Mean value of Second moment of area
Mean value of Second moment of area
(OP)
Hi
I would like to know if someone knows hove to calculate the mean value of Second moment of area (I) for serial connected steel beams.
I my case I have one case with 4 beams, and one with 11, with different I and different length placed on top of each other and would like to calculate I for the entire beam.
If some one can help me I would be really glad
I would like to know if someone knows hove to calculate the mean value of Second moment of area (I) for serial connected steel beams.
I my case I have one case with 4 beams, and one with 11, with different I and different length placed on top of each other and would like to calculate I for the entire beam.
If some one can help me I would be really glad





RE: Mean value of Second moment of area
you can take each beam as a lumped area at their centroids with its MoI about its centroid,
then the neutral axis of the assembled beams is ...
ybar = sum(Ay)/sum(A)
and MoI = sum(I)+sum(Ay^2)-sum(A)*ybar^2
good luck
RE: Mean value of Second moment of area
IPAXIS = ICM + Ah2 (parallel axis)
where:
IPAXIS = SMOA about the parallel axis
ICM = SMOA of the section about its centre of mass
A = area
h = distance to the centre of mass
The sum of the above for the entire section will give you the SMOA for the section.
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RE: Mean value of Second moment of area
RE: Mean value of Second moment of area
For every section I have one Second moment of area, I1 I2 I3 and I4, and the height H1 H2 H3 and H4. These sections is made out of equal angle steel members
Do I approached this problem the wrong way or is there any other method to calculate the total I of the beam
RE: Mean value of Second moment of area
RE: Mean value of Second moment of area
RE: Mean value of Second moment of area
RE: Mean value of Second moment of area
i think a hand calc will be very messy very quickly
an FE model should give you the answer. the euler load for a column is the first eigenvalue solution for the stiffness matrix, the following link describes this ...
http:/
RE: Mean value of Second moment of area
You could also just try applying bending and deflection theory by hand for the four sections which is not too much hassle. Don't forget to consider the way the deflection angles add up along the length.
From memory, castigliano's theorem is useful for this sort of problem - but I haven't used it in years.
gwolf.
RE: Mean value of Second moment of area
RE: Mean value of Second moment of area