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RE: Deflection Crteria

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The values of L/360 and so on are recommended minimums.  I recently
experienced the review from hell regarding deflection control.  The
building was a composite concrete deck on steel, design/build contract
office building.  The designer followed code allowables for sress and
deflection, but did not ponder the recommended guidelines for span to deth
ratios.  The building utilized 50ksi yield steel and minimum steel
sections.  The resulting 34 to 37 foot beam spans with 16 inch deep steel
sections .  The great flexibility of this system led to the overfilling of
the deck which resulted in a poor performing structure with reduced live
load capacities.  Additionally, the high beam end rotations and the
resulting cracks in the concrete deck at the face of the girders resulted
in poor performance of the girder composite action.  Even though the design
live load deflections met some initial criteria, the actual live load
deflections at mid span resulting from beam/girder deflections resulted in
partitions pulling out of their channel restraints attached to the
suspended cieling, deflection induced cracking and separation of wall panel
systems and roller coaster like deflections visible in the long corridors. 
Structure performance requires more than just evaluating to a standard.  It
involves evaluating how the magnitude of the deflections will be handled by
the architectural components and the motion perception of those sitting at
the desk on a bouncy floor.  Serviceability is the key to acceptable
performance and that is a function of perception not code performance.
Mark A. Scott, SE, Washington St.