- Design the stem
At the base of the stem, y = 16.5 ft (5.03 m) and d = 18 - 3.5 = 14.5 in (368.30 mm);
TEF = 7030 Ib (31,269.4 N); MEF= 538,000 in-lb (60,783.24 N-m). The allowable shear at
a distance d above the base is Fallow = vbd = 60(12)(14.5) = 10,440 Ib (46,437.1 N). This
is acceptable. Also, Mb = 223(12)(14.5)^2 = 563,000 in-lb (63,607.74 N-m); therefore, the
steel is stressed to capacity, and As = 538,000/[20,000(0.874)(14.5)] - 2.12 in^2 (13.678
cm^2 ). Use no. 9 bars 51 X 2 in (139.70 mm) on centers. Thus, A 8 = 2.18 in^2 (14.065 cm^2 );
So = 7.7 in (195.58/mm); u = 7030/[7.7(0.874)(14.5)] = 72 lb/in^2 (496.5 kPa); wallow =
235 lb/in^2 (1620.3 kPa). This is acceptable.
Alternate bars will be discontinued at the point where they become superfluous. As the
FIGURE 29
(c)Soil pressure with
surcharge to G
(d) Soil pressure with
surcharge to H
(a) Retaining wall
(b) Active earth
pressure
