How does Staad calculate SQX and SQY exactly?

Question

Hello. 
 I&acute;m designing some footings in Staad and when I was checking for shear stresses (SQX and SQY) I noticed that the output value was pretty high for my dimensions and loads, so I tried to check how Staad obtains said values and I found in Chapter 1.6.1 of the Staad technical reference that SQX and SQY are obtained as Force/Unit lenght/thickness. So I guess my question is: What exactly is this "Unit length" is it 1 cm, 1 m maybe the plate element dimension? Because for some reason I&acute;m not getting coherent results between the Staad results and what I got from hand calculation.

Sye · Answer

The units used to report the SQX and SQY would indicate that. For example if the SQX is reported as 35 psi, then the shear force over 1 inch of length along element local X, per 1 inch thickness of the element is 35 pounds.

Sye · Answer

SQX/SQY are the shear stresses. So if you want to find out the shear force, you would have to multiply these by the respective shear area which would be equal to critical perimeter x effective depth.

How does Staad calculate SQX and SQY exactly?

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