DAM Yi

[SteelPE]

I am a little confused on exactly what Yi is in the Direct Analysis Method. Is Yi the total weight of the structure at level i, or is it the loads applied to the frame at level i?

 

[271828]

The load applied at Level i.

Try this to prove it to yourself.

Create a 2-3 story frame and assign some load at each level. Displace the frame to the right by H/500 at each story. Now compute the overturning moment about the base.

Now, use the same frame, except not pushed to the right by H/500. Add notional loads equal to 0.002*Yi at each level, where Yi = the vertical load at Level i. Now compute the overturning moment due to these notional loads and see that it's the same as the one computed per the previous paragraph.

 

[271828]

To be clearer, all load applied at level i, including leaner columns. Not just applied directly to frame members.

 

[SteelPE]

I am trying to check a computer program to make sure it is applying the correct loads during the DAM. I just want to make sure my interpretation of Yi is correct.

So the lateral load I apply to the frames are suppose to be 0.002*(the total load applied to level i).

 

[frv]

Note that Yi is the Factored load combination.