three moving loads

Problem 457
A truck and trailer combination crossing a 12-m span has axle loads of 10, 20, and 30 kN separated respectively by distances of 3 and 5 m. Compute the maximum moment and maximum shear developed in the span.
 

Problem 456
Three wheel loads roll as a unit across a 44-ft span. The loads are P₁ = 4000 lb and P₂ = 8000 lb separated by 9 ft, and P₃ = 6000 lb at 18 ft from P₂. Determine the maximum moment and maximum shear in the simply supported span.