Dear friends

Please provide me suggesion regarding maximum allaowable stresses due to sustatined loading (i.e 0.66 Sy or 0.25 S ult whichever is less) so i am little confuse about 0.25 of S ult. from which calculation it comes.Please help.

Hi Kaps,

All the values are resulted from monotonic tensile tests, and the aim of agreement on a percentage of whole amount is making sure to stay in linear elastic zone. For more information you may have a look at the mechanical behaviuor of engineering material texts.