The cast iron beam shown is to be made of ASTM 25. The resultant loads F = 3171 lb and F = 2(F1) lb are as given. However, resultant load F is spread at a span of 18 inches as shown, while F2 can be assumed as a concentrated load due to a relatively narrow contact. The loads are gradually applied and repeated. Let H = 8a and B = 5a. What is the maximum bending moment of the beam in lb-in? Express your answer using 4 significant figures. F1 18" R1 36" F2 12 a H a R B