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Re: UBC Live Load Reduction

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I haven't heard that point of view before.  UBC 1607.5 states that it applies to "any member supporting more than 150 square feet", which wouldn't seem to exclude a footing, provided it has sufficient tributary area.  1607.6 specifically provides, in the AI definition, for values for columns.  Since the footing is loaded by the column, and typically the column load is used for the footing design, it is difficult to see why a recalculation of the LL would be called for as the load passes through the column/footing cold joint.  Based on the theory behind LL reduction, the two loads would be expected to be the same since the tributary areas are the same.  I also notice that 1607.6 states that it is given "as an alternate to Formula (7-1)", which could be taken to mean that the preable to 1607.5 still applies except to the extent that (7-1) is superceded by (7-3) for that section.  Good luck.  

>>> "Bill Allen, S.E." <T.W.Allen(--nospam--at)> 05/13/05 09:03AM >>>
O.K., I realize I haven't worked with the building code for very long
(tongue firmly planted in cheek), but I recently received a set of plan
check comments including one that has caught me off guard.


The plan check comment is as follows: "The live load reduction shall not
apply to the footing design." I called the plan reviewer (outside
consultant) to find out the section of the code which states this and he
told me section 1607.4 and 1607.6. I scanned these two sections during our
telephone conversation and still could not find where it said that I could
not take a live load reduction for the footing design. He told me that the
referenced sections stipulate live load reduction for beams and, since it
does not specifically permit a live load reduction for footings, no
reduction can be made. I hung up (politely) almost in shock and read the
referenced sections again. I know I'm not a good reader (otherwise I would
be an attorney), but the sections read (to me) "structural members", not
"beams". I thought a footing was a "structural member", but if not, why did
he not cite columns as well?


Anyone else have an interpretation?




T. William (Bill) Allen, S.E. (CA #2607)


Consulting Structural Engineers


V (949) 248-8588


F (949) 209-2509


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