Steel Tube Beam to Steel Column Connection
Steel Tube Beam to Steel Column Connection
(OP)
I have a situation where I am analyzing a steel tube roof beam sitting on steel tube column. The beam is welded to the column. This is an interior beam and is not part of any lateral resistance system per the existing drawings. We are adding a new mechanical unit on the roof. If I design the beam with existing loads, it fails in the deflection criteria. I am assuming the connection to be simply supported. If I assume the connection to be fixed, it is okay in deflection. Is assuming the connection to be fixed correct since it is welded?






RE: Steel Tube Beam to Steel Column Connection
I would model the column as well to take into account the "partial" fixity there.
RE: Steel Tube Beam to Steel Column Connection
RE: Steel Tube Beam to Steel Column Connection
RE: Steel Tube Beam to Steel Column Connection
I would consider this pinned at the outside supports and fixed at the center support. A continuous member is the same as two fixed ends at the same support.
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RE: Steel Tube Beam to Steel Column Connection
RE: Steel Tube Beam to Steel Column Connection
For the question at hand, ensuring the roof does not pond is more important than insuring the D+L deflection is less than L/120. Footnote g in IBC table 1604.3 allows you to take the dead load as 0 with steel construction because it does not creep. But large dead load deflection may be noticed and the general public may think that the structure is overloaded or failing (and their perception is important).
RE: Steel Tube Beam to Steel Column Connection
Just an idea, often when we add RTU's to a structure post-construction, we stub up directly from the columns and build an independent frame. This eliminates any contribution of our system to the roof and transfers everything directly to the columns.
PE, SE
Eastern United States
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RE: Steel Tube Beam to Steel Column Connection