Novice in need of HELP!!
We are cutting a hole in a floor of an existing building for a new stair. I'm calculating that this will cause a great deal of torsion in the beams that run along the sides of the opening--mainly because I'm assuming we are removing their torsional restraint. I'm hoping this assumption is an overconservative mistake, and that the beams will be okay. More explanation below:
The floor slab that we're cutting into is 6" reinforced concrete. It spans 7' to the secondary beams, which are W12X30's. The W12X30's span 17'. We plan to cut out an entire section of floor (the opening will be just less than 7'wide by 17' long). The remaining W12X30's will still support the sections of floor that remain along the outside of the opening.
I'm calculating that if these beams are considered to be unrestrained, that the load from the remaining floor will cause torsion in the beam. I've assume that since the beams would no longer be connected to the removed section of floor, that there would be no torsional restraint (this is where I think I may be making an overconservative mistake). With this assuption plugged into my model, I'm calculating that there would be severe rotation and torsional failure--even when I'm just looking at the slab dead loads.
Have I made the correct assumptions, or should I retry my model, assuming that the remaining portion of the slab (the one delivering the torsion) could also act as a torsional restraint.
THANKS EVERYONE FOR YOUR TIME AND HELP!!!!
We are cutting a hole in a floor of an existing building for a new stair. I'm calculating that this will cause a great deal of torsion in the beams that run along the sides of the opening--mainly because I'm assuming we are removing their torsional restraint. I'm hoping this assumption is an overconservative mistake, and that the beams will be okay. More explanation below:
The floor slab that we're cutting into is 6" reinforced concrete. It spans 7' to the secondary beams, which are W12X30's. The W12X30's span 17'. We plan to cut out an entire section of floor (the opening will be just less than 7'wide by 17' long). The remaining W12X30's will still support the sections of floor that remain along the outside of the opening.
I'm calculating that if these beams are considered to be unrestrained, that the load from the remaining floor will cause torsion in the beam. I've assume that since the beams would no longer be connected to the removed section of floor, that there would be no torsional restraint (this is where I think I may be making an overconservative mistake). With this assuption plugged into my model, I'm calculating that there would be severe rotation and torsional failure--even when I'm just looking at the slab dead loads.
Have I made the correct assumptions, or should I retry my model, assuming that the remaining portion of the slab (the one delivering the torsion) could also act as a torsional restraint.
THANKS EVERYONE FOR YOUR TIME AND HELP!!!!