Load Percentage

[Engineer22]

[No message]

 

[tenguy23]

Are these sketches of plan views or elevation views?

What are the loads/load-path? I'm having trouble visualizing your Free-Body-Diagram (if these are intending to be FBDs).

 

[bigirishman]

Looks like a case study of the Hyatt Regency Collapse.  Load on the nut doubles with the offset.

 

[TehMightyEngineer]

Looks like a case study of the Hyatt Regency Collapse.  Load on the nut doubles with the offset.

This. If it's a double channel for the box beam then it's definitely Hyatt Regency. That's a case study all structural engineers should be familiar with.

 

[Engineer22]

Thanks

 

[Engineer22]

Looks like a case study of the Hyatt Regency Collapse.  Load on the nut doubles with the offset.

Which scenario are you referring to (a or b?), and what is the percentage load on the nut?

 

[Engineer22]

Can anyone help me with this structural question? Thanks!

 

[bigirishman]

Sorry, didn't recheck the forum.

The original design had a single rod with each floor (and therefore each nut) supporting the weight of 1 floor.  By offsetting the rod connecting the lower floor, the upper floor now supports both the lower and upper floor weight.  So the nut in question (and the floorbeam) now has to support both floors, and was not resized for the additional forces.

 

[Engineer22]

Thanks!

 

[Engineer22]

Thanks!

 

[StructEngBrah]

 

[Engineer22]

Understood

 

[StructEngBrah]

I mean, it states it on the picture.   The difference is 100%, P vs. 2P.

"P" is the load on each platform.  The right picture, which is how the Hyatt Regency was built, ends up with the nut bearing on the steel section with a force of 2P.   The force from the bottom platform and top platform bear on the nut.  With the left picture, the nut only takes the load from the top platform and bears on the steel section with a force of P.   The design calculations for the Hyatt assumed the connection would be built like the left, but the right was actually built and end up failing. It's a small difference in connection scheme, but your design force on the nut is increased by 100% from the original scheme.

I highly recommend you google this.  This engineering failure is probably the most famous and is covered at length on multiple websites.  I am probably not doing a great job explaining it, but you can find a bunch of resources online.

 

[Engineer22]

OK