Hi,
I have been designing post tension slabs for around 5 years, sticking to mainly 2D software in transfer situations and FEA for complex transfer slabs/flat slabs or flat plates. To date with no issues (touch wood!)
When I look at a simple office slab, for example 8m main spans, 6.5m end bays, with a 2400w, 350D post tension beam and 160 internal slabs spanning 8m with 200mm deep end bays,
The results differ when comparing 2D to 3D, and it begs the question, When Is a beam stiff enough to ensure one way action of the slab?
With post tension designs the level of reinforcement in shallow beams is nonexistent, with some minor negative reinforcement over the columns, Therefore if we are considering how the structure behaves if it is lightly reinforced are we
Allowing the concrete to crack in the slab, in line with the columns between beams in the top, and in the bottom mid span(Due to 2 way bending moments). As if this occurs then it will kick into the one way situation?. Which what we are designing for with 2D software?
I have been designing post tension slabs for around 5 years, sticking to mainly 2D software in transfer situations and FEA for complex transfer slabs/flat slabs or flat plates. To date with no issues (touch wood!)
When I look at a simple office slab, for example 8m main spans, 6.5m end bays, with a 2400w, 350D post tension beam and 160 internal slabs spanning 8m with 200mm deep end bays,
The results differ when comparing 2D to 3D, and it begs the question, When Is a beam stiff enough to ensure one way action of the slab?
With post tension designs the level of reinforcement in shallow beams is nonexistent, with some minor negative reinforcement over the columns, Therefore if we are considering how the structure behaves if it is lightly reinforced are we
Allowing the concrete to crack in the slab, in line with the columns between beams in the top, and in the bottom mid span(Due to 2 way bending moments). As if this occurs then it will kick into the one way situation?. Which what we are designing for with 2D software?