Erection load case for steel frame
Erection load case for steel frame
(OP)
Hi,
I've been asked to design a steel frame for sway during the erection load case. In the permanent load case the frame will be braced by rc cores. My issue is the builder wants to erect the frame before the cores are built.
My question is what load do I apply to the frames to design bracing members during erection and is there a rule of thumb in terms of the distances between braced bays as my building is 150m long?
John.
I've been asked to design a steel frame for sway during the erection load case. In the permanent load case the frame will be braced by rc cores. My issue is the builder wants to erect the frame before the cores are built.
My question is what load do I apply to the frames to design bracing members during erection and is there a rule of thumb in terms of the distances between braced bays as my building is 150m long?
John.






RE: Erection load case for steel frame
RE: Erection load case for steel frame
RE: Erection load case for steel frame
Depending on the structure and exposure period, you might also consider wind load with a lower design return period (per ASCE 37 or local experience)
RE: Erection load case for steel frame
RE: Erection load case for steel frame
RE: Erection load case for steel frame
RE: Erection load case for steel frame
RE: Erection load case for steel frame
Have never heard of the shearcore being built after steel framing in this order. Interesting challenge.
A few factors would influence my decision on this:
---Is the RC core indeed the ONLY permanent LRFS element?
---How many stories? RC core implies 4 or more.
---Will the floor decks (presumably composite steel) be poured in advance of the RC core?
Assuming the worst (4+ stories), decks poured, no other lateral---you need to create a lateral system without the core. Knee brace kickers and/or temporary braces, or possibly X-braced cables, are some options that come to mind. The braces should be added prior to concrete floor pours, which cause the potential for racking (as well as adding seismic load).
As Willis pointed out, the GC will quickly learn why most buildings don't go up in this order.
Use 70% of wind for temporary loading (1 year or less). I'd just use your Equivalent Lateral Force Cs value for seismic.
RE: Erection load case for steel frame
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Erection load case for steel frame