Model shows inaccurately large deflection?
Model shows inaccurately large deflection?
(OP)
Hi,
I've modeled a 1 story building according to the plans and given steel shapes,
It appears there is one problem area which has high deflection.
I've attached a screen shot showing the worst deflection, about 3.2"
After changing the beam section many times we've reduced it further but my boss and I believe something is wrong with the analysis thus resulting in too large of a deflection.
We applied a 175 psf dead load and 200 psf live load.
What I did was draw a floor around the entire perimeter of the plan, and then applied the load to that.
We tried both individual dead/live loads, and just one load of 375 psf.
We're designing in ASD so we do not want any load combinations to be applied, and I do not know if any are being applied or not?
My boss has calculated the deflection due to the reactions on that beam using the A-beam app and the numbers do not match ETABS.
Any advice suggestions?
I will upload the etabs file but unfortunatly I did this project in the evaluation version.
Thanks,
I've modeled a 1 story building according to the plans and given steel shapes,
It appears there is one problem area which has high deflection.
I've attached a screen shot showing the worst deflection, about 3.2"
After changing the beam section many times we've reduced it further but my boss and I believe something is wrong with the analysis thus resulting in too large of a deflection.
We applied a 175 psf dead load and 200 psf live load.
What I did was draw a floor around the entire perimeter of the plan, and then applied the load to that.
We tried both individual dead/live loads, and just one load of 375 psf.
We're designing in ASD so we do not want any load combinations to be applied, and I do not know if any are being applied or not?
My boss has calculated the deflection due to the reactions on that beam using the A-beam app and the numbers do not match ETABS.
Any advice suggestions?
I will upload the etabs file but unfortunatly I did this project in the evaluation version.
Thanks,





RE: Model shows inaccurately large deflection?
I've attached the .zip folder with the ETABS files
RE: Model shows inaccurately large deflection?
RE: Model shows inaccurately large deflection?
I now understand you're saying the 3.2" is net displacement from 0 that that particular joint has moved.
How would I use ETABS to give me just the displacement of one particular beam due to the loading, NOT including the displacement of the other beam's it is anchored to?
As in , if I'm using the ETABS deflection #'s to design this building and to check L/360 maximum deflection under total load of the beam...
I take 29' x 12 / 360 = 0.967"
Where do I find the number corresponding to the maximum deflection under total load of this one particular beam (in ETABS) to compare to my 0.967" to see if I meet the design requirement?
Thanks,
RE: Model shows inaccurately large deflection?
anyone have an answer for how to find actual deflection of a beam , not displacement of a node?
Thanks.
RE: Model shows inaccurately large deflection?
Now if you right click on the beam while showing the moment or shear there is also a deflection also shown from memory, you can select "relative to ends" or something like that. I don't have etabs in front of me at the moment to verify exact steps, but it's hidden away in one of those dialog boxes.