Beam off grid line ???

[Brim]

Hi there,
I'm doing the design 3 stories rc. building but according to the architectural concept , he wants to build the brickwall 3.0 m height off grid line about 0.60 m to hide the column from outside view and want to have a recess floor in these part to be the rest room. Firstly I decide to design a cantelever slab span 0.60 to pick up the wall but I got a problem with the recess floor becuase there is some parts to be the recess floor not the whole length of building and the I think if I move my supporting beam which perpendicular to the distance 0.60 m. to support the brickwall at the edge of building and be supported by short cantelever beam from columns and where there is a recess floor I will put the intermediate beam right to this supporting beam to support it... I think it's alright but I' worried about lateral stability because of the supporting beams are not on grid line (they are 0.60m off grid line) and only cast in place slab 0.10 m to connect column between grid line, is it alright? or I have to concern anything? .... Please help me
Thanks
Brim

 

[ishvaaag]

I think the best solution if nothing opposes it is to put a beam supporting the inner part parallel to the façade and then whatever protrusions in plan, whether with walls or only parapet or railings be taken in cantilever from the beam. We use this solution systematically, if only because in practice many times the point of support at the outermost façade walls would fall in the street.

As long the cantilever is proportionate one needs not to expect special problems; sometimes a hairline crack develops even in these, but this is more common when the number of strories goes high and the length of the cantilever becomes significant.

But you must make the thicknesses of such size as to no deflection problems develop. For example, 10 cm thickness for a 60 cm cantilever loaded by a wall might show some deflection distress that analysis of the deflections should show.