Architectural Drawing
Structural Calculations
Beams and Girders
Beams or girders support floor joists over long spans.
Beams or girders May be wood or metal.
Wood beams may be built-up or solid.
Steel beams may be S-beams or W-beams.
Size based on weight of the structure and the span.
Structure Loads
Dead load is the weight of the structure itself:
Roofing, siding, joist, etc.
Live load is the fixed or moving weights:
Furniture, appliances, occupants, snow on the roof, etc.
Structural Calculations
Weight Supported by Beam
Typical Load
Distribution in a
Structure
Structural Calculations
Typical Load Distribution in a Structure
Structural Calculations
Building Loads
Make a sketch of the load distribution.
Make a listing of the building loads using the following format:
Area
Construction
Live Load
(lbs/sq ft)
30
Dead Load
(lbs/sq ft)
8
Total Load
(lbs/sq ft)
38
ROOF
BUILT-UP
ATTIC
WITH STORAGE
20
10
30
FLOOR
FIRST FLOOR
40
10
50
PARTITIONS
PARTITIONS FIRST FLOOR
0
10
10
Total Building Load
128 LBS/SQ FT
Structural Calculations
30'-0"
15'-0"
7'-6"
15'-0"
BEAM SUPPORT AREA
NO COLUMNS
7'-6"
15'-0"
Beam Support Area with no columns
60'-0" (SPAN)
Structural Calculations
30'-0"
15'-0"
7'-6"
15'-0"
BEAM SUPPORT AREA
ONE COLUMN
7'-6"
15'-0"
Beam Support Area with one column
30'-0" (SPAN)
60'-0"
Structural Calculations
30'-0"
15'-0"
7'-6"
15'-0"
BEAM SUPPORT AREA
TWO COLUMNS
7'-6"
15'-0"
Beam Support Area with two columns
20'-0" (SPAN)
60'-0"
Structural Calculations
Beam Calculations
Make a listing of the loads acting on the beam using the following format:
ROOF
Area
Building Load (lbs/sq ft)
0
ATTIC
30
FIRST FLOOR
50
PARTITIONS
10
Total Load acting on the beam
90 LBS/SQ FT
Make a series of trials using various numbers of columns and record the date using the following format:
Trial
Number of
Columns
Span (ft)
Support
Width (ft)
Load
(lbs/sq ft)
15
Support
Area
(sq ft)
900
90
Support
Load
(Kips)
81
1
0
60
2
1
3
4
30
15
450
90
40.5
W12 x 53
2
20
15
300
90
27
W8 x 31
3
15
15
225
90
20.25
W8 x 18
Mark final selection of beam size and number of columns.
Beam Size
NA
Structural Calculations
W-beam span and load table.
(American Institute of Steel Construction)
Structural Calculations
W-beam span and load table.
(American Institute of Steel Construction)
Structural Calculations
30'-0"
15'-0"
7'-6"
15'-0"
COLUMN SUPPORT AREA
ONE COLUMN
7'-6"
15'-0"
Column Support Area with one column
30'-0" (SPAN)
60'-0"
Structural Calculations
30'-0"
15'-0"
7'-6"
15'-0"
COLUMN SUPPORT AREA
TWO COLUMNS
7'-6"
15'-0"
Column Support Area with two columns
20'-0" (SPAN)
60'-0"
Structural Calculations
Column Calculations
Make a series of trials using various numbers of columns and record the date using the following format:
Number of
Columns
Span (ft)
Support
Width (ft)
Total Load
(lbs/sq ft)
15
Support
Area
(sq ft)
450
1
30
2
3
Column
Height (ft)
Column
Size
90
Support
Load
(Kips)
40.50
13
5
20
15
15
15
300
90
27.00
13
4
225
90
20.25
13
3.5
Structural Calculations
Beam Support Area
Structural Calculations
Column Support Area
Structural Calculations
Ceiling Joists
Structural Calculations
Procedure for Using Span Data Charts
•
•
•
•
•
Select species of wood to be used.
Select appropriate live load.
Determine lumber grade to be used.
Scan the lumber grade row and note the maximum spans.
Select the joist size and spacing that will support the desired
live load (16" OC spacing is typical).
Structural Calculations
Structural Calculations
Structural Calculations
Structural Calculations
Joist and Rafter selection
Indicate the selection of joist and rafter sizes and spacing by listing the data using the following format (be sure to show all possible combinations):
Live Load
Area
Floor Joist
40
Species
Southern Pine
Floor Joist
10
Grade
#2
Span (ft)
15
Size
2 x 10
Spacing
16
Southern Pine
#1
15
2 x 10
16
Floor Joist
Southern Pine
SS
15
2 x 10
16
Floor Joist
Southern Pine
#2
15
2 x 12
16
Floor Joist
Southern Pine
#1
15
2 x 12
16
10
Grade
#2
Span (ft)
15
Size
2 x 10
Spacing
16
20
Dead Load
Live Load
Area
Ceiling Joist
Species
Southern Pine
Ceiling Joist
Southern Pine
#2
15
2 x 10
16
Ceiling Joist
Southern Pine
#1
15
2 x 10
16
Ceiling Joist
Southern Pine
SS
15
2 x 10
16
Ceiling Joist
Southern Pine
#2
15
2 x 10
16
30
Dead Load
Live Load
Area
Roof Rafter
Species
Southern Pine
Dead Load
8
Grade
#2
16
Size
2 x 10
16
Roof Rafter
Southern Pine
#1
16
2 x 10
16
Roof Rafter
Southern Pine
SS
16
2 x 10
16
Roof Rafter
Southern Pine
#3
16
2 x 12
16
Roof Rafter
Southern Pine
#2
16
2 x 12
16
Span (ft)
Mark the final selection of materials. Use the same species and grade for the selected structural components.
Spacing
Structural Calculations
Footing Calculations
Make a listing of the loads acting on the footings using the following format:
Type of Ground
Area
Safe Ground Loading
(lbs/sq ft)
Length (ft)
Building
Load
(lbs/sq ft)
Total Load
(lbs/ft)
Roof
Attic
Floor
Partitions
Area
Wall Width
(ft)
Length (ft)
Building
Load
(lbs/cu ft)
Total Load
(lbs/ft)
First floor wall
Basement wall
Total load acting on the footing
Safe ground loading for soil type
Minimum footing width (ft)