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RE: AISC Appd. 'B' - Qs
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- Subject: RE: AISC Appd. 'B' - Qs
- From: "Effland, Greg" <geeffland(--nospam--at)butlermfg.com>
- Date: Wed, 1 Aug 2001 10:04:55 -0500
Rich, Your on the right track... 1) If when calculating Qa you get an effective width (be) greater than or equal to the actual width (b) then you are correct using Qa = 1.0. 2) For a tube column there are no unstiffened compression elements therfore Qs = 1.0. Q= Qs * Qa Make sure you use Q in the Axial allowable as per Eqn. A-B5-11 and to limit allowable bending values to <= 0.6*Fy*Qs (insignificant in this particular case since Qs=1) and modify equations H1-2 and A-F7-13 as per Appendix B5.2.d HTH, Greg Effland, P.E. KC MO -----Original Message----- From: richard lewis [mailto:rlewistx(--nospam--at)juno.com] Sent: Tuesday, July 31, 2001 4:51 PM To: seaint(--nospam--at)seaint.org Subject: AISC Appd. 'B' - Qs I have a question regarding using AISC Appendix 'B'. I have a HSS 10x10x1/4 column with axial load and bending. The b/t ratio of 39.9 exceeds the noncompact requirement which makes me check Appd. 'B'. A tube is a stiffened compression element which uses Section B5.2.b to calculate the effective width. As I understand it the 'f' value is the stress in the flange of the tube from bending and axial load. This is used to calculate the effective width of the tube. In my case the 'f' value is 19.7 ksi. This makes the effective width 'be' = 9.51 inches. The real width of the tube flange is 9.30 inches (39.9*the thickness of 0.233 inches of the flange) so I can use the real section properties of the tube because these are less than the 'be' properties. 'Qa' will then equal 1.0. Is this correct? How do I calculate 'Qs' for the tube column. Appd. 'B' Section B5.2.a is for unstiffened elements. What is the equation for a stiffened element of a tube? Rich ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. * * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to: * * http://www.seaint.org/sealist1.asp * * Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you * send to the list is public domain and may be re-posted * without your permission. Make sure you visit our web * site at: http://www.seaint.org * * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to: * * http://www.seaint.org/sealist1.asp * * Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you * send to the list is public domain and may be re-posted * without your permission. Make sure you visit our web * site at: http://www.seaint.org
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