Sessions & Events

Evaluation and Load Testing of Concrete Bridges More Than 75 Years Old, Part 1 of 2

Tuesday, April 1, 2025  8:30 AM - 10:30 AM, Civic Ballroom North

Historically, bridges for highway or rail service have been designed for a 50-year service life, but various societal and economic factors have led to many structures remaining in service well past that time. There can be challenges to evaluating the remaining life and load capacity of reinforced concrete bridges that are more than 75 years old. Accurate prediction of bridge capacity relative to sustained or changing load demands can be critical to evaluate aging bridges that may or may not show visible signs of distress. Often the lack of reliable information regarding design details and material characteristics makes analytical rating of such older bridges difficult. The main learning outcome is to become aware of how in-situ evaluation and load testing can inform maintenance, planning and asset management, and retrofit/replacement decisions for older structures.

Learning Objectives:
(1) Identify the challenges associated with evaluating the remaining service life of reinforced concrete slab bridges that are more than 75 years old;
(2) Identify the challenges associated with evaluating the remaining load capacity of reinforced concrete slab bridges that are more than 75 years old;
(3) Identify how a lack of reliable information regarding design details and material characteristics makes analytical rating of older bridges difficult;
(4) Identify how in-situ evaluation and load testing can inform maintenance, planning and asset management, and retrofit/replacement decisions for old structures.

This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.

Evaluation of RC Slab Bridges with Vintage Detailing – Case of the Nieuwklap Bridge

Presented By: Eva Lantsoght
Affiliation: Universidad San Francisco de Quito
Description: A large number of reinforced concrete solid slab bridges in the Netherlands require assessment, as these bridges were designed using the codes and live load models from the past. Most of these bridges were designed in the 1960s-1970s, but a smaller subset has been designed and constructed before, during, or shortly after the Second World War. In this presentation, we will explore the assessment of the Nieuwklap Bridge, located in the province of Groningen. The Nieuwklap Bridge was scheduled for demolition and replacement and considered a candidate for a collapse test. To identify if this bridge could generate research insights regarding shear failure, an extensive assessment of the bridge was carried out. In this presentation, we will focus on the assessment using different Levels of Approximation for existing concrete slab bridges, and particularly those with vintage detailing, such as the Nieuwklap bridge. The details of this bridge include bent-up bars as well as special anchorage hooks that may provide shear resistance, and vintage pendulum-style support conditions. The assessment shows that more precise estimates of the load effect can be obtained at a higher Level of Approximation, resulting in a lower Unity Check (ratio of factored demand to factored capacity) and that the influence of the vintage details is uncertain until test results become available. In conclusion, this presentation shows how assessment at different Levels of Approximation is currently carried out in the Netherlands, and how vintage details are considered or may provide additional capacity, as illustrated by the case of the Nieuwklap Bridge.

Evaluation and Modeling of 75-Year-Old Slab-Span Bridges

Presented By: Bruno Massicotte
Affiliation: Polytechnique Montreal
Description: This is an abstract that the author will submit. So far, they have not responded in a timely manner and sent an abstract after volunteering a talk for this session. They'll have to send one as soon as possible.

Evaluation of the US 175 Bushy Creek Slab Bridge in Kaufman, TX

Presented By: Nur Yazdani
Affiliation: University of Texas at Arlington
Description: Bridge widening is a common solution to increase the traffic capacity of existing bridges, allowing them to meet the evolving demands without full replacement. Evaluation of such widened bridges is essential to verify structural integrity, ensure load-sharing between the original and new sections, and address potential issues related to differential material aging. This presentation will discuss the detailed evaluation of the US 175 Big Brushy Creek slab bridge in Kaufman, TX, employing non-destructive evaluation (NDE) and load testing. Ground Penetrating Radar (GPR) and Impact Echo (IE) technologies were used to obtain a profile of the deck conditions including delamination and concrete cover. Diagnostic load testing incorporated strain gage data to quantify live-load response and compute load rating factor.

Evaluation of a 100-Year-Old Reinforced Concrete Slab Bridge

Presented By: Andrzej Nowak
Affiliation: Auburn University
Description: This is an abstract that the author will submit. So far, they have not responded in a timely manner and sent an abstract after volunteering a talk for this session. They'll have to send one as soon as possible.

Evaluation of Load Posted Reinforced Concrete Slab and Girder Bridges Built in Missouri: The Strategies Undertaken for Upgrade & Monitoring Through Load Testing

Presented By: John Myers
Affiliation: Missouri S & T
Description: This presentation examines five bridges older than 75 years in age that were load posted in Missouri due to changes in load classifications and or age. These five bridges were then strengthened with composite systems with the objective to bring the bridges to today’s load rating criteria and allow for the load posting removal. This presentation will examine the strengthening approach and present the load testing results both prior to strengthening, immediately after strengthening and then reoccurring in situ load testing for several years after strengthening to examine any softening in the system as well as load distribution of the girder bridges with and without the strengthen system. The umbrella project, entitled Preservation of Missouri Infrastructure: Validation of FRP Composite Technology Through Field Testing was designed to push forward composite strengthening schemes for use on real structures.