Stress Reversal in Steel Joist
Stress Reversal in Steel Joist
(OP)
I am trying to determine what exactly the stress reversal is in a steel joist. When I use Vulcraft's shear diagram assistant program on their website, it gives me the stress reversal as a %. I want to be able to calculate that percentage on my own but can't find anywhere that tells me exactly how to do that.
Any help you can give me would be much appreciated!
Any help you can give me would be much appreciated!






RE: Stress Reversal in Steel Joist
Magnitude of reversed shear at location / Magnitude of original shear at location * 100.
I haven't tinkered with Vulcraft's app though so you'll want to confirm that.
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.
RE: Stress Reversal in Steel Joist
If the joist has only uniform load on it, the SJI specs require that the webs to be designed for 1/4 of the max. end shear. This comes from the stress reversal in the webs that would occur due to a partial uniform load (from one end to the centerline of the joist).
You should easily be able do this by hand to check the program.
RE: Stress Reversal in Steel Joist
KootK, I looked into what you were saying but I can't get my hand calc'd number to match that of Vulcraft's % from their in web app. :/
RE: Stress Reversal in Steel Joist
Perhaps, another engineer in your office can help you with your hand calc. Breaking it down to different load conditions may help [dead load, live load, wind load (each direction)] you determine which combinations produce the maximum in Vulcraft's program.
RE: Stress Reversal in Steel Joist
RE: Stress Reversal in Steel Joist
RE: Stress Reversal in Steel Joist
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.
RE: Stress Reversal in Steel Joist
unless of course, you are in possession of the original joists designs in which such a stress reversal percentage is provided as original joist design criteria.
As I understand it, your (OP) statement at 14:08 today is almost correct except that the midspan actual shear is divided by theoretical end reaction of a joist selected for which its uniform load shear diagram completely encompasses your actual shear diagram; and it extends for a distance from midspan to the place of actual 0 shear.
Unwieldy for me anyways, and I cannot see any value in reinforcement scenarios, unless again you are in possession of original design criteria.
Agree with the rest of the above comments.
Normal web reinforcements for a 14K1 would be 2 angles per web, each welded to the vertical leg of the top and bottom chord. Design new double angle reinforcement to take total force requirement at that web.
RE: Stress Reversal in Steel Joist
RE: Stress Reversal in Steel Joist
RE: Stress Reversal in Steel Joist