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Thread: Stair Framing: Primary Structural Frame or Not?

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    Sawhorse RLGA's Avatar
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    Stair Framing: Primary Structural Frame or Not?

    Assumption: Table 601 requires a fire-resistance rating for primary structural frame.

    Couple of conditions:

    Interior Stairs: Located within an exit enclosure. Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and does not support the enclosure walls.

    Exterior Stairs: Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and is exterior of the building envelope (i.e. free-standing with landings connected to building).


    Would you consider one or both of the two conditions part of the "Primary Structural Frame" as defined by the IBC? The definition is not clear in this respect, so I'd though I'd get some opinions.
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    Sawhorse
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    I would say no...as the stairs do not resist any forces (wind, snow, seismic I guess) or support anything but themselves (and the users of course)....wouldn't be the first time I was wrong.....just the first time today....
    Please support Jim Brown, Deputy Building Official from Gillette, Wyoming for ICC Board of Directors.
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    I see what you’re asking and would say... I would consider the columns of the self supporting stair and the landings connected to those columns as primary construction, even though they are not apart of the building they still need to resist gravity loads.

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    Quote Originally Posted by gbhammer View Post
    I see what you’re asking and would say... I would consider the columns of the self supporting stair and the landings connected to those columns as primary construction, even though they are not apart of the building they still need to resist gravity loads.
    So does the hanger for a sink.

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    PRIMARY STRUCTURAL FRAME. The primary structural frame shall include the following;
    1.The columns;
    2.Structural members having direct connections to the columns, including girders, beams, trusses, and spandrels;
    3.Members of the floor construction, and roof construction having direct connections to the columns; and
    4.Bracing members that are essential to the vertical stability of the primary structural frame under gravity loading shall be considered part of the primary structural frame whether or not the bracing member carries gravity loads.

    [QUOTE=RLGA;77473]
    Interior Stairs: Located within an exit enclosure. Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and does not support the enclosure walls.

    Exterior Stairs: Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and is exterior of the building envelope (i.e. free-standing with landings connected to building).


    QUOTE]

    They have columns, and floors directly connected to those columns, perhaps even bracing members essential to vertical support. Primary structural framing does not mean the shell of the building. A building is a srtucture a structure may not be a building. Primary refers to the part of a structure that resist gravity loads.

    A sink and its hanger has none of these things but would provide a nice place for the puke you generate sometimes.

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    Sorry about that brudgers the daughter and I have had the stomach flue and puke has been on my mind a lot the last two days.

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    Sawhorse Codegeek's Avatar
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    I'm with steveray on this. I'd say no they are not primary structural frame members. They may be part of the secondary members though.
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    Quote Originally Posted by RLGA View Post
    Assumption: Table 601 requires a fire-resistance rating for primary structural frame.

    Couple of conditions:

    Interior Stairs: Located within an exit enclosure. Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and does not support the enclosure walls.

    Exterior Stairs: Steel framing for stairs (consisting of columns, stringers, etc.) is independent of the building frame and is exterior of the building envelope (i.e. free-standing with landings connected to building).


    Would you consider one or both of the two conditions part of the "Primary Structural Frame" as defined by the IBC? The definition is not clear in this respect, so I'd though I'd get some opinions.
    I would say they are not part of the Primary Structural frame. They are not a fundamental component of the building construction.

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    I would definetely not slight their importance,....but if they were considered primary..might they need to be rated per Table 601? Just as a different perspective....
    Please support Jim Brown, Deputy Building Official from Gillette, Wyoming for ICC Board of Directors.
    My questions and answers are based on some bastardized hodge podge starting with the 2003 I-codes amended by the state of CT in 2005 and 2009 including the 2005 NEC ....and as of today.....The 2011 Connecticut Amendments to the 2009 International Energy Conservation Code portion of the 2005 State Building Code has been posted to the State Building Inspector’s website

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    Sawhorse north star's Avatar
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    &

    If the stairs are part of the MOE, then I would say "yes" they
    would be required to be fire protected.

    From the `06 IBC:
    EXIT. That portion of a means of egress system
    which is separated from other interior spaces of a building or
    structure
    by fire-resistance-rated construction and opening
    protectives as required to provide a protected path of egress travel
    between the exit access and the exit discharge.......Exits include
    exterior exit doors at ground level, exit enclosures, exit passageways,
    exterior exit stairs, exterior exit ramps and horizontal exits.......IMO,
    this would also include any interior stairways designated for the MOE.

    =
    Last edited by north star; March 14th, 2012 at 13:16.


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    Quote Originally Posted by steveray View Post
    I would definetely not slight their importance,....but if they were considered primary..might they need to be rated per Table 601? Just as a different perspective....
    Yes they would be required to be rated if they were considered that way.

    However, such consideration would be incorrect.

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    Sawhorse Codegeek's Avatar
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    If the stairs have elements which connect to the columns or other structural elements, then they would be considered primary structural members. From what the OP states, it appears they do not, so they would not be primary structural members. Yes, the stairs may have gravitational forces on them, but they are not part of the primary structural members.
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    Sawhorse north star's Avatar
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    =

    Does the term "primary structural members" hinge on means of attachment,
    or use?......Either way, the MOE stairs would still require fire protection.

    =


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    Sawhorse Francis Vineyard's Avatar
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    The new requirement clarifies the intent that the primary structural columns are individually wrapped or protected and other frame members can continue to be protected within the fire-resistant membrane assembly. The fire-resistance of the stairway framing was not affected.

    Francis
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    Quote Originally Posted by north star View Post
    =

    Does the term "primary structural members" hinge on means of attachment,
    or use?......Either way, the MOE stairs would still require fire protection.

    =
    This is from the 2009 IBC Commentary - "This category includes the structural (load-bearing) components of the building frame. Definitions of “Primary structural frame” and “Secondary members” are found in Section 202. Any structural item that provides direct connections to columns and bracing members that are designed to carry a gravity load is considered part of the structural frame."

    It goes on to say, "Secondary members (e.g., floor or roof panels without a connection to the column) are not considered part of the structural frame."

    The definition of secondary members -
    "SECONDARY MEMBERS. The following structural members shall be considered secondary members and not part of the primary structural frame:
    1. Structural members not having direct connections to the columns;
    2. Members of the floor construction not having direct connections to the columns; and
    3. Bracing members other than those that are part of the primary structural frame."
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    Quote Originally Posted by Codegeek View Post
    If the stairs have elements which connect to the columns or other structural elements, then they would be considered primary structural members. From what the OP states, it appears they do not, so they would not be primary structural members. Yes, the stairs may have gravitational forces on them, but they are not part of the primary structural members.
    Primary Stucture does not mean the building.

    Primary structure = column/elements that supports vertical structure from gravity loads.

    The stair is a structure that resist gravity loads

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    All right I agree with ya'll now after seeing the secondary structure def.

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    Sawhorse
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    Sorry for throwing in that rating thing....I think I muddied it up a bit....I was just trying to make the point that if they were considered part of the primary structure, the stairs themselves would need to be rated (by table 601 me thinks), as well as the vertical exit enclosure....maybe I am wrong, but I have never seen 1 hr stringers inside a 1 hr enclosure...
    Please support Jim Brown, Deputy Building Official from Gillette, Wyoming for ICC Board of Directors.
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    Sawhorse Francis Vineyard's Avatar
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    In reference to the OP conditions; if the "independent" supporting columns for the stairs where to be individually wrapped in fire-resistance protection with the stairway exposed to extreme heat; would render the protection application and exit useless.

    Francis
    Last edited by Francis Vineyard; March 15th, 2012 at 05:33. Reason: add word
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    Sawhorse TheCommish's Avatar
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    http://www.inspectpa.com/forum/showt...numental-stair

    Not fire resitive but non combustable 2009 IBC 1009.6 Stairway construction. All stairways shall be built of materials consistent with the types permitted for the type of construction of the building, except that wood handrails shall be permitted for all types of construction.

    Then SECTION 603 COMBUSTIBLE MATERIAL IN TYPE I AND II CONSTRUCTION 603.1 Allowable materials. Combustible materials shall be permitted in buildings of Type I or II construction in the following applications and in accordance with Sections 603.1.1 through 603.1.3: the list 25 allowance and exception none of which are stair stringers, guards or supports
    Code compliance and inspections, leads to non-events


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