EXTERIOR COLUMN CALCULATIONS

• Columns are placed at the corners (corner columns) of a building and at the points where the modular grid intersects the long outer walls (exterior wall columns). Additional columns may be placed in the center of the end walls (end wall columns) and along a central modular grid line for the length of the building (interior columns).
• Columns are designated by a symbol, a number and a second number: Ø4 x 10 - where the Ø4 is the DIAMETER of the column in inches and the 10 is for the LENGTH of the column.
• The total roof load (live and dead) in pounds per square foot, the weight of the truss per lineal foot, the number of truss between the columns, the spacing between the trusses, the length of the trusses, the length of the beam, the weight of the beam in pounds per lineal foot, the height of the column and spacing of the columns in feet and inches must be know to find the size of a column from standardized tables.
• A safety factor of 5 to 15 percent should be considered at the end of each calculation but should avoid duplicaton when calculating beams and columns.

Carefully follow these steps for finding the correct EXTERIOR WALL COLUMN:

Step 1 - Enter the following data from your "Structural Layout" and "Truss & Beam Calculations Sheets":

TOTAL ROOF LOAD = ___________ lbs./sq.ft.

SPAN (Length of truss) _______ feet

SPACING (between trusses) _______ feet

LENGTH of Beam (between Columns) ______ feet

WEIGHT of End Truss _________ lbs./lin.ft.

WEIGHT of Interior Truss _________ lbs./lin.ft.

No. of Trusses on EXTERIOR BEAM ______ (Do not count trusses sitting on columns)

WEIGHT of Exterior Beam ______ lbs./lin.ft.

COLUMN LENGTH (Height) _______ feet

SPACING (between columns) ______ feet

Step 2 - Find the amount of roof supported by a EXTERIOR WALL COLUMN:

( Half of the length of the Beam to the LEFT of the column + Half of the length of the Beam to the RIGHT of the column) x Half of the length of the Truss = AREA of Roof supported by the COLUMN

Step 3 - Find the weight of this ROOF AREA :

Total Roof Load in lbs./sq.ft. x Area of Roof in sq.ft. = Weight of Roof in lbs.

Step 4 - Find the weight of the TRUSSES:

(Half of the length of an Int. Truss x Weight of Truss x the Number of Trusses) = Total Weight of Trusses in lbs.

Step 5 - Find the weight of an EXTERIOR BEAM:

(Half the length of an Ext. Beam to the LEFT of the column x "Weight of Beam" ) + (Half the length of an Ext. Beam to the RIGHT of the column x "Weight of Beam" in lbs/lin.ft.) = TOTAL Weight of Beams in lbs.

Step 6 - Find the total weight on a EXTERIOR WALL COLUMN:

Add "Weight of Roof" + "Weight of Trusses" + "Weight of Beams" = TOTAL WEIGHT on Column in lbs.

Step 7 - Consult the "Structural Steel Tables" to find the correct size:

Convert total weight to KIPS (1KIP=1000 lbs.) then start with the "Height of the Beam" and look down the table for the "Load" that is equal to or slightly larger than the TOTAL WEIGHT.

Step 8 - Make note of the following:

Column Designation __________________

Column Size _______ inches

Weight or thickness of Column ________

Max. Allow. Wt. _______________ lbs.

Step 9 - Assign a CODE LETTER to this EXTERIOR COLUMN: __________ Examples: AAA or C1 or CC