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Overturning Moment & Stabilizing Moment
Posted:
Sat Oct 03, 2015 8:11 pmby lilly9
Can someone walk me through the steps of figuring out question #28 in the NCARB Exam Guide:
http://www.ncarb.org/ARE/~/media/Files/ ... _Guide.pdf (see link for diagram)
What is the factor of safety against overturning for the concrete shear wall shown if resisted only by gravity forces? Assume the weight of concrete equals 150 lb/ft3, and the dead load equals 240 kips. Ignore the weight of the soil over the footing.
Answer: 4.2
Thank you!
Re: Overturning Moment & Stabilizing Moment
Posted:
Sun Oct 04, 2015 12:37 pmby mono
Have you tried looking at Mikes notes for the NCARB exam guide?
Re: Overturning Moment & Stabilizing Moment
Posted:
Sun Oct 04, 2015 1:01 pmby lilly9
Thanks for the help -- I get it now!
Re: Overturning Moment & Stabilizing Moment
Posted:
Wed Jun 07, 2017 1:53 pmby ballet3gal
I have this same question. How do you do it? Or where are Mike's notes as referenced above?
Re: Overturning Moment & Stabilizing Moment
Posted:
Fri Jun 23, 2017 3:06 pmby Coach
ballet3gal wrote:I have this same question. How do you do it? Or where are Mike's notes as referenced above?
viewtopic.php?f=8&t=1171
Re: Overturning Moment & Stabilizing Moment
Posted:
Fri Jun 23, 2017 3:26 pmby Coach
ballet3gal wrote:I have this same question. How do you do it? Or where are Mike's notes as referenced above?
Find total dead load moment about the lower right corner. Find the overturning moment. Divide DL moment by overturning moment.
[((((16*40*1.5)+(20*6*2))*150)/1000)+240]*10 = 4200'k
24*42 = 1008'k
4200/1008 = 4.17
Re: Overturning Moment & Stabilizing Moment
Posted:
Fri Jan 12, 2018 2:38 pmby Femmemirage
How do you find the #10 in this equation?
[((((16*40*1.5)+(20*6*2))*150)/1000)+240]*10 = 4200'k
24*42 = 1008'k
4200/1008 = 4.17
Thanks!
Re: Overturning Moment & Stabilizing Moment
Posted:
Fri Jan 12, 2018 2:54 pmby Coach
Femmemirage wrote:How do you find the #10 in this equation?
[((((16*40*1.5)+(20*6*2))*150)/1000)+240]*10 = 4200'k
24*42 = 1008'k
4200/1008 = 4.17
Thanks!
It's the moment arm for the dead load.