A snow load transfers the forces shown to the upper joints of the Pratt and Howe roof lattices shown below. Ignoring the horizontal responses on the supports (\(A x=Ex=0 \)) a) Determine the forces in all members using the joint method. Pratt Roof Truss System: AA R Rodi Pull Push x=2 y=3,4 height (m) Z=4,2 BB X H y 1 2 3 CC c G 4 y BB 5 D F X 6 Pratt Roof Truss System SOLUTION: AA 4 A 4-digit number must be written after the comma. For example 14.7845. Forces (kN) AA=4,2 BB=4,2 CC=5,7 WIDTH (m)

Method of Sections. By method of sections, determine the bar force in members bd, ef, de, ce, of the truss shown in Figure 2 Figure 2 a 30 kN a 25 KN 60 KN a a (D 25 KN a 40 KN a a 13

Objective: Practice analyzing indeterminate truss systems with bar redundancies. The scissor truss below supports a roof with the factored loads shown. All members are steel shapes with E - 29000 ksi. Complete the following prompts considering this truss. a. Show mathematically that the truss is statically indeterminate. b. If all members have equal areas of A = 8 in.2, determine all member forces and report your results in a table. You should use the principle of virtual work with Member BE as your redundant member. c. Repeat part (b) but modify Member BE only such that its area is A = 2 in.2. Describe the effect of this modification on the member forces in the truss compared to those found in part (b) (both the total member forces in the indeterminate system and those in the statically determinate subsystem). 12' A 14¹. 30 k B '16' 60 k C 16¹- 30 k D 14' E Note: You do not need to show repeated calculations in part (c). Attach any Excel sheets used to facilitate your calculations.

The truss structure shown in Figure 3.31 is to be analyzed to find the member forces. Choosing the following determinate base structure we calculate the member forces for load cases 0, 1, and 2. (two redundants cb and cf)