# Lateral Deflection of Frames



## Casey (Aug 2, 2008)

Is there a good chance we will be asked to calculate the deflection of a frame, or of a structure in the exam? I can see that happening on one of the seismic questions and quite possibly on a column question where we would be required to use the second-order by amplified first-order analysis method...

If so, does anyone know of any quick techniques? Virtual work is probably the best way to go if the structure isn't too complicated. In one of my Kaplan books

"Structural Engineering - PE License Review Problems and Solutions" 6th Edition, pg 21 [i am sure the older editions have the same question]

Williams solves for the deflection of a portal frame using virtual work, but he doesn't actually show you how he goes about solving the integral. He just says "the integral is most readily evaluated by applying the volume integration technique."

Now, I assume that this "volume integration technique" is some trick that saves you some time instead of actually determining the moment equations and then solving for the integral.

Does anyone have any idea what this technique is? I've been scouring google, but with no success...

I am just wanting to avoid having to plug through a time-consuming integral.


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## Vinsanity (Aug 2, 2008)

Casey said:


> Is there a good chance we will be asked to calculate the deflection of a frame, or of a structure in the exam? I can see that happening on one of the seismic questions and quite possibly on a column question where we would be required to use the second-order by amplified first-order analysis method...
> If so, does anyone know of any quick techniques? Virtual work is probably the best way to go if the structure isn't too complicated. In one of my Kaplan books
> 
> "Structural Engineering - PE License Review Problems and Solutions" 6th Edition, pg 21 [i am sure the older editions have the same question]
> ...


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## Vinsanity (Aug 2, 2008)

I was wondering what loads are applied on your frame if it is pure lateral load on joints of frame, you can use Portal method or Cantilever method, this only involves static eqns. and that would be the quickiest. or assume points of inflection on beams and columns for gravity loads and also apply static eqns.

hope this helps.


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## kevo_55 (Aug 3, 2008)

Casey said:


> Is there a good chance we will be asked to calculate the deflection of a frame, or of a structure in the exam? I can see that happening on one of the seismic questions and quite possibly on a column question where we would be required to use the second-order by amplified first-order analysis method...
> If so, does anyone know of any quick techniques? Virtual work is probably the best way to go if the structure isn't too complicated. In one of my Kaplan books
> 
> "Structural Engineering - PE License Review Problems and Solutions" 6th Edition, pg 21 [i am sure the older editions have the same question]
> ...


Casey,

I have no idea what technique this is but I doubt that you would have to go into such detail in order to calculate it.

If you are to calculate a frame you would be asked to simply do it. Remember, half of the SEII exam is judgement. When asked to calculate the frame for lateral loads why not do what Vinsanity said and state that you are doing it via the portal method as your first statement in the problem?

If you were asked to calculate the total lateral displacement of a frame I would do it as a frame stiffness method as shown in the very next example problem.

Good luck and keep studying man.


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