Multiple Diaphragms in ETABS 1

[Kasian15]

I have a building with expansion joints in which 4 sections of the building act seperatly. Each section has its own diaphragm. In ETABS when the wind loads are placed on the building, is each section/diaphragm loaded from all sides independently or is the wind placed on the overall building. By placing the load on the overall building it would take into account the EJ and not place wind on the sections adjacent to each other, where in reality there is no wind.

 

[slickdeals]

Each diaphragm is loaded independently. Unfortunately, there is no good way to go about assigning diaphragm loads.

What I have done in the past is to use null area objects on the facade and apply a pressure coefficient (0.8, 0.5 and 0.7) as applicable to (windward, leeward and sidewall).

The ETABS manual explains how to do it.

 

[PicoStruc]

Don't know if it help.. but i use this procedure to apply accidental torsion on different diaphragm on same story !

1) use Quake/User Load as pattern
2) For the "Modify Loads" window, you can assign load to each diaphragm individually for each story.

 

[asixth]

Shouldn't they be 4 separate building models to get meaningful results regards to natural frequency and building modes? That's if the 4 structures are independent.

If it was independent diaphragms sharing the same podium I would model as one.