FIGURE 37. Load group and its resultant.- Calculate the maximum live-load shear in the interior girder
caused by the moving-load group
Place the loads in the position shown in Fig. 386. Do not apply lateral distribution to the
load at the support. Then, FLL = 16 + 17.06(40/54) + 4.26(26/54) = 30.69 kips (136.5 kN). - Verify that the size of the girder is adequate and design
the reinforcement
Thus, WDL = 5.33(96) + 14(33.5/144)(l50) = 1000 Ib/lin ft (14.6 kN/m); FDL = 27 kips
(120.1 kN); MDL = (^1 X 8 )(I)(S^ = 364.5 ft-kips (494 kN-m). By AASHTO, IF = 50/(54 +
125) = 0.28; Ftotal = 27 + 1.28(30.69) = 66.28 kips (294.8 kN); Mtotal = 12(364.5 + 1.28 *
372.8) = 10,100 in-kips (1141 N-m).
In establishing the effective depth of the girder, assume that No. 4 stirrups will be sup-
plied and that the main reinforcement will consist of three rows of No. 11 bars. AASHTO
requires 1 Vfc-in (38.1-mm) insulation for the stirrups and a clear distance of 1 in (25.4 mm)
between rows of bars. However, 2 in (50.8 mm) of insulation will be provided in this
instance, and the center-to-center spacing of rows will be taken as 2.5 times the bar
diameter. Then, d = 5.75 + 33.5 - 2 - 0.5 - 1.375(0.5 + 2.5) = 32.62 in (828.548 mm);
(b) Loading for maximum shearFIGURE 38(a) Loading for maximum moment