Adding columns at mid span of crane girder
Adding columns at mid span of crane girder
(OP)
I am working on adding a column on a crane runway beam at mid-span. Anyone have experience with this so I know what to look out for?
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Adding columns at mid span of crane girder
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RE: Adding columns at mid span of crane girder
Under the girder?
Where is the column going?
RE: Adding columns at mid span of crane girder
Short span (25-30 ft), class D crane, 10 ton capacity.
RE: Adding columns at mid span of crane girder
RE: Adding columns at mid span of crane girder
RE: Adding columns at mid span of crane girder
RE: Adding columns at mid span of crane girder
Yep.
RE: Adding columns at mid span of crane girder
That's a pretty light crane.
I am having trouble thinking of any no-no's at the moment.
RE: Adding columns at mid span of crane girder
You'll of course have to do all the regular analysis as if the beam were continuous.
Placing the columns on the SOG seems like it might not work.
Also, you'll almost certainly want to put stiffeners in the girder web over the new columns. Stiffeners at supports are usually full depth. Intermediate stiffeners are usually terminated some distance from the tension flange due to fatigue.
RE: Adding columns at mid span of crane girder
Also - the subgrade under the slab may not be appropriate for the applied loads and you may have some settlement issues under the column.
Agree with the above about continuity over the column and a need to check for fatigue issues there. Also watch out for bracing required at the column/beam connection to avoid rotation and properly take out the lateral forces on the system.
RE: Adding columns at mid span of crane girder
RE: Adding columns at mid span of crane girder
Settlement or heave of the slab on ground will cause big issues with the crane - this is definately something you should steer them away from - provide proper footings.
One solution to some of the abovementioned issues would be to fix the base of the column to an appropriate footing and design it as a cantilever column.
RE: Adding columns at mid span of crane girder
I would want to weld, or bolt tight, the column to the girder before grouting the base with non shrink grout or, if that is too much trouble for a couple of columns, dry pack.
I haven't tried this, never had the necessity, but I have wondered about using an upside down king truss on the bottom of a beam that needed reinforcing. I know that some people have used wire rope and a center strut for this.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Adding columns at mid span of crane girder
Eight years later started having numerous end span connection failures with bolts, that could see tension when the crane was in the opposite bay, suffering fatigue failures.
Revised all of those connections and now at an additional 10 years in I expect to hear about fatige problems at any time.
Dr. Fisher discusses the pros and cons of simple span vs continuous crane runway girders in AISC's Design Guide No. 7. He recommends against continuous girders whereever fatigue needs to be considered.
gjc
RE: Adding columns at mid span of crane girder