Portal Frames 1

[civeng80]

Does anyone have any knowledge or can they comment on industrial buildings with concrete tilt panels connected to rafters (either UB or open web trusses) with rigid connection to the panel so that the concrete panel (or part of it) acts as a beam column and where shear walls are not possible at the ends of the building (e.g. because of large openings). If so what would be the effective column width of the column/panel?
Can anyone tell me if there is any software/literature available on this subject?

Thanks !!

 

[civeng80]

Actually the above connection would be difficult/impossible to erect on site.

Cheers!

 

[hokie66]

1. The connection as I described can be erected. The two angles on the wall are outside the rafter flanges. Each would have at least 2 bolts into the wall, depending on the load. No need to slope the bearing surface, angle on rafter will also be horizontal.

2. The angle on the rafter would typically be one piece, with the inside of the vertical leg welded to the end of the rafter web, and the horizontal leg slotted through the web and welded both sides.

3. Connection doesn't have to be at bottom, could be near the top. Just watch things like edge distance to top of wall. Waler needs to be in bracing plane.

4. Restraint of top flange in completed structure will be primarily by purlins, but I think some restraint is required for erection of deep sections. The method of providing this restraint also may depend on other details of your building like box gutters, downpipes, etc.

I am not saying this is the only way of detailing this connection. Just trying to point out one way and some of the problems which can be encountered if the details are not thought through well.

 

[civeng80]

OK Hokie66 I think Im with you now on the connection. The 2 angles on the wall are outside the flanges so theres no erection problems. The connecting angle on the web is slotted in the web of the rafter and prodrudes past the flanges to sit on the angle seats. A neat connection. But what if the rafter has a grade ? Bottom legs of the angles would need to be graded right (unless Im missing something here !)

Cheers and thanks for your interest ! I may never use this connection but still very interested in the detail. If you dont mind I may detail it up and post it to make sure its what your describing.

 

[civeng80]

Ok its fine all angles may be kept horizontal. A neat connection. Probably better for the deeper sections as you said. Eliminates prying on the panel since all bolts are horizontal.

Thanks !

 

[hokie66]

civeng80,

Glad you found my advice interesting. Would have been better if I could have sent you a sketch instead of describing it in words, but never mind, we worked it out. Good luck on your projects and a Happy New Year.

 

[civeng80]

Thanks hokie66

Its fortunate that we engineers use drawings to convey much of our information as words can sometimes be so confusing and misleading. Thanks again !

Likewise a Happy and successful new year to you and yours!

 

[csd72]

civeng80,

Is it possible that the portal frame is designed as a T-shaped rigid frame with rigid connections to the central column and only pinned connections to the external panels.

I did renovation work on a bunnings warehouse that was designed exactly that way. The panels then act like mullions at each end resisting the compression/tension from the beam reaction. The central column needs to be twice as stiff though.

 

[civeng80]

csd72

Ok but it required a steel column in the centre with moment connections, what sort of spans were involved here?

 

[csd72]

At least 15m probably more like 20m each span.