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    C H A P T E R   3

    METAL DETAILS

    3-1   STRUCTURAL STEEL COLUMN

    ERECTION TOLERANCES

    Description

    Figure 3-1 illustrates some of the erection tolerances permitted by the American Institute

    of Steel Construction (AISC) for the plumbness of columns and attached spandrel beams.

    Along with the mill tolerances and plan tolerances shown in Section 3-3, this diagram permits

    realistic detailing of the attachment of other materials, such as exterior cladding, to a steel

    frame. However, AISC 303 states that the accumulated mill and fabrication tolerances cannot

    cause erection tolerances to be exceeded.

    Figure 3-1 shows the permissible envelope within which the working points of columns

    can fall. When misalignment of beams is caused by an acceptable variation in column align-

    ment, the beams are considered acceptable as well. Figure 3-2 illustrates the permissible

    variations of a beam attached to a column, which is within the allowable tolerance envelope

    shown in Fig. 3-1.

    In general, with the tolerances shown in Fig. 3-1, if connections that allow for a 3 in.

    (76 mm) adjustment are provided, the exterior of a building (the building line in the detail)

    can be maintained in a true vertical plane up to the 20th story. If no further adjustment is

    provided in buildings of over 20 stories, the exterior can be maintained within  1/16 in. (1.6 mm)

    per story.

    Limitations of Use

     Additional tolerances exist for steel fabrication and erection. Refer to AISC 303,  Code 

    of Standard Practice for Steel Bridges and Buildings, for a complete description.

     Figure 3-1 does not account for differential column shortening between interior and ex-

    terior columns during construction or for the effects of temperature changes. However,

    once the building is complete, these variations are usually not significant for detailing

    purposes as long as sufficient clearance and adjustment have been provided based on

    the tolerances shown in this detail and in Section 3-3.  Figure 3-1 does not indicate mill tolerances for camber or sweep.

    143

     Architect’s Handbook of Construction Detailing, Second Edition

     by David Kent Ballast

    Copyright © 2009 John Wiley & Sons, Inc.

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    144   A r c h i t e c t ’s H a n d b o o k o f C o n s t r uc t i o n D e t a i li n g

    Figure 3-1 Structural steel column erection tolerances 05 05 03

    allowable plumb  line tolerances

       b   u

       i   l    d    i  n   g

       l   i   n   e

    varies

    max. slope 1/500 between working points

    column line

    plumb

    20th floor

    36th floor

    2" (50) 3" (75) for exterior columns

    max. slope 1/16" (2) per story for exterior columns

    1/4" (6)

    base W.P. tolerance

    See Sec. 3-2

    varies

    plumb

    1" (25)Tt=

    1/4" (6)

    2" (50)aT =

    Detailing Considerations

     The following definitions apply to steel erection tolerances:

    The working point of a column is defined as the actual center of the column at either 

    end of the column as shipped. Therefore, when two column pieces are spliced together,

    there are two working points adjacent to each other.

     The working point of a beam is the actual centerline of the top flange at either end.

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    M e t a l D e t a i l s     145

     The mill tolerances shown in Section 3-3 should be added to the erection tolerances

    shown in this detail if overall dimensions are critical. Complete mill tolerances are given

    in ASTM A6.  For members with both ends finished for contact bearing, a variation of   1/32   in. (0.8

    mm) is permitted.

    At the bottom of the column there is a tolerance of    1

    /4  in. (6 mm) from the center of  any anchor bolt group to the established column line through the group. The center-

    to-center distance between any two bolts within an anchor bolt group cannot vary by

    more than  1/8 in. (3 mm).  The tolerances for columns adjacent to elevator shafts are slightly more restrictive than

    those for other columns. These columns cannot vary more than 1 in. (25 mm) from the

    established column line in the first 20 stories. Above the 20th floor, the displacement

    can be increased   1/32   in. (0.8 mm) for each additional story to a maximum of 2 in.

    (51 mm).  In addition to providing for required steel tolerances, adequate clearances must be

    provided for tolerances of attached materials (such as precast concrete) and for the

    clearances required for working and connecting the various construction materials

    together.

     In general, a column is considered plumb if the deviation of the working line of the

    column from a true plumb line does not exceed 1:500.

    Coordination Required

     The tolerance for setting anchor bolt groups and embedded items is separate from the

    steel erection tolerances and must be taken into account when the total tolerance at any

    given point in the steel frame is determined. However, anchor bolt groups are usually

    set to a tolerance of ±1/4 in. (6 mm).

     Adjustments in the height of prefabricated cladding panels must be provided for due to the accumulated shortening of steel columns under load, which will make the steel

    frame slightly shorter than the unstressed facade.

    3-2   STEEL COLUMN/BEAM CONNECTION

    TOLERANCES

    Description

    As stated in Section 3-4, horizontal alignment of beams is considered acceptable when the

    ends are connected to columns that fall within acceptable tolerances. This section describes

    acceptable variations in both horizontal and vertical placement of beams and tolerances of 

    individual columns between floors.

    Figure 3-2(a) illustrates how the horizontal position of an individual beam work point

    must fall within the allowable column tolerances shown in Fig. 3-1. In addition, the allowable

    vertical tolerance is determined by measuring from the upper column splice line to the

    theoretical beam work point. This distance cannot be greater than  3/16 in. (5 mm) or less than 5/16 in. (8 mm).

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    146   A r c h i t e c t ’s H a n d b o o k o f C o n s t r uc t i o n D e t a i li n g

    Figure 3-2 Steel column/beam connection tolerances 05 05 03.1

    5/16" (8)

    3/16" (5)

       b   u

       i   l    d    i  n   g

       l   i   n  e

    column splice line

       d    i  s    t  a   n   c   e   s

       h   o   w   n   o   n

       d   r  a   w

       i  n  g

      s

    column work point (W.P.)

    theoretical beam work point

    column line

    1" (25) 2" (50)

    Tt

    aT

    W.P.

    W.P.

    out of plumb 1:500 max.

    braced points

    out of straightness L/1000 max.

    L

    (b) allowable tolerances between floors(a) beam-to-column connection tolerances

    As shown in Fig. 3-2(b), the variation in straightness for a straight compression member 

    must be equal to or less than 1/1000 of the axial length between points that are to be laterally

    supported. This is the fabrication tolerance given in AISC 303. For curved members, the

    variation from the theoretical curve must be equal to or less than the variation in sweep that is

    required for an equivalent straight member of the same length as specified in ASTM A6/A6M.

    3-3   STRUCTURAL STEEL COLUMN

    PLAN TOLERANCES

    Description

    Figure 3-3 illustrates some of the allowable variations in cross-sectional size and straightness

    of standard rolled W and HP shapes, commonly used for columns. A  W shape   is a doubly

    symmetric wide-flange shape used as a beam or column whose inside flange surfaces are

    substantially parallel. An   HP shape   is a wide-flange shape generally used as a bearing pile

    whose flanges and webs are of the same nominal thickness and whose depth and width are

    essentially the same. The tolerances shown are those that most affect architectural detailing

    and coordination with other materials.

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    M e t a l D e t a i l s     147

    Figure 3-3 Structural steel column plan tolerances 05 05 04

    (a) size tolerances

    (b) squareness tolerances

    T' = flange tilt

    T = flange tilt

    maximum flanges out of square, T+T' = 1/4" (6) for sections 12" (310) deep and under and T+T' = 5/16" (8) for sections over 12" (310) deep

       C

      =    d   +

       1    /   4    "    (   6    )   m   a  x

     .

    1/2 B ±3/16" (±5)  

    column work point

    B = b +1/4" (6)f

    T' = flange tilt

    f

    d = flange depth as published in   the Manual of Steel Construction 

    C = maximum depth at any cross section

    B = flange width in inches (mm)

    b = flange width as published in   the Manual of Steel Construction -3/16" (5)

    ±5/16 (±8) for secti