cantilever balcony 5

[aldincrump]

is it possible to design a cantilever slab with a uniform load along it free end using a simple supported beam as the point of fix support

 

[hokie66]

As I understand your question, there would be no backspan for the cantilever. If that is the case, the beam would have to be capable of resisting the torsion imposed by the cantilever, so could not be simply supported in terms of rotation.

 

[aldincrump]

thanks for the quick response .yes you are correct there is no back span.therefore if the beam is fixed then it is posible to design the cantilev beam using the beam as the only point of support

 

[BAretired]

If hokie has interpreted your question accurately, then I agree with him. However, I am not really sure that I understand your question. Maybe a sketch would clarify things.

BA

 

[pwht1]

Had to read through this one a few times... If this is a concrete balcony, why don't you have a backspan? How do people access the balcony and what is the floor material? Sorry to go off track, but you got me wondering.

Yes, if the beam is torsionally restrained at each end and has the capacity you can cantilever the slab off the beam.

 

[aldincrump]

hi Ba i have uploaded a pdf of the section and plan view showing the problem.pwht1 you are correct it not really a balcony please have look at the drawing

 

[aldincrump]

here are the others

 

[aldincrump]

this is final one section view

 

[DaveAtkins]

From the Section, the "balcony" looks more like a decorative appendage that you cannot even stand on. I would use floor to floor posts and attach the appendage to them.

DaveAtkins

 

[Ron]

It appears from your sketches that you have variation of a "Juliette" balcony, but without any access.

Yes, the beam can be designed to handle the torsion...it is similar to a cantilevered canopy overhang on the side of a building. As others have noted, the ends of the beam will need to be fixed. You can also make the railing a structural component to help out.

 

[hokie66]

Glad Dave could figure out where the "balcony" is from those drawings, because I couldn't.

 

[Ron]

hokie66...I thought I was the only one having that problem. Finally figured it out (I think).

In the elevations, the balcony is on the far right of the upper elevation drawing. In the plan view, it is the 24'-5+/- section at the lower part of one of the plan views. The plan views and elevations do not correspond in orientation.

 

[DaveAtkins]

Ron,

I don't think the floor beam will be loaded in torsion, because the balcony is above the floor by a couple of feet.

DaveAtkins

 

[aldincrump]

hi dave the challenge is that the archtect want the area to cloumn free

 

[DaveAtkins]

Why can't you have two posts going floor to floor and contained within the exterior wall?

DaveAtkins

 

[BAretired]

I have the same problem as hokie, even with explanation from Ron. I thought maybe aldincrump was referring to the curved thingy at the right of the plan, the support of which seems a bit uncertain.

The only really useful information I can give is that "Pearl Vision" should be spelled "Pearle Vision". I know 'cause that is where I got my glasses last time.

BA

 

[aldincrump]

many thanks guy and gals for all the usefully and sometimes humours suggestions.I will have dialouge with the archtect to arrive at some comprise.I have also been having problem visualising the structural frame myself for that curve section of the plans

 

[Ron]

Dave..I think something is hidden in his sections. If you look at one location, it appears to be at the floor level.

In any case, this is an exterior exposed "balcony" that juts out from the face of the building and picks up an overhang wind load (in an area of 150 mph wind speeds), so there will be torsion on whatever it is attached to, assuming he can't add hangers, posts or some other ancillary attachment.

If it were just a floor extension is would be no big deal, but apparently that is not the case.

ALSO...BAretired pointed out the spelling error on "Pearle". Op[highlight]h[/highlight]thalmologist is also spelled incorrectly...there should be another "h" in there as highlighted.

 

[aldincrump]

hi guy here is another drawing this make the section clearer
this is the roof plan the section is cut from the roof down to the first floor

 

[aldincrump]

what i was trying to achieve was a structural framing system for the building and found it challenging because of the limitation .the archtects wants the space to be column free as possible. That is why i wanted to cantliver the lower slab feature and then use that slab to support the upper roof.hence the intial question was ask in the forum