Beam/ Column Behavior Due to Lateral Loads

[Mark1921]

I was watching a video about Introduction to Earthquake Engineering and got stuck in this frame. If my memory serves me right, the moment resulting from that beam displacement would be clockwise and not counter clockwise as shown in the screenshot. Can anybody shed light on this for me. Thanks.

 

[Whoopdedo_LSU]

1) What are you asking?
2) Earthquake or live lateral load diagram should not change depending on support at base.
3) If that's a completely rigid beam at the top, I would not consider it if determining loads at base supports (i.e. cantilever beam).


Note: I've found not to assume rigidity unless on short span lengths.

 

[KootK]

The moments coming into the ends of the column would definelt both be CCW per the sketch on the right.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Mark1921]

But isn't the moment coming from the joint to column CW? Therefore, the induced moment on column's ends would be CCW.
But If I follow the diagram I encircled in the picture and draw the figure vertically, the moments drawn in the picture are CW. Is it wrong?

 

[Mark1921]

That settles it, then. Thank you KootK. The video was from NPTEL lectures. The lecturer overlooked that part.

 

[KootK]

I see what you're getting at now. In the circled sketch, I would have drawn both the moments and shears reversed in typical free body diagram fashion. The author either made an error or, perhaps, intended to show the actions imposed by the columns on the beam and foundations for some reason. Hard to say without hearing the narrative that went with it.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.