Lateral Loads on Podium Level

[DC_Engr]

Hi All, I am working on a 'podium' level design that has columns and walls landing on its slabs and beams from floor above. The entire podium is going to be topped with 4" concrete topping. The columns and walls transfer not just the usual gravity loads but seismic loads that are shown to act in both vertical and horizontal direction. If we assume the lateral (horizontal) loads, at the base of upper story columns & walls, are taken out in diaphragm and therefore beams & slabs only need to be sized for gravity loads plus vertically directed seismic loads; would that be correct assumption? Note that podium is not CIP, so members are typically connected at ends with simple roller or pin type connections. Let me know your thoughts, thanks.

 

[HTURKAK]

NO!!!!

Refer to two stage analysis procedure if the stiffness of the lower portion is at least 10 times
the stiffness of the upper portion or Vertical Combinations Different systems ..

https://www.structuremag.org/?p=10934

I cannot give you the formula for success, but I can give you the formula for failure..It is: Try to please everybody.

 

[KootK]

As I understand it, this is a delegated engineering assignment for you (based on your other thread in this sub-forum).

The topping probably can be assumed to resist the diaphragm shear. Where you might get into trouble is in the design of discrete members within the diaphragm that act as collectors. Drag struts, chords, etc. Frankly, you've got little hope of figuring that out without the EOR's help. Half the time, what is and is not a collector comes down to little more than whether or not the EOR said it was or was not a collector. You'll need their input.