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RE: Structural Engineering Rules of Thumb
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 Subject: RE: Structural Engineering Rules of Thumb
 From: "Rich Lewis" <seaint05(nospamat)lewisengineering.com>
 Date: Sun, 7 Feb 2010 21:55:06 0600
Several years ago, make that many years ago (red book), I worked
out the formulas in the AISC beam diagrams to calculate deflection based on
moment. I worked it out for moment to be in kft and length to be in
feet. These are easy formulas to remember. I copy them over every
time I get a new AISC book. Uniform load Delta=5wl^4/(384EI) For steel this is Delta=(M*L^2)/(161*I)
For any other material it is delta=(180*M*L^2)/(E*I) Point load in middle Delta=Pl^3/(48EI) For steel this is Delta=(M*L^2)/(201*I) For a center peak triangular load Delta=(W8l^3)/(60*E*I) For steel this is Delta=(M*L^@)/(168*I) And I did this for several more load cases. What is
interesting is the Uniform load produces the highest deflection. It has
the smallest denominator constant. So, if you want a quick conservative
deflection check, not matter what the actual loading is, the Delta=(M*L^2)/(161*I)
will give you the largest deflection possible. Reverse Delta and ‘I’ and you get quick equations to
calculate minimum ‘I’ required for a deflection ratio limit. I usually have my results from analysis in kft & ft so
these formulas are very handy. Rich From: G Vishwanath
[mailto:gvshwnth(nospamat)yahoo.com]

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 RE: Structural Engineering Rules of Thumb
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