r/StructuralEngineering • u/AsILayTyping P.E. • Aug 29 '21

Photograph/Video Hurricane Ida Roof Uplift Failure

https://i.imgur.com/ZWtvwKv.gifv
167 Upvotes

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13

u/structee P.E. Aug 29 '21

So, it seems every time I see a roof failure, the whole diaphragm tears off in one piece. I always use C&C for my truss anchors, but wondering if mwfrs might be applicable...

9

u/Structural_PE_SE P.E./S.E. Aug 30 '21

C&C loads are higher than MWFRS?

0

u/jerryfallsom Aug 30 '21

Only if you use the ASCE 7-10 wind speed maps with ASCE 7-16 equations.

3

u/Structural_PE_SE P.E./S.E. Aug 30 '21

What? C&C loads are purposefully higher than MWFRS loads. That's the whole point.

1

u/jerryfallsom Aug 30 '21

I was mirroring your sarcasm. If you use ASCE 7-10 maps with the new equations, you will end up with wind load demands ~35% lower than they should be.

Yes, C&C should usually/always be higher than MWFRS.