How does Etabs calculate maximum drift for semi-rigid diaphragm?

[NTCONLINE]

Hi,
Each floor consists of many FE nodes, each node has its own deflection value.
So how does Etabs calculate the maximum story drift automatically?
does it choose the node that has the maximum deflection at each floor?

I believe for rigid diaphragm, the calculation is simply based on the master node as all nodes have the same deflection. I am just unsure for the semi-rigid case.

Cheers
NTC

 

[Trenno]

I believe, could be wrong, ETABS looks at the deflections between vertically similar nodes (ie sharing the same X&Y coords), then performs the drift calculation using the storey heights.

That's how I do manually anyway. Select a joint somewhere on the corner or facade, extract displacement values for wind loads, extract the storey heights and do my own drift calculations within Excel.