Gang Chen SS practice exam question 106

Structural Layout Vignette and Multiple Choice

Gang Chen SS practice exam question 106

Postby pig » Tue Jan 30, 2018 4:41 pm

hi all,

gang chen's practice exam has this question - pls see attachment.
the answer is C (column c takes most load), but i don't understand his explanation on this. his explanation is that column c is the shortest so it needs to be the"stiffest".
but would it not be column B because it takes on the load of half of the existing building and half of the new addition?
anyone who can help, please kindly explain.

thank you!
pig
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Re: Gang Chen SS practice exam question 106

Postby lali » Tue Jan 30, 2018 7:34 pm

The key word is LATERAL FORCE
In vertical force, yes B received more load. On lateral, C is the weak point of the structure (a point of irregularity). Lateral forces get stronger as you get higher in the building.
That is the only explanation I can find.

Laura
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Re: Gang Chen SS practice exam question 106

Postby pig » Tue Jan 30, 2018 8:17 pm

hi laura,
that is so brilliant!!
thank you so much!!
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Re: Gang Chen SS practice exam question 106

Postby lali » Thu Feb 22, 2018 5:29 pm

I just found a better answer to the "short column" statement. Reading FEMA buildings at Risk, they mention the "short column" phenomenon. Basically when you have a lateral force, it gets atracted to the memebers that have more rigidity. A short column has more rigidity than a taller one, and that is why the short columns shown in the graphic will receive more load than the rest. You can read FEMA BUILDINGS AT RISK chapter 4.
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