Ansys: thermal analysis of a bridge cross section
Ansys: thermal analysis of a bridge cross section
(OP)
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!
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!





RE: Ansys: thermal analysis of a bridge cross section
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RE: Ansys: thermal analysis of a bridge cross section
Finally I applied only one film coefficient for both materials!
I’ll create a new thread at the Ansys section with a link for this one to see if I can get any help with the rest of the modelling!
Thank you!
RE: Ansys: thermal analysis of a bridge cross section
RE: Ansys: thermal analysis of a bridge cross section
Actually I don’t know the surface material temperature… I have a table with the air temperature every 10 minutes in 24h. The goal of my analysis is to get the variation of the temperature inside the bridge during a day.
With these results I’ll be able (I hope so!) to see the interference of a (possible) thermal gradient between the concrete and the steel at the bridge deformation.
The problem is that I need to suppose almost everything about the materials properties (we don’t even have the resistance of the concrete!).
RE: Ansys: thermal analysis of a bridge cross section