Floor Joist Analysis

[FoamGuy]

I have a simply supported Douglas Fir floor joist that has a simply supported, 16-foot span. I am getting too much deflection in the center of this span. I have enough room to add an 8-foot long steel flitch plate in the center of the span. Could someone help me in how to calculate the stresses/deflections in this composite beam?

 

[Ron]

This link was hijacked from a previous post in "Structural" by "slide rule era"

http://www.destefanoassociates.com/tech/flitch.pdf

 

[swearingen]

Slide rule era's link gets him part of the way there. Foamguy, you'll have to calculate your stresses the hard way since your stiffness changes along your beam. Take a shot at it and if you can't get it (and I have time today), I'll give you some pointers.


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[FoamGuy]

Thanks swearingen. I've been away from beam analysis for about twenty years. Analyzing a simply supported, standard beam is simple enough, but one that has a different cross section and higher stiffness for the middle eight feet is beyond my abilities. Any help you can provide would be much appreciated.

 

[swearingen]

It turned out that it's pretty involved, so I banged it out last night - I checked it and it was wrong, so I've got it in the hands of one of our young engineers to find the little negative sign I missed somewhere...


If you "heard" it on the internet, it's guilty until proven innocent. - DCS

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[FoamGuy]

Thanks again, swearingen. Let me know if the young guys figure it out. I was thinking that it could be solved by analyzing the wood and the metal beams separately and then combining the results by superposition, but it became pretty tricky.

 

[swearingen]

Got it!


If you "heard" it on the internet, it's guilty until proven innocent. - DCS

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