Chance Technical Design Manual

WARNING! THE DESIGNER MUST APPLY A FACTOR OF SAFETY TO THE MAXIMUM FREE SPAN WHEN PLANNING THE UNDERPINNING DESIGN SO BEAM FAILURE IS NOT EXPERIENCED.

8” THICK REINFORCED CONCRETE SPREAD FOOTING MAXIMUM FREE SPANS, TABLE 4-7 8” THICK X 16”

BUILDING LINE LOAD (lb/ft) 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000 MAXIMUM FREE SPAN BETWEEN SUPPORTS

SPREAD FOOTING (SEE FIGURE 4-8)

2 - #4 rebars (Gr 60); concrete block or cast stem wall (not dowelled) d = 5” 2 - #4 rebars (Gr 60); 8” x 12” tall cast stem wall (dowelled or monolithic) d = 17” 2 - #4 rebars (Gr 60); 8” x 18” tall cast stem wall (dowelled or monolithic) d = 23” 2 - #4 rebars (Gr 60); 8” x 24” tall cast stem wall (dowelled or monolithic) d = 29” 2 - #4 rebars (Gr 60); 8” x 48” tall cast stem wall (dowelled or monolithic) d = 53”

4’-6” 3’-9” 3’-6”

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7’-7” 6’-6” 5’-10” 5’-4” 4’-11” 4’-7” 4’-4” 4’-2” 3’-11” 3’-9” 3’-8” 3’-5”

– 7’-7” 6’-10” 6’-2” 5’-9” 5’-5” 5’-1” 4’-10” 4’-7” 4’-5” 4’-3” 4’-1”

– 8’-6” 7’-8”

7’

6’-5”

6’

5’-8” 5’-5” 5’-2” 4’-11” 4’-9” 4’-7”

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– 8’-2” 7’-8” 7’-4”

7’

6’-8” 6’-5” 6’-2”

12” THICK REINFORCED CONCRETE SPREAD FOOTING MAXIMUM FREE SPANS, TABLE 4-8 12” THICK X 24”

BUILDING LINE LOAD (lb/ft) 3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000 7,500 8,000 8,500 9,000 MAXIMUM FREE SPAN BETWEEN SUPPORTS

SPREAD FOOTING (SEE FIGURE 4-9)

LOAD DETERMINATION

3 - #5 rebars (Gr 60); 10” x 12” tall cast stem wall (dowelled or monolithic) d = 21” 3 - #5 rebars (Gr 60); 10” x 18” tall cast stem wall (dowelled or monolithic) d = 27” 3 - #5 rebars (Gr 60); 10” x 24” tall cast stem wall (dowelled or monolithic) d = 33”

8’-4” 7’-10” 7’-2”

7’

6’-8” 6’-5” 6’-2” 5’-11” 5’-9” 5’-7” 5’-5” 5’-3”

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– 8’-5”

8’

7’-7” 7’-3”

7’

6’-9” 6’-6” 6’-4” 6’-1” 5’-11”

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8’

7’-9” 7’-5” 7’-2”

7’

6’-9” 6’-7”

MONOLITHIC REINFORCED CONCRETE GRADE BEAM FOOTING MAXIMUM FREE SPANS, TABLE 4-9 TURNED DOWN FOUNDATION CONSTRUCTION (SEE FIGURE 4-10) BUILDING LINE LOAD (lb/ft)

1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 MAXIMUM FREE SPAN BETWEEN SUPPORTS

12” high perimeter beam; 2 - #4 bottom rebars (Gr 60) d = 9”

6’-9” 5’-6” 4’-9” 4’-3” 3’-11” 3’-7”

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20” high perimeter beam; 2 - #5 bottom rebars (Gr 60) d = 17”

– – 8’-2” 7’-5” 6’-8” 6’-2” 5’-9” 5’-6” 5’-2” 4’-11” 4’-9” 4’-6”

24” high perimeter beam; 2 - #5 bottom rebars (Gr 60) d = 21”

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8’-1” 7’-5” 6’-10” 6’-5” 6’-1” 5’-9” 5’-6” 5’-3”

5’

WARNING! THE DESIGNER MUST APPLY A FACTOR OF SAFETY TO THE MAXIMUM FREE SPAN WHEN PLANNING THE UNDERPINNING DESIGN SO BEAM FAILURE IS NOT EXPERIENCED.

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