Thermal load applied to a composite beam?
Thermal load applied to a composite beam?
(OP)
Using RISAFloor and/or RISA3D, how does one apply a thermal load to a composite beam?
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Thermal load applied to a composite beam?
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RE: Thermal load applied to a composite beam?
RISA-3D can certainly apply thermal loads (to members or plates). The question really then becomes how do you choose to model your composite beam in RISA-3D. Along with what type of thermal load you are applying.
Is this just a uniform increase (or decrease) in temperature? In which case this would mostly result in axial forces or stresses developing in the system. Or, is there a change in temperatured from the top of the composite slab to the bottom of the steel beam or something along those lines? In which case there would be a good amount of moment created from the changes in temperature.
RE: Thermal load applied to a composite beam?
RE: Thermal load applied to a composite beam?
RE: Thermal load applied to a composite beam?
RE: Thermal load applied to a composite beam?
RE: Thermal load applied to a composite beam?
RISAFloor calculates the member's composite section properties, so, why not transfer that information into RISA-3D?
RE: Thermal load applied to a composite beam?
What should RISA-3D use as the "effective" area of the beam for axial stiffness? Should this area be different for tension vs. compression?
Then temperature loads add an extra level of complexity. Part of the area is due to concrete, part of it is for steel. What sort of thermal expansion coefficient should you use? Clearly, it would have to be weighted in some way based on the area of steel vs. the area of the concrete, but what method would you use?
What's worse is that because of the different expansion coefficients of the two materials, you will get differential expansion of the concrete and steel. This would induce a bending moment into the beam, wouldn't it? I cannot think of a reasonable way to model this short of building the composite beam out of plate elments and such per the Modeling Tips section I pointed out in my previous response.
In the end, RISAFloor is really designed to handle gravity type loading on typical commercial buildings. It's a great tool for that and can be expanded out into some other building sectors as well. But, the more you lean towards specialty loading (like thermal loads or bridge loading) the more you're getting away from that program's strong points and the more limitations you will encounter.