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  • Change of Building Use




    I. Purpose of Investigation: 2 of 5

    Structural analysis of existing 250’ x 400’ building to determine suitability for Change of occupancy from Industrial to a combination of Assembly and Institutional.

    II. Description of Building:

    The building in question consists of two adjoining pre-engineered metal buildings. Building A dimensions are 250’ x 250’ x 24’ eave, symmetric gable 1/2: 12 roof. Building B dimensions are 150’ x 250’ x 24’ eave, symmetric gable 1/2: 12 roof. Building B was an add-on to the south endwall of Building A. The address of the building is 11345 West Century Circle, Springdale, OH.

    III. History:

    Construction plans indicate that building A was constructed in 1974, and building B was constructed in 1979, by the Contractor, for the Owner. The manufacturer of the buildings is uncertain. No manufacturer drawings are currently available.

    IV. Referenced Documents:

    2/1/74 drawings by Contractor. 3/15/79 drawings by Architect. 4/2/07 drawings by Contractor.

    V. Field Observations and Notes:

    Field inspections took place May 7, 2007, and May 14, 2007 for the purpose of reviewing the intended building modifications, and measuring the existing steel framing so that a structural analysis could be carried out.

    VI. Investigation Results:

    Current building code load requirements are shown in the Appendix of this report. Analysis has shown that gravity load is governing most of the building structural elements. Total gravity load considered is 4 psf dead, 3 psf collateral dead, and 22 psf snow, for a total of 29 psf. Also, current code calls for a region of the roof, 46 ft. wide, adjacent to the ridge, to be loaded with 27.4 psf snow, for a total of 33.4 psf.

    3 of 5

    Roof purlins:

    Issues of uncertainty which need to be resolved, in order to avoid potentially unnecessary reinforcement:

    1) The yield stress of the steel.

    Building A:

    The existing purlins are 10 span continuous (lapped), 8” light gauge steel zee shapes. Spans are nominally 10 @ 25’-0”. They are 5’-0” o.c.

    Field measurements indicate purlin material thicknesses of .095”, .090”, 6 @ .075”, .090”, .095”, from north to south, for the 10 spans.

    The building A purlins have been found to be adequate for the (basic) 28 psf loading, however, overstresses occur at the end of the laps when the (unbalanced) 33.4 psf loading is applied. This affects the first 10 purlins to either side of the ridge.

    Building B:

    The existing purlins are 5 span continuous (lapped), 10” light gauge steel zee shapes. Spans are nominally 5 @ 30’-0”. They are 5’-0” o.c.

    Field measurements indicate purlin material thicknesses of .085”, .090”, .090”, .090”, .085”, from north to south, for the 5 spans.

    The building B purlins have been found to be adequate for the (basic) 28 psf loading, however, overstresses occur at the end of the laps, in three locations, when the (unbalanced) 33.4 psf loading is applied. This affects the first 10 purlins to either side of the ridge.

    4 of 5 Main Frames:

    Issues of uncertainty which need to be resolved, in order to avoid potentially unnecessary reinforcement:

    1) The yield stress of the steel. 2) The web thickness of some of the rafter and column members. 3) The wall thickness of the interior pipe columns. 4) Sidewall columns need flange braces installed.

    Building A:

    The existing frames are 5 span rigid frames with column to rafter fixity at the sidewall columns. The frames are at 25’ spacings, with every other frame supported by jack beams at the (4) interior column locations.

    Building B:

    The existing frames are 5 span rigid frames with column to rafter fixity at the sidewall columns. The frames are at 30’ spacings.

    Endwalls:

    Building A:

    Rafter – was not able to access for accurate measuring, due to fire suppression interference. However, it seemed certain to be a 10” member. A 12 ga. , 10” cee is overstressed, so, it is likely to need attention.

    Columns – Both the 8” single cee and double cee columns are overstressed.

    Building B:

    Rafter – overstressed 57%.

    Columns – the 8” double cee columns are adequate.

    5 of 5 Longitudinal Bracing:

    Existing bracing is adequate.

    Wall Girts:

    All wall girts, except for the south endwall, are overstressed for current Code loads. This is likely due to significant Code changes since original construction.

    Foundations:

    Building A:

    Maximum soil pressure is 2700 psf. Original foundation plans indicate design was for 3000 psf maximum, however, no soils report is referenced.

    Interior column footings lack sufficient uplift resistance, unless burial is at least 3’-6” below floor slab. Original foundation plans indicate “varies 0’ to 5’.”

    Building B:

    Maximum soil pressure is 1300 psf for interior columns. Original foundation plans indicate design was for 3000 psf maximum, however, no soils report is referenced.

    Interior column footings lack sufficient uplift resistance, unless burial is at least 1’-8” below floor slab. Original foundation plans indicate “varies -verify.”

    Sidewall column footing detail indicates #3 floor tie to be installed. However, the original design calls for an unreinforced floor slab, which nullifies the effect of the floor tie for design purposes. The maximum soil pressure for the 3 ft square footings reach 5300 psf and 8600 psf, for the east and west walls respectively. This is a concern not due to increased loads for change in occupancy, as it was inherent in the original design.


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