26m beam

[sybie99]

I have a project where we need to construct a 26m beam, in situ. precast T beams wont work as we cannot get a crane access to lift them.

I will be able to provide a back span of about 12m which will help a lot, can probably get away with a 1.8m deep beam, 850mm wide.

I have never designed or seen a beam of such length constructed. In theory I don't see a problem. But is there anything to look out for?

The beam will be supported by 12m high columns, about 850sq, designed to carry moment induced by beam.

Just thought let me post it here and get comments, maybe in situ beams of such nature have intricacies in design or construction I am not aware of.

Thanks

 

[Ingenuity]

Do you have access to post-tensioning systems?

What is the purpose of the beams - simply roof beams, or other loadings too?

 

[sybie99]

Ingenuity, it forms a floor for a retail store, no high point loads, mainly udl from floor loads.

If possible we want to stay away from PT as the interface with the in situ slab creates problems for the contractor

 

[dik]

You may want to revisit using post-tensioning... appears to be an ideal type of solution... if possible install 'dead end' at the insitu slab... long span, uniform loads... sounds pretty good to me. Minimise depth and accommodate long term deflections.

Dik

 

[Ingenuity]

What is the magnitude of the spans for the floor slabs framing transversely into the beam?

 

[hokie66]

sybie,

Not sure what you mean about the "interface with the insitu slab". If the beam is post-tensioned, the normal course of events is for the slab and beam to be cast monolithically.