The roof truss of a warehouse can be represented by the planar pin-jointed truss in Figure...

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The roof truss of a warehouse can be represented by the planar pin-jointed truss in Figure 2. Wind load can be represented by a horizontal point load at E, and the load from a crane supported on the truss by a vertical load, initially at J. (a) A vertical load of 30 kN is applied at J and a horizontal load of 20 kN is applied at E, as shown in Figure 2. i) Calculate the support reactions at K and F. ii) Find the force in bar CG and state whether it is in tension or compression. (b) The 30 kN vertical load can now move between nodes J, H and G. The 20 kN load remains in the same location. Bar CG is made of timber with an elastic modulus of 12 GPa, and has a cross sectional area of 3000 mm². i) Calculate the force in CG for each location of the vertical 30 kN load. ii) What is the change of length of CG as the vertical load is moved from J to G? A 2m 2m K B J H C D ✓ 30KN Figure 2: Planar truss for analysis. E F 77777 20KN The roof truss of a warehouse can be represented by the planar pin-jointed truss in Figure 2. Wind load can be represented by a horizontal point load at E, and the load from a crane supported on the truss by a vertical load, initially at J. (a) A vertical load of 30 kN is applied at J and a horizontal load of 20 kN is applied at E, as shown in Figure 2. i) Calculate the support reactions at K and F. ii) Find the force in bar CG and state whether it is in tension or compression. (b) The 30 kN vertical load can now move between nodes J, H and G. The 20 kN load remains in the same location. Bar CG is made of timber with an elastic modulus of 12 GPa, and has a cross sectional area of 3000 mm². i) Calculate the force in CG for each location of the vertical 30 kN load. ii) What is the change of length of CG as the vertical load is moved from J to G? A 2m 2m K B J H C D ✓ 30KN Figure 2: Planar truss for analysis. E F 77777 20KN

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a i Support reactions At K RK 20kN horizontal force balance ... View the full answer