In what circumstances we can use the " Recommended loads", "Design resistance" or "Characteristic resistance"?
Many thanks.
Hi Daniel,
Thank you for your question.
Characteristic resistance is defined as resistance derived as the 5% fractile of the mean ultimate resistance, determined from tests or by empirical calculation depending on mode of failure. This is based upon a 90% probability (confidence level) that 95% of anchors will exceed the characteristic resistance.
Design resistance is the characteristic resistance divided by material partial safety factor (typically 1.5 for concrete failure modes). When using this value compare with factored loads or design loads. This approach can be used when a Global FOS of 3 is not needed in the design, typically for temporary works and civil works.
Also if you use a load factor of 2 in your design, then the Hong Kong Building Department requirement of FOS = 3 (Load factor X Material factor) can be fulfilled using design resistance compared with factored loads or design loads
Recommended load is the characteristic resistance divided by a global factor of 3. When using this value compare with un-factored loads. This fulfills the HK Building Department FOS = 3 requirement.
Please let us know if you have any further questions.
Cheers,
Tania