Discussion: View Thread

  • 1.  Application of Provision 4.7.3

    Posted 12 days ago
    have a technical question about provision 4.7.3 in ASCE 7-22 (see provision below).
    "4.7.3 Heavy Live Loads Live loads that exceed 100 lb/ft2 (4.79 kN/m2) shall not be reduced.
     EXCEPTION: Live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20%, but the reduced live load shall not be less than L as calculated in Section 4.7.2."
    Suppose there is a 1st floor column of a 3-story building that supports 2 floors (not including roof) which have a live load = 125 psf, and you want to find the axial live load in the 1st floor column. I have seen some sources state that the 2nd floor live load can't be reduced because the 2nd floor column only supports 1 floor,  but the 1st floor live load can be reduced since the 1st floor column supports more than one floor. 
    Other sources have the live load on both floors reduced since the first floor column supports 2 or more floors, and that is what the axial load is being computed for.
    What is the correct methodology to applying this provision?


    Grady Mathews P.E.
    Assistant professor
    Penn State Harrisburg
    Middletown PA

  • 2.  RE: Application of Provision 4.7.3

    Posted 11 days ago

    The first interpretation is correct.  Each story-length of column is treated as a unique element.  In this case, the first story column supports two floors and the second story does not.

    Ronald Hamburger, SE
    Consulting Principal
    Simpson Gumpertz & Heger