Answer Happy

The structure shown below is a simplified tower crane. It carries a shipping crate suspended from B that has a weight of 149 kN The main jib DCB in green) has a weight of 21 kN concentrated in the center of the beam. This is pinned to the main body at D and is supported by a cable that is routed through pulleys at F and G and is attached to a concrete counterweight J. The main body AEFG (in yellow) is fixed to the ground at A. F h3 ө7 E h2 С B J l1 22 13 hi
hi A Various geometry: h1 = 26 m h2 = 4 m hg = 5.4 m 11 = 12.8 m 12 = 16.5 m 13 = 3.8 m 0= 61.9 degrees Assumptions: . The main body AEFG can be considered massless. • The cable CFGJ is massless. • The pulleys at F and G can be considered massless, frictionless, and of negligible diameter. • All bodies are considered rigid. i. Determine the weight of counterweight J in order for the main jib DCB to be horizontal. ii. Determine the magnitude of the cand y components of force at pin D. iii. Determine the reactions at fixed support A.