Retrofit Existing Beam - Residual Stress 1

[LH1120]

Afternoon,

I am currently working on strengthening an existing steel beam which we are rerouting a load path into causing it to be overstressed. We will be unable to "unload" the beam prior to retrofitting the reinforcement. Therefore due to residual stresses in the existing beam, the stresses within the composite beam will not be evenly distributed. This seems to me to require a nonlinear analysis. Does anyone have any experience preforming this type of analysis or any handy references which may pertain?

Thanks!

 

[dhengr]

LH1120:
Let’s see if I’ve got your scenario right. You can’t get in around the existing beam to shore it up before you add the new loading, but you can get in there to work, add some reinforcement, after the fact. How does that work? Sounds kinda fishy, or a poorly thought out retrofit scheme. You are going to apply the new load, thus overstressing the existing beam. At this point, what is the beam stress, its deflection, is still stable, etc? Then you are going to come in and add some sort of reinforcement, to the overstressed, over deflected beam, so that it doesn’t become even morely overstresseder? Those aren’t really residual stresses, they are just the normal stresses in the existing beam due to the combined loading.

As seems all too common these days, here on E-Tips, you haven’t given the least hint of load magnitudes, there direction and location of application; the existing beam size, span length, support conditions, etc. etc. Bldg. plans, elevations, various sections needed to visualize the situation. That’s most of the basic engineering info. needed to start to really understand the problem, and comment on it. Remember, we can’t see it from here, we don’t have the benefit of plans in front of us, so we are kinda in the dark, except ‘it’s a beam.’ There are likely a number of ways to do what you are trying to do, but you need to start by looking at the bigger picture, not just ‘it’s a beam.’

 

[WARose]

It's hard to say without knowing what the old stresses are.....and what the new stresses will be.

 

[kipfoot]

I've done it by adding the 'before' stresses (existing dead load) with the 'new' stresses (new dead and live). Check out the AISC presentation Designing of Strengthening for Existing Steel Members at about 50:00 of the webinar:

https://www.youtube.com/watch?v=c2f5et7z-PA

 

[dik]

Do you have to concern yourself with residual stresses?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik