3. Design of Columns by spColumn
This section includes the design of interior, edge, and corner columns using spColumn software. The preliminary dimensions for these columns were calculated previously in section one. The reduction of live load per ASCE 7-10 will be ignored in this example. However, the detailed procedure to calculate the reduced live loads is explained in the “One-Way Wide Module Joist Concrete Floor Design” example.
3.1. Determination of Factored Loads
Assume 5 story building
Interior Column (Column #1):
Tributary area for interior column for live load, superimposed dead load, and self-weight of the slab is
ATributary = (30 × 30) = 900 ft2
Tributary area for interior column for self-weight of additional slab thickness due to the presence of the drop panel is
ATributary = (10 × 10) = 100 ft2
• Pu | = | 5 × qu × ATributary = 5 × (0.270 × 900 + 0.064 × 100) = 1246.88 kips |
• Mu,x | = | 40.59 ft-kips (see the previous Table) |
• Mu,y | = | 40.59 ft-kips (see the previous Table) |
Edge (Exterior) Column (Column #2):
Tributary area for edge column for live load, superimposed dead load, and self-weight of the slab is
Tributary area for edge column for self-weight of additional slab thickness due to the presence of the drop panel is
• Pu | = | 5 × qu × ATributary = 5 × (0.270 × 475.00 + 0.064 × 58.33) = 659.85 kips |
• Mu,x | = | 157.15 ft-kips (see the previous Table) |
• Mu,y | = | 22.09 ft-kips (see the previous Table) |
Edge (Exterior) Column (Column #3):
Tributary area for edge column for live load, superimposed dead load, and self-weight of the slab is
Tributary area for edge column for self-weight of additional slab thickness due to the presence of the drop panel is
• Pu | = | 5 × qu × ATributary = 5 × (0.270 × 475.00 + 0.064 × 58.33) = 659.85 kips |
• Mu,x | = | 22.09 ft-kips (see the previous Table) |
• Mu,y | = | 157.15 ft-kips (see the previous Table) |
Corner Column (Column #4):
Tributary area for corner column for live load, superimposed dead load, and self-weight of the slab is
Tributary area for corner column for self-weight of additional slab thickness due to the presence of the drop panel is
• Pu | = | 5 × qu × ATributary = 5 × (0.270 × 250.69 + 0.064 × 34.03) = 349.28 kips |
• Mu,x | = | 97.19 ft-kips (see the previous Table) |
• Mu,y | = | 97.19 ft-kips (see the previous Table) |
The factored loads are then input into spColumn to construct the axial load – moment interaction diagram.
3.2. Moment Interaction Diagram
Interior Column (Column #1):
Edge Column (Column #2):
Edge Column (Column #3):
Corner Column (Column #4):
