Page 339 - Forensic Structural Engineering Handbook

TEMPORARY STRUCTURES IN CONSTRUCTION 10.27

4 spaces @ 7'-6" C-C 10 spaces @ 8'-0" C-C
30'-0" 80'-0" Varies
14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
29
N
W14 145 (typ) 30
24'-0" 3 spaces @ 8'-0" C-C
31
HP14 89 (typ)
(35° from horizontal) 32
W14 90
33
HP10 42* (typ)
34
HP14 102
W14 109 35
W14 99
36
W14 145
37
77'-0"
38 11 spaces @ 7'-0" C-C
W27 146
39
40
W14 145
41
42
W14 90 43
44

HP14 89 45
40'-0" 5 spaces @ 8'-0" C-C
HP14 117 HP14 89
(39 ° from horizontal) 46
W14 145 (typ)
47
48
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
4 spaces @ 7'-6" C-C 10 spaces @ 8'-0" C-C Varies
30'-0" 80'-0"
(e)
FIGURE 10.3 Washington excavation. (Continued) (e) Bottom tier of internal bracing. (From
OSHA Investigation of November 19, 1990 Excavation Collapse at 14th & H Streets, N.W.,
Washington, D.C. report, May 1991.)

between the soldier beam and wale, to accommodate the thicknesses of the perimeter wall of
the permanent basement between the lagging and the wales, and to provide for removing the
wale and cutting off the protruding outlookers from inside the finished basement wall when the
concrete wall gained adequate strength. The outlookers were welded to the inside face of the
soldier beams and the outside face of the wales.
The initial collapse was followed 17 hours later by a second additional collapse of a por-
tion adjacent to the first one, resulting in a great deal of damage in and around the excavation.
OSHA investigators concluded that the collapse of the excavation occurred due to
the failure of certain structural members of the internal support system along the north