Chance Technical Design Manual

BASEMENT WALL

H = Height of backfill n = Tieback location from top of wall = 0.2 to 0.6 FS = Factor of Safety = 1.5 < FS < 2.5 T = Tension load (lb/ft of wall)/cos( φ ). Assumes tieback provides 80% of lateral support. T U = 18(H 2 )FS/cos( φ ) (no water pressure present) T U = 45(H 2 )FS/cos( φ ) (water pressure present)

nH

φ

T or T U

H

NOTE: Top of wall is assumed to be restrained in the lateral direction

ESTIMATED TIEBACK FORCE REQUIRED FOR BASEMENT APPLICATIONS FIGURE 4-4

RETAINING WALL

LOAD DETERMINATION

H = Height of backfill (walls 15 ft or less) n = Tieback location from top of wall = 0.25 to 0.40 FS = Factor of Safety = 1.5 < FS < 2.5 T = Tension load (lb/ft of wall)/cos( φ ) T U = 25(H 2 )FS/cos( φ ) NOTE: Top of wall is assumed free to translate

nH

φ

T or T U

H

ESTIMATED TIEBACK FORCE REQUIRED FOR RETAINING WALLS 15 FEET HIGH OR LESS FIGURE 4-5

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