Concentrated Moments applied to Slab

[asixth]

Hi guys,

I have an existing suspended slab where a tensioned fabric structure is being install above. The prestress and wind loading on this membrane is resulting in a significantly large push-pull force ~=200kN (45kips) being applied to the slab.

In the sketch I have attached, how will this moment be resolved, will it be resolved as flexural bending between the columns or will it span as torsion between the column and loadbearing wall.

Also, the pullout force of the cable is getting too large for anchors embedded into the slab so I am planning on bolting through the slab and having two plates either side of the slab to resist pullout by the punching shear capacity of the slab. Will the bolt stud be getting too long if the slab is 450mm (18") thick in places.

 

[parrot77]

What loadbearing wall? A plan arrangement of the suspended slab showing walls and columns will be neccassary for anyone to comment

 

[DaveAtkins]

Is this a two way slab? If so, you must analyze the equivalent frame in each direction, separately, including the effect of the upward and downward point load from the cables and strut. I think in the left and right direction, the equivalent frame will see vertical point loads. In the up and down direction, the equivalent frame will see a concentrated torsional moment.

DaveAtkins

 

[hokie66]

asixth,

Firstly, I agree with using through bolts with a plate on the bottom for the tension cable anchorage. I wouldn't worry about the slab/band being 450 thick, except to try to miss the reinforcement. For the strut, through bolts are probably overkill, as you primarily need the bolts for shear.

I would just resolve the forces into horizontal and vertical. I would think it is unlikely that the horizontal forces would be a problem for the structure, other than resisting the shear at the connections.

The vertical upward forces at the cables and the downward vertical forces at the struts would be resisted as any other point loads in bending. I doubt that torsion comes into it.