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

In concrete, fatigue can lead to two distinct forms of failure. The first occurs under a consistent load or one that increases gradually; this is referred to as static fatigue or creep rupture.
The second form of failure happens under cyclical or repeated loads, called cyclic fatigue.
Compressive strength is typically measured in a short span of 2 to 4 minutes. As the loading rate decreases or the test duration increases, the measured strength dips below that observed in standard tests.
Conversely, if the load is applied rapidly or nearly instantaneously, the resulting strength is higher, yet the material&#39;s strain at failure, or strain capacity, is reduced.
At low loading rates, static fatigue in concrete happens when stress surpasses approximately 70 to 80 percent of the short-term strength. This level marks the beginning of swift microcrack formation, leading to failure.
Concrete becomes stronger as it ages, and its capacity to endure repeated loads, or fatigue strength, increases proportionally. This means concrete fails under fatigue at stress levels proportional to the ultimate strength, regardless of age.

vermoeidheid sterkte van beton

Fatigue Strength of Concrete

Vermoeidheid, in de context van materiaalkunde en -techniek, verwijst naar de verzwakking of het falen van een materiaal veroorzaakt door herhaaldelijk toegepaste belastingen, zelfs als deze belastingen onder de sterkte grens van het materiaal liggen. Vermoeidheid sterkte in beton is een kritische eigenschap die de duurzaamheid en levensduur ervan beïnvloedt. Beton kan op twee manieren falen door vermoeidheid. Statische vermoeidheid of kruip breuk treedt op bij een constante belasting of een belasting die langzaam toeneemt. De andere faalmodus is te wijten aan cyclische of herhaalde belastingen, bekend als vermoeidheid.

Interessant genoeg varieert de druksterkte van beton, die doorgaans in een korte tijdspanne van een paar minuten wordt gemeten, met de snelheid waarmee de belasting wordt toegepast en de duur van de test. Een lagere belasting snelheid of een langere testduur resulteert bijvoorbeeld in een lagere gemeten sterkte. Tegelijkertijd verbetert een snelle toepassing van belasting de sterkte, maar vermindert de rek capaciteit van het materiaal. Statische vermoeidheid ontstaat bij lage belasting snelheden wanneer de spanning ongeveer 70 tot 80 procent van de korte termijn sterkte overschrijdt, wat leidt tot snelle micro scheurvorming en falen. Naarmate beton ouder wordt, nemen de sterkte en vermoeiingssterkte gelijktijdig toe, wat aangeeft dat vermoeiing falen optreedt bij een consistent percentage van de maximale sterkte, ongeacht het aantal cycli.

Vermoeidheid sterkte van beton

In concrete, fatigue can lead to two distinct forms of failure. The first occurs under a consistent load or one that increases gradually; this is referred ...

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JoVE Core

Civil Engineering

Civiele techniek

Unit 1

Strength of Concrete

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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

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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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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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