6 Jun 12 12:09
I’m currently working on the analysis of the propagation of the temperature inside a composite steel-concrete bridge cross-section (when the air temperature is variable).
For this, I put myself into Ansys for the 2D thermal modeling of a symmetric cross section (two steel I-beams under a concrete slab). I used elements PLANE55 and designed only one halt of the section. The materials properties that I’m using are:
-Density: 7800 kg/m3 for steel and 2300 kg/m3 for concrete
-Specific heat: 465 J/(kg K) for steel and 900 J/(kg K) for concrete
-Thermal conductivity (isotropic): 54 W/(m K) for steel and 0.55 W/(m K) for concrete
Now, for the application of a convection load on the lines, I have to declare a film coefficient for the contact material-air. And that’s where I’m blocked. Does it depend on the sort of the material? What about the orientation of the line (vertical/horizontal)?
I was advised to use a value between 5 and 25 W/(m2 K) for free convection with air.
Am I on the good way so far?
And it would be very interesting if I could insert also a radiation load (equally variable – daylight), but I still don’t know how.
If someone could help me, it would be great!
Thank you in advance!