Name: concrete fatigue under repeated loads
Uploaded: 2024-11-07T14:48:31.000Z
Duration: 1 min 22 s
Channel: JoVE

Dans le béton, la fatigue peut conduire à deux formes distinctes de défaillance. La première se produit sous une charge constante ou qui augmente progressivement ; C’est ce qu’on appelle la fatigue statique ou la rupture par fluage.
La deuxième forme de défaillance se produit sous des charges cycliques ou répétées, appelée fatigue cyclique.
La résistance à la compression est généralement mesurée dans un court laps de temps de 2 à 4 minutes. À mesure que le taux de charge diminue ou que la durée de l’essai augmente, la résistance mesurée descend en dessous de celle observée dans les essais standard.
À l'inverse, si la charge est appliquée rapidement ou presque instantanément, la résistance résultante est plus élevée, mais la déformation du matériau à la rupture, ou capacité de déformation, est réduite.
À de faibles taux de charge, la fatigue statique dans le béton se produit lorsque la contrainte dépasse environ 70 à 80 % de la résistance à court terme. Ce niveau marque le début de la formation rapide de microfissures, conduisant à une défaillance.
Le béton devient plus résistant en vieillissant et sa capacité à supporter des charges répétées, ou résistance à la fatigue, augmente proportionnellement. Cela signifie que le béton se rompt sous l’effet de la fatigue à des niveaux de contrainte proportionnels à la résistance finale, quel que soit l’âge.

résistance à la fatigue du béton

Fatigue Strength of Concrete

Dans le contexte de la science et ingénierie des matériaux, la fatigue désigne l'affaiblissement ou la défaillance d'un matériau causé par des charges appliquées de manière répétée, même si ces charges sont inférieures à la limite de résistance du matériau. La résistance à la fatigue du béton est une propriété essentielle qui influence sa durabilité et sa longévité. Le béton peut se rompre de deux manières en raison de la fatigue. La fatigue statique ou la rupture par fluage se produit sous une charge constante ou qui augmente lentement. L'autre mode de défaillance est dû à des charges cycliques ou répétées, appelé fatigue.


 Il est intéressant de noter que la résistance à la compression du béton, généralement mesurée sur une courte période de quelques minutes, varie en fonction de la vitesse à laquelle la charge est appliquée et de la durée de l’essai. Par exemple, une vitesse de chargement plus lente ou une durée d’essai plus longue entraîne une résistance mesurée plus faible. Dans le même temps, l’application rapide de la charge améliore la résistance mais réduit la capacité de déformation du matériau. La fatigue statique survient à de faibles taux de chargement lorsque la contrainte dépasse environ 70 à 80 % de la résistance à court terme, ce qui déclenche la formation rapide de microfissures et conduit à la rupture. À mesure que le béton vieillit, sa résistance et sa résistance à la fatigue augmentent en parallèle, ce qui indique que la rupture par fatigue se produit à un pourcentage constant de sa résistance maximale, quel que soit le nombre de cycles.

Résistance à la fatigue du béton

Dans le béton, la fatigue peut conduire à deux formes distinctes de défaillance. La première se produit sous une charge constante ou qui augmente progressivement ; C’est ce qu’on appelle ...

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Civil Engineering

Génie civil

Unit 1

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Strength of Concrete

Résistance du béton

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

concrete fatigue under repeated loads

Concrete fatigue describes how concrete can weaken or fail when loads are applied again and again, even when each load is below the material’s strength limit. This property matters because it affects the durability and service life of concrete structures. In materials science and engineering, fatigue is a key reason concrete may not last as long as expected under real use.

Concrete can fail in two main ways through fatigue. Static fatigue, also called creep rupture, happens under a constant load or a load that rises slowly. The other type comes from cyclical or repeated loading, which is simply called fatigue.

The measured compressive strength of concrete depends on how fast the load is applied and how long the test lasts. A slower loading rate or a longer test time gives a lower strength value. A rapid load can increase the measured strength, but it also reduces the strain capacity of the material.

Static fatigue usually begins when stress is above about 70 to 80 percent of the short-term strength. At this level, microcracks form quickly and can lead to failure. As concrete ages, both its strength and its fatigue strength increase together. This shows that fatigue failure tends to occur at a consistent percentage of the maximum strength, no matter how many loading cycles are involved.

Concrete Fatigue Under Repeated Loads

tensile strength considerations of concrete

tensile-strength-considerations-of-concrete

How Cracks Limit Concrete Strength

Concrete tensile strength is limited by tiny cracks inside the material. The cement paste itself can be much stronger in theory than it is in practice. In real concrete, the measured strength can be up to a thousand times lower than the theoretical value. These small cracks help explain that gap. When a load is applied, stress rises at the crack tips. This idea is described by Griffith's theory of brittle fracture. In brittle materials, cracks can grow quickly once the stress at their tips...

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behavior-of-concrete-under-compressive-load

Concrete Failure Patterns Under Compression

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Concrete Porosity and Durability

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microcracking in concrete

How Concrete Cracks Before Failure

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Concrete Strength and Water Balance

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aggregate cement ratio

How Mix Ratio Changes Concrete Strength

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Concrete Transition Zone and Its Porosity

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Concrete Strength Testing: Tension vs. Compression

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fatigue strength of concrete

Concrete fatigue describes how concrete can weaken or fail when loads are applied again and again, even when each load is below the material’s strength limit. This property matters because it affects the durability and service life of concrete structures. In materials science and engineering, fatigue is a key reason concrete may not last as long as expected under real use. Concrete can fail in two main ways through fatigue. Static fatigue, also called creep rupture, happens under a constant...

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Concrete Wear Tests and Surface Durability

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non-destructive tests for concrete strength

non-destructive-tests-for-concrete-strength

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key terms and concepts

Learn how concrete can fail under constant or repeated loads, why loading rate changes measured strength, and how aging affects fatigue strength.

Concrete Fatigue Under Repeated Loads | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Concrete Fatigue Under Repeated Loads

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