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  • Sample report of a column base investigation


    COLUMN BASE INVESTIGATION


    I. Purpose of Investigation:

    At the request of contractor, Thomas R. Price P.E., of Structural Solutions LLC inspected
    the facility for the purpose of viewing column base distress in various steel framed
    buildings.

    II. Description of Buildings:

    The buildings in question are metal buildings manufactured by an MBMA manufacturer. For
    the purpose of this report, Building 12 will be used as a representative example of the
    various buildings in question.

    The example building is a 108' wide by 422" long x 14" eave, clearspan gable building with
    3:12 roof slope. (ref. Fig. A).

    III. History:

    Buildings were fabricated and erected in 1997.

    Concrete spalling at column bases and lateral shifting of the columns at their bases was
    observed by owner following snow build up on roof last winter.

    IV. Referenced Documents:

    MBMA manufacturer drawings.

    Pier Schedule and Footing Detail.

    Architect notes and sketches.

    V. Field Observations and Notes:

    The inspection took place between 10:00 pm and 1:00 pm. Our comments relative to the
    inspection of the column bases are listed below.

    1) Building sidewall column bases were observed to have translated laterally in the
    plane of the frame by as much as 3 inches. The (2) 1-1/4" dia. anchor bolts had
    been broken free of their bond to the concrete. The concrete between the anchor
    bolts and the edge of concrete was spalling off. Steel angle members were being
    welded to the column bases, hooking over the inside edge of the pier, in order to
    restrain further movement. Many columns were observed to be in this condition.


    VI. Analysis:

    Column base forces as provided by MBMA manufacturer drawings were used
    for calculations involving the foundations in question.

    Calculations show that, absent any reinforcement restraining the anchor bolts
    against lateral bursting, an edge distance of 15" is required. If adequate reinforcement
    were utilized to restrain lateral shear, a minimun edge distance of 5-1/2" is required.

    The calculated lateral strength of the as-built, 4" edge distance without restraining
    steel, is 9680 lb. The required strength is 39,600 lb. (Ultimate strength, factored
    loads) In our judgement it is this shortcoming that caused the anchorage distress.

    The hairpins ties to the floor may be considered to provide resistance to lateral movement
    of the footing. However, this resistance is limited to the floor area attributable to each
    column, and calculation shows this to be approximately 4500 lb. This is well short of
    the required 23,300 lb. (Service load).

    Review of the 4'-0" x 4'-0" footings, considered as 5'-0" x 4'-0" x4'-0" deep, and
    absent any hairpin restraint for purpose of calculation, shows excessive soil pressures
    (>10,000psf) and inadequate factor of safety against overturning. The weight of the
    footings plus grade wall and floor slab portions attributable to uplift resistance, are
    somewhat short of the required uplift resistance indicated by the manufacturer's
    foundation loads.

    Therefore, had the column piers held the load, or, if they are repaired in some way
    so as to hold the load, the effectively non-restrained footings would be overloaded.

    VII. Recommendations:

    A solution which addresses both the anchor bolt lateral bursting problem, and the
    footing overload problem is necessary. The repair detail by the architect does
    not adequately address all of the design issues, in our judgement.

    Existing piers must be cut out and re-poured per a new design. Anchor bolts must be re-
    placed in this pour. This is likely to be necessary in any proposed repair. Wind forces
    require uplift resistance of 18,000 lb, which is clearly not available with the anchor bolts
    in their current loosened condition. It should be noted that this lack of uplift resistance
    represents an existing danger of building failure under wind loading.

    The following pages outline three recommendations for remedying the anchorage
    problems. These recommendations are preliminary and not for construction. Final
    details of any agreed upon repair procedure are necessary prior to beginning work in
    the field.



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Structural Solutions LLC
1200 Troon Ct. SE
Grand Rapids, MI 49546
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