Handbook of Civil Engineering Calculations

5. Place the system in the position thus established,
   and compute Vde
   Thus, RL = 50(100 + 6 - 13.8)7200 = 23.1 kips (102.75 kN). The load at panel point d is
   Pd= 5(6)725 1.2 kips (5.34 kN); Vde = 23.1 - 1.2 = 21.9 kips (97.41 kN).


6. Assume left-to-right locomotion; proceed as in step 3
   Consider that load 4 is within panel de and the remaining loads are to the right of this pan-
   el. Proceeding as in step 3, we find dVJdx = 15(7/200) + 35( - 1/200) > O.
   So, as the system moves from left to right, Vde is maximum at the instant that load 4 is
   ate.


7. Place the system in the position thus established, and
   compute Vde
   Thus Vde = RL = [50(100 - 8.2)1/200 = 23.0 kips (102.30 kN); /. Frfemax = 23.0 kips
   (102.3OkN).


8. Compute the maximum tensile force in De
   Using the same relation as in step 3 of the previous calculation procedure, we find esc 0 =
   [(25^2 + 302 )/30^2 ]^05 = 1.30; then De = 23.0(1.30) = 29.9-kip (133.00-kN) tension.

INFLUENCE LINE FOR BENDING MOMENT

IN BRIDGE TRUSS

The Warren truss in Fig. 5Oa supports a bridge at its top chord. Draw the influence line
for the bending moment at b caused by a moving load traversing the bridge floor.

panels

panels

(a) Warren truss

FIGURE 50