Surreal illustration of a historic bridge with glowing stress lines.

Hercílio Luz Bridge: Can Modern Assessments Save Historic Structures from Fatigue?

Beau Callahan in Tech & Innovation December 2025 • 4 min read.

"A meticulous fatigue analysis of Brazil's iconic Hercílio Luz Bridge reveals critical insights for preserving aging infrastructure worldwide."

Bridges, essential arteries of our transportation networks, face a relentless enemy: fatigue. This insidious process, born from the constant barrage of traffic and environmental stressors, can weaken a bridge's structure, leading to performance degradation and, in severe cases, catastrophic failure. The Hercílio Luz Bridge in Brazil, a historic eyebar suspension bridge, stands as a testament to this challenge. Built in 1926, it has endured decades of service, and now faces severe fatigue damage.

Recognizing the urgent need to safeguard this iconic landmark, engineers have undertaken a comprehensive fatigue assessment. This evaluation employs sophisticated techniques and modern standards to understand the bridge's current condition and guide its rehabilitation. The assessment leverages Eurocode fatigue load models to scrutinize the riveted and welded connections, pinpointing areas of critical stress and potential failure.

But why focus so intently on fatigue assessment? For aging bridges like the Hercílio Luz, these evaluations are vital. They provide invaluable insights into the structure's remaining lifespan, helping authorities prioritize maintenance, allocate resources effectively, and implement targeted strengthening measures. This proactive approach not only enhances public safety but also preserves these historic structures for future generations.

Decoding Fatigue Assessment: How It Works

Surreal illustration of a historic bridge with glowing stress lines.

Fatigue assessment is a multi-faceted process designed to evaluate the endurance of a structure under repeated loading. For the Hercílio Luz Bridge, this involved:

Load Modeling: Engineers used Eurocode fatigue load models (FLMs) to simulate the stress the bridge experiences from traffic. These models consider the weight and frequency of vehicles, providing a realistic representation of daily use.

Stress Range Analysis: This step calculates the range of stress fluctuations in critical connections, particularly riveted and welded joints. High stress ranges are indicative of potential fatigue hotspots.
Cumulative Damage Calculation: Using the stress range data, engineers estimate the cumulative damage to the connections over time. This helps predict how long the bridge can safely operate under current conditions.
Code Comparison: The original bridge design followed 1926 AASHTO standards. The new assessment compares Eurocode results with those obtained using current AASHTO procedures to highlight differences and ensure a comprehensive evaluation.

The analysis specifically targeted floor-beam-to-truss and stringer-to-floor-beam connections, especially those near the eyebar chain transition. These areas are prone to stress concentration, making them vulnerable to fatigue damage.

Looking Ahead: Protecting Our Bridges

The Hercílio Luz Bridge study offers crucial lessons for maintaining aging infrastructure. By employing modern assessment techniques and comparing them with original design standards, engineers can identify vulnerabilities and implement targeted strengthening measures. This proactive approach not only extends the lifespan of these vital structures but also ensures the safety of the public for years to come. Continuous monitoring, advanced materials, and innovative repair techniques are key to preserving our bridges and safeguarding our transportation networks.

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This article is based on research published under:

DOI-LINK: 10.1061/(asce)cf.1943-5509.0001236, Alternate LINK

Title: Fatigue Assessment Of Critical Connections In A Historic Eyebar Suspension Bridge

Subject: Safety, Risk, Reliability and Quality

Journal: Journal of Performance of Constructed Facilities

Publisher: American Society of Civil Engineers (ASCE)

Authors: Zhongxiang Liu, Matthew H. Hebdon, José A. F. O. Correia, Hermes Carvalho, Paula M. L. Vilela, Abilio M. P. De Jesus, Rui A. B. Calçada

Published: 2019-02-01

Everything You Need To Know

What is fatigue and why is it a concern for bridges like the Hercílio Luz Bridge?

Fatigue is a process where a structure weakens due to repeated stress from traffic and environmental factors. For bridges like the Hercílio Luz Bridge, which was built in 1926, decades of service have caused significant fatigue damage, threatening its structural integrity and safety. Fatigue assessment helps understand the extent of this damage and guides necessary rehabilitation efforts. Without these assessments, issues will go unchecked and could potentially lead to catastrophic failure.

How does fatigue assessment work on a bridge like the Hercílio Luz Bridge?

Fatigue assessment involves several steps. First, load modeling is performed using Eurocode fatigue load models (FLMs) to simulate traffic stress. Then, stress range analysis calculates stress fluctuations in critical connections like riveted and welded joints. Cumulative damage calculation estimates damage over time to predict the bridge's safe operational life. Finally, results are compared with both current AASHTO procedures and the original 1926 AASHTO standards to ensure a comprehensive evaluation. This is important for understanding the condition of bridges and where they need to be strengthed.

What are Eurocode fatigue load models and how were they used in the Hercílio Luz Bridge assessment?

Eurocode fatigue load models (FLMs) are used to simulate the stress that a bridge experiences from traffic by considering the weight and frequency of vehicles. In the Hercílio Luz Bridge assessment, these models were used to provide a realistic representation of daily use to scrutinize the riveted and welded connections, pinpointing areas of critical stress and potential failure, such as floor-beam-to-truss and stringer-to-floor-beam connections, especially near the eyebar chain transition, because these areas are prone to stress concentration.

Why is it important to compare modern assessment results with the original design standards of the Hercílio Luz Bridge?

Comparing modern assessment results, such as those from Eurocode, with the original 1926 AASHTO standards helps highlight differences and ensure a comprehensive evaluation. This comparison is important because the original design might not account for current traffic loads and modern safety factors. Identifying these discrepancies allows engineers to understand how the bridge's performance has changed over time and implement targeted strengthening measures, enhancing safety and extending the structure's lifespan. In some cases, new AASHTO procedures and guidelines will need to be made.

What are the broader implications of the Hercílio Luz Bridge fatigue study for maintaining other aging bridges and infrastructure?

The Hercílio Luz Bridge study provides key strategies for maintaining aging infrastructure globally. By using modern assessment techniques and comparing them with original design standards, engineers can identify vulnerabilities and implement targeted strengthening measures. Continuous monitoring, using advanced materials, and applying innovative repair techniques are crucial for preserving bridges and safeguarding transportation networks. This proactive approach extends the lifespan of vital structures and ensures public safety, offering a blueprint for managing similar challenges worldwide.