My building has the first suspended floor and free ground composed of pilotis. I would like to know how to represent how this first floor can be suspended by pilotis
If your pilotis is an open space, the boundary condition of the floor should be outdoors, wind exposed but not sun exposed. You should also take into consideration the thermal bridge effects from the columns beams etc so as to increase the U-value of your floor construction accordingly
What is the correct way to calculate U-value impact of the column? Typically we assumes surfaces transfer heat in 1D (perpendicular to surface plane) given negligible heat transfer parallel to construction layers. For 2D thermal bridging (windows,studs) where we account (by projection from 2D to 1D) for 2D impacts, we still assume heat transfer is negligible in surface plane and only take 2D slices perpendicular to it, or do area-weighted calculations.
I can't quite figure out the correct way to conceptualize column heat transfer because this 2D assumption doesn't hold.
There are some posts in the forum that adress this issue. For example: Thermal Resistance of Linear thermal bridges Calculating 3D Thermal Bridges How to include thermal bridges in the analysis in the OpenStudio - EnergyPlus? and others. If these doesn't help, you should probably post this as a new question
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@jhonata2187 to confirm, are the pilotis that you're referring to vertical piers, columns, stilts, etc.? If so, do you have any floor surfaces touching soil or are all floor surfaces suspended above ground by pilotis? You should have enough karma to add an image to your post to help illustrate what you want to simulate.
Pilotis are a typical solution of Modern Brazilian Architecture, where the body of the building is suspended from the ground, leaving only its pillars in the gap... But in an elegant way... https://encrypted-tbn0.gstatic.com/im...