Braced Frame Lateral Shock Loading Connection Detailing in Arctic

[Bill Blarney]

Structure:
3-story industrial braced-frame tower, story heights ~= 0.85 square foot print dimensions.

Scenario:
Structure supports vertical loads on four columns, with lateral loads in *only one* direction.
One face supports twice the vertical dead load and live load of the other face, by load offset.
Normal to those two faces, lateral loads are shared in proportion to the vertical loads ~0.67g.

Question:
Structure to be craned into place as two pre-welded faces, then bolted together other two faces.
Which direction is best to shop weld as full face-frames, and which is best to erect by bolting,
the faces experiencing lateral loading? or the faces that experience only insignificant lateral?

Qualifier:
Structure experiences ~0.67g lateral loading every 24 hours, year in and year out, in the Arctic.

Alternates:
Or should it be all bolted with a bolting safety margin? Or erection-bolted, then field-welded?

Hoping there's some Arctic mining SME folks out there.

 

[E720]

What type of braces will be used? For the frames that will be assembled in the shop I don't think it matters. If it were me I would design for bolted in the other direction, but with an alternate weld calculated, meaning that if the bolt holes don't line up then they can weld it to the gusset. We do this all the time and clients love it. Usually what happens is they will bolt the bottom connection and weld the top. Just my 2 cents without knowing a whole lot about the Arctic situation.

 

[bones206]

I think it may be more of a logistical decision than a structural one. For remote site construction, you want to maximize shop fabrication within the constraints of what can be shipped and erected on-site. E720's suggestion is a good one - anything that makes field erection easier and provides contingencies to keep the job going is good on a remote site.

Since it's a repetitive shock loading, the connections for the resisting frame should be designed with fatigue in mind - especially welds. Toughness of the base metal and filler metal should be looked at closely due to the cold temperatures combined with dynamic loading. If there is potential for the shock loading to exceed the design load and damage the braces, maybe having bolted connections would be a consideration so that they can be replaced more easily.