# Plane Truss

Topics: Force, Newton's laws of motion, Reaction Pages: 11 (1039 words) Published: December 5, 2012
Plane Trusses

1. A pin-jointed truss is loaded as shown in Figure 1. Without obtaining the reactions at the supports, determine the magnitude of the forces in members AB and BC and state whether they are in tension or compression. (Ans: Fbc = - 4.81 kN, Fab = 2.67 kN)

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2. The truss frame hinged at A and supported by roller at G, is subjected to a force of 150 kN at D, and 60 kN at F as shown in Figure 2. a) Draw the free-body diagram of the whole truss frame and find the reaction force at G. ( Rg = 219.02 kN)

b) By using the Method of Sections or otherwise, find the loads in members AB and AF, stating whether they are in tension or compression. (Fab = 225 kN, Faf = - 59.9 kN)

3. A pin jointed truss is hinged at G and supported at A by frictionless rollers on a vertical plane as shown in Figure 3. External forces of 15 kN, 20 kN and 25 kN are applied at joints B, C and H respectively. a) Draw the free-body diagram of the truss.

b) Calculate the reaction at A. (Ra = 35.5 kN)
c) Determine the forces in members EF, FI and HI, indicating whether they are in tension or compression. (Fef = - 11.63 kN, Ffi = - 44.4 kN, Fhi = 3.28 kN) d) Identify the zero-force member (s), if any.

4. A pin-jointed truss is loaded as shown in Figure 4. Without obtaining the reactions at the supports, determine the magnitude of the forces in members BC and CD and state whether they are in tension or compression. (Ans: Fbc = 11.5 kN, Fcd = - 5.77 kN)

5. A lifting crane structure has a truss mechanism as shown in Figure 5. Use Method of Sectioning and without obtaining the reactions at E and G, determine the force in member CE and state whether it is tensile or compressive.

(Ans : Fce = - 15.65 kN)

6. Figure 6 shows a rigid skewed truss with forces acting at B and D. Assuming the joints are pin-jointed,
a) draw the free-body diagram of the truss and determine the reaction at F. b) Without doing any calculation, identify the zero-force member (s). c) Using Method of Sectioning, or any other appropriate method, determine the force in members AB, BF and EF. Indicate whether they are in tension or compression. (Ans: Rf = 300 N, Fab = 150 N, Fbf = - 212.3 N, Fef = - 150 N)

7. The pin-jointed truss shown in Figure 7 is hinged at A and supported by rollers at D. An external force of 10 kN is applied at joint F. Determine : a) the reactions at supports A and D , ( Ra = 7.5 kN, Rd = 2.5 kN) b) the forces in members BC, CF and EF, stating whether they are in tension or compression, and (Fbc = - 3.75 kN, Fcf = 3.54 kN, Fef = 1.25 kN) c) all zero-force members (if any), without calculations.

Figure 7

8. The pin-jointed truss frame as shown in Figure 8, is supported by smooth rollers at B and hinged at A. It is subjected to a 10 kN force at J and a weight of 15 kN at K.
a) Draw the free-body diagram of the whole truss frame and determine the reaction force at B. (Rb = 77.5 kN) (Fbc = - 77.5 kN) b) By using the Method of Joint or otherwise, find the force in member BC. c) By using the Method of Section orotherwise, find the forces in members GI

and HI. (Fgi = 30.5 kN, Fhi = - 29.5 kN)

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9. A pin-jointed truss frame ABCDEF, supported by smooth rollers at C and hinged at D, is...