INTERIOR 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 INTERIOR COLUMN:

Step 1 - Enter the following data from your "Structural Layout" or "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 A _________ lbs./lin.ft.

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

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

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

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

WEIGHT of Interior Beam A ______ (feet)

WEIGHT of Interior Beam B ______ (feet)

COLUMN LENGTH (Height) ________feet

Step 2 - Find the amount of roof supported by an INTERIOR Column:

(Half of the LENGTH of the Beam to one side of the Column plus Half of the LENGTH of the Beam to other side of the Column) x (Half of the LENGTH of the Truss to one side of the CLOUMN plus Half of the LENGTH of the TRUSS to other side of the COLUMN) = AREA of Roof supported by the COLUMN in sq.ft.

Step 3 - Find the weight of this ROOF AREA :

Total Roof Load x Area of Roof = Weight of Roof in lbs.

Step 4 - Find the weight of the TRUSSES:

(Half of the LENGTH of an INTERIOR Truss A to one side of the COLUMN x Weight of Truss lbs/lin.ft.) + (Half of the LENGTH of an Interior Truss B to the other side of the COLUMN x Weight of Truss lbs./lin.ft.)] x ( the Number of Trusses) = Total Weight of Trusses inlbs.

Step 5 - Find the total weight of an INTERIOR BEAM:

(Half of the LENGTH of an interior Beam A to one side of the COLUMN plus Half of the LENGTH of an interior Beam B to the other side of the COLUMN) x "Weight of Beam" = TOTAL Weight of Beams in lbs.

Step 6 - Find the total weigth on an INTERIOR COLUMN:

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

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 COLUMN" 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 INTERIOR COLUMN: __________ Examples: AAA or C1 or CC