STRUCTURE PROBLEM
STRUCTURE PROBLEM
(OP)
Greetings everyone
i have attached a picture of my problem...
i want to know how can i calculate bending moment for the same.????
how can i calculate moment of inertia and center of gravity for structure(made of channels and beams) shown????
as i think if i can calculate the above mentioned it will be easy to check whether my design can take that load or not
i have attached a picture of my problem...
i want to know how can i calculate bending moment for the same.????
how can i calculate moment of inertia and center of gravity for structure(made of channels and beams) shown????
as i think if i can calculate the above mentioned it will be easy to check whether my design can take that load or not






RE: STRUCTURE PROBLEM
as a hand calc, i'd start with the reactions, it looks as though the load is slightly right of Centre, so the three reactions on the left side will be slightly higher than the three on the right, maybe 55:45; the middle reactions are going to be highest and the far end, away from the load, may be -ve ... that's how it'd be if the side edge beam worked as a beam, but looking as a grillage (sort of like a plate) then they'd be +ve (ie up).
then you've got what looks like two beam setions to stress.
RE: STRUCTURE PROBLEM
I don't know exactly what this frame is for, however, I have done plenty of frames that support large roof top equipment that look similar to this. Normally the connections at the end of the beams are simply supported. I apply the loads on the beams and then calculate moments and deflections. Then I would make a model in the computer and check to make sure my calculations were correct.
RE: STRUCTURE PROBLEM
Brad
RE: STRUCTURE PROBLEM
RE: STRUCTURE PROBLEM
This should probably be framed with the deeper, continuous members running the short direction to girders across the long sides. This would get the load to all of the supports according to the location of the load, and would reduce deflection significantly, member sizes being equal.
To reach a more accurate answer using software, make the ends of smaller channels pinned. This will place the main load on only the four long channels under it.
RE: STRUCTURE PROBLEM
This could easily be done by hand calcs, if the 16 ton load is evenly distributed.
If the short beams are pinned, it's a piece of cake.
tg
RE: STRUCTURE PROBLEM
its actually a kinda chassis that carry load from one place from other
what i got in mind to calculate Moment of inertia and center of gravity of whole structure and hence i can get section modulus of whole structure
and by calculating maximum bending moment i can equate both to get maximum bending stress
tell me if m wrong???
but i dont know how to calculate Moment of inertia, COG and bending moment...
if there s better way please share??
i will be highly indebted if anyone can do rough calculation for same
or can anyone suggest a better software for analysis??
i use catia... is catia a better software to do analysis??
thanx
RE: STRUCTURE PROBLEM
that does IMHO make any sense. if this is your thinking, then i suggest you need to review mechanics of solids texts.
you need to analyze the loadpaths, the individual beams. you have lots of asusmptions to make if you're going to hand calc this ...
1) you could assume that the short beams distribute the load the the long edge beams, and the long beams take these loads to the corners.
2) you could assume the corner reactions (from solving the structure as a whole) and then devise internal loads that make each member balance.
3) then you'll have the maximum moment in each member and you can analyze each loadpath.
4) you can simplify by assuming each joint is a pinned connection.
5) you can use the minimum number of beams to be conservative.
...
RE: STRUCTURE PROBLEM
RE: STRUCTURE PROBLEM
Make sure though that you restrain the moment at every connection. Company where I work everything would be wellded all arround fillet therefore resisting bending.
RE: STRUCTURE PROBLEM
You're wrong!
Beams in the vicinity of the load will carry more than those further away. Properties of the whole structure would give incorrect values of bending stress.
BA
RE: STRUCTURE PROBLEM
This could even be reduced to 3 separate beams to design, because the shorter perimeter beam that is far from the load could be made the same section as the closer one for simplicity.
tg
RE: STRUCTURE PROBLEM