What is this fatigue or fatigue strength ?
Fatigue is basically a synonym to exhaustion. But how can metal get exhausted or tired? When some sort of stress is repeated on some point of any given material, that point gets more and more weakened, only natural. And if the recurrence be really high, beyond a certain stage that material might breakdown even at a lesser single pressure than that is was normally supposed to absorb. That is ‘Fatigue’; as long as a material’s physical performance is concerned.
Likewise, ‘Fatigue Strength’ in relation to a particular material is the level of the cyclic stress which that material can tolerate. Generally it give an impression about that material’s long-term capacity to bear loads. A multi-storey building naturally has to face various loads and stresses years after year, which all leave a cumulative affect like a fatigue. As major and serious example moreover, an earthquake creates an extra-ordinary type of massive shake of your building. Shakes come as multi-directional waves and from all the sides of the structure in such a case, and this is called ‘Cyclic Loading’. Fatigue strength of a rod is tested in a laboratory just by creating such cyclic loading up to a real high number on the recurrence scale. And so, that suggest us about the rod’s capacity to bear such real huge loads.
Why is this fatigue test a must before your construction starts?
When there has been some crack, however small, due to fatigue; a rod can collapse even at a much lower stress that is capacity. The structures that use cement casting – such as bridges, flyovers, multi-storey houses and those erected near seashores – are more vulnerable to cyclic loads. And hence, when a structure of any of these types is going to be built, a fatigue test is for each rod to be used is just as essential as yield strength, tensile strength, elongation, bend and re-bend test.
As already covered above, the severity of an earthquake’s shakes and stresses is much higher than and different from that of any other type of load. And you also know, Bangladesh is one of the countries that are very prone to earthquakes. Various studies particularly suggest that Bangladesh is at a real high risk of heavy ones near future. Then why would you risk your home and future, by using a rod that is not fatigue tested?
BUET Fatigue Test Report of KSRM
To be certain and clear about a rod’s fatigue strength, you have to see not only how much cyclic loads it can take but also what the level of the applied load was. Take an example for the calculation. You are given two choices. One rod could bear 50 lakhs cyclic loads of 250 mega pascals, and the other one survived 50 lakhs cyclic loads of 350 mega pascals. Which one will you choose ? Of course the second one, since that could take same number of even heavier loads. This is why we have put an equal ephasis, while testing the fatigue strength of our rod, on the level of the cyclic loads side by side with their number.
A Super-satisfactory success of KSRM in Fatigue Test
In the BUET’s Fatigue Test, KSRM 500W has been able to bear 55 lakhs a plus cyclic loads of 369 megapascals, much higher than any other rod of Bangladesh ever could. So, simply choose KSRM 500W for your construction, without any worries. Keep safe and in peace, year after year after year.