6.4m Portal Frame

[Contraflexure74]

Hi,

I've got a light weight roof spanning between portals, portals are @ 4.95m centres and the portal has a 2 degree mono pitched roof.

Dead is 0.9kN/m2
Live is 0.6kN/m2
Wind is 0.5kN/m2 (uplift)

The span of the rafter is 6.4m. Deflection governs and from my calcs I'm within the limits of span/360.

My rafter size is a 254x146x43UB. At a glance it seems a bit small (depth wise) but the numbers seem to stack up for deflection.

Anyone any thoughts on this?

For deflection I have modelled the rafter as simply supported but I guess I'm going to get some fixity at the moment connect at each end which may help limit deflection a bit? I'm not using haunches at each end of the rafters as the moments involved don't require them.

Any help would be appreciated.

John.

 

[apsix]

If you're not modelling a portal frame with rigid connections you're doing it wrong; have you checked for horizontal/sway loads?
Rafter size seems plausible.

 

[Contraflexure74]

Hi Apsix,

I have modelled it as a portal and the rafter deflections are even less which is good. I have also applied lateral loads to the frame.

John.

 

[rowingengineer]

Seems a bit oversized to me

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[apsix]

Size is generous, but so are the loads.

 

[Contraflexure74]

Thanks guys for all your help.

John.