几何尺寸与公差论坛------致力于产品几何量公差标准GD&T (GDT:ASME)|New GPS(ISO)研究/CAD设计/CAM加工/CMM测量

几何尺寸与公差论坛------致力于产品几何量公差标准GD&T (GDT:ASME)|New GPS(ISO)研究/CAD设计/CAM加工/CMM测量 (http://www.dimcax.com/hust/index.php)
-   产品功能分析 (http://www.dimcax.com/hust/forumdisplay.php?f=10)
-   -   beam loading help (http://www.dimcax.com/hust/showthread.php?t=21879)

huangyhg 2009-09-07 02:56 PM

beam loading help
 
beam loading help
i haven't done this in years so i am hoping someone will refresh my memory. i need to find the maximum weight that can be handled safely on structural tubing (ansi a500) class b - 2 x 2 x 16 ga wall. the weight will be uniformly distributed along a 48" span. the supports will be fixed at either end. i know this seems simple but i just want to make sure i am doing this correctly. thanks in advance
find a job or post a job opening
if its just strength you are looking for, do the following:
1) determine sx of your section.
2) determine allowable stress (fy) of steel. normally .66 fy therfore you have (0.66 x 50)=33 ksi.
3) determine allowable moment of your section.
mmax= fa (in psi) * sx (in in 3)/ 12
4) mmax= w* l * l/8
where l is your span (4'-0). this will give you in pounds per foot.
hope this helps.
geoff
double check that you have the right tubing spec- i didn't realize it went down to anything that small and light. also, check to make sure it qualifies as compact, or whatever the criteria is (ie, not too thin-walled relative to width).
possibly also check for crippling of the webs and shear issues at the ends. if this is a critical
a500 class b for a square tube: fy=46ksi, not 50 ksi.
the maximum moment for the fix-fix condition (which occurs at the ends) is =wl^2/12 (not wl^2/8).
i prefer lrfd method instead of asd, so i would take .9(fy)sx for the nominal moment allowed and compare it to factored max moment. then solve for sx. this only works if the section compact, and i think in your case, 48" is too long and the walls are too thin, therefore the section is probably non-compact.
no solve for sx, solve for w. whoops, i'm thinking design, not analysis.


所有的时间均为北京时间。 现在的时间是 05:16 AM.