosion, and verification of as-built conditions. This session will include case studies that bring to light recent advances in the assessment and repair methods of segmental bridges.
Learning Objectives:
(1) Understand the unique design and construction aspects of segmental bridges;
(2) Discuss the key challenges with the inspection and assessment of segmental bridges;
(3) Discuss the reliability of different non-destructive testing (NDT&E) techniques in evaluating segmental bridge components;
(4) Discuss the reliability of instrumentation and monitoring methods in evaluating corrosion damage of the prestressing tendons in segmental bridges.
A Historic Overview of Precast Concrete Box Girder Bridge Research and Implementation in the United States
Presented By: John Myers
Affiliation: Missouri S & T
Description: This presentation will provide an overview of early work undertaken both experimentally and analytically on the development and implementation of precast concrete box girder bridges. This includes the first segmental precast prestressed concrete box girder bridge built in the United States, namely the John F. Kennedy Memorial Causeway, Corpus Christi, Texas, and how laboratory research led to its construction.
Insights into Segmental Bridge Maintenance: Critical Components, Distress Identification, and Repair Design
Presented By: Glenn Tindale
Affiliation: Corven Engineering, An H&H Company
Description: This presentation provides a concise overview of three key aspects that collectively offer a foundational understanding of the maintenance process specific to segmental bridges. The initial segment delves into the distinctive critical components inherent in segmental bridges. It offers insights into past rehabilitation projects where these components were compromised and explains how the inherent characteristics of segmental bridges facilitate the redistribution of forces, indicating signs of distress prior to failure. The second segment focuses on the identification of distress signals in a segmental bridge, encompassing the appearance of such signs, inspection methodologies, and the evaluation for these inspections. Finally, the third segment highlights the prerequisites for designing an effective repair strategy for segmental bridges. This includes considerations of qualifications, modeling requirements, and the unique field conditions that designers must account for in the process.
Condition Assessment of a Segmental Bridge During Construction
Presented By: Jorge Hernandez Carranza
Affiliation: Pivot Engineers
Description: During the construction of a segmental bridge, the Owner requested a condition assessment of the partially erected bridge superstructure. At the time, all precast segments needed for the bridge had been fabricated and approximately 60% of the segments had been erected.
The condition assessment included a suite of non-destructive testing techniques and exploratory openings. The investigation revealed several construction-related issues. This presentation examines the improper placement of the transverse PT tendons in the precast segments and cast-in-place closure segments. This issue was systemic and widespread. To reach this conclusion, Pivot collected more than 2 miles of scans using ground-penetrating radar (GPR). The presentation will also discuss the remediation measures used to alleviate the identified misplacement of the tendons.
VDOT’s Experience in the Evaluation and Monitoring of Tendons in Segmental Bridges
Presented By: Amir Behravan
Affiliation: Virginia Transportation Research Council
Description: The Varina-Enon Bridge is a cable-stayed segmental bridge carrying I-295 traffic over the James River. Lord Delaware and Eltham Bridges are post-tensioned, lightweight PCBT girders continuous over four spans, carry traffic on US 33 over the Mattaponi and Pamunkey Rivers. These three bridges all have been identified to have premature problems related to post-tensioned tendons. Consequently, significant voids, soft grout, and free water were found in several of the girders and external tendons, and concerns about potential strand corrosion arose. Several nondestructive test methods were employed to assess the condition of the tendons and grout. Also, instrumentation is in place to identify wire/strand breaks. Further evaluations and repair methods are being assessed in order to extend the service life of these important bridges. This presentation will cover the pros and cons of the test methods deployed.
Using Nondestructive Testing and Evaluation (NDT&E) for As-Built Verification and Condition Assessment of Segmental Bridges
Presented By: Marisol Tsui-Chang
Affiliation: BDI
Description: Nondestructive testing and evaluation (NDT&E) and structural health monitoring (SHM) have gained significant popularity since these can provide valuable information for bridge owners to make effective and data-driven decisions regarding bridge maintenance, rehabilitation, and overall asset management. This presentation will consist of two case studies on the use of NDT&E and SHM for as-built verification and condition assessment for several segmental bridges in the country. From an inspection and structural standpoint, segmental bridges can be complex structures and can be challenging for inspectors and engineers relying on visual and physical verification tools only. For example, inspecting and monitoring a structure with a post-tensioning (PT) system, incomplete as-built or structural plans, or difficult access conditions would render the need for more advanced tools that can collect information from the bridge over time.