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2 Beam Deflection Equation

  1. Mar 15, 2012 #1

    I would like to know how to find the deflection of simple 2 beam assemblies. In college, I remember only doing one beam problems. For example, a beam supported at both ends with a load in the center would follow the equation v_max= -(P*L^3)/(48*E*I).

    What if 2 identical beams supported at both ends are place on top of each other and perpendicular. Looks like a square cross at the top view and the load is applied in the center. Is there an max deflection equation for that?

    I'd assume the load could be cut in half and calculated with the one beam equation?
  2. jcsd
  3. Mar 15, 2012 #2


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    Gold Member

    As long as the two beams are exactly alike (same length, same end support conditions) and the intersection is exactly at the middle with effectively a ball support at that point (so that there is no moment transfer), then the deflection will be half that of a single beam. If any of these special conditions are not met, then the problem is more complex because you have load sharing between the two beams, and it becomes necessary to determine how much load is taken in each beam. This is a statically indeterminate problem.
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