Explanation Method adopted: Method of section. Assumptions: Consider the state of member as tension where the force is pulling the member and as compression where the force is pushing the member. Consider the force indicating the right side as positive and left side as negative in horizontal components of forces. Consider the force indicating upward is taken as positive and downward as negative in vertical components of forces. Consider clockwise moment as negative and anti-clock wise moment as positive wherever applicable. Apply the Equation of equilibrium wherever applicable. Entire truss: Show the free body diagram of entire truss as in Figure 1. Using Figure 1, Reactions: Due to the symmetry of the truss, the external loads are distributed equally to the joints A and D as vertical reactions. Along the vertical direction: Determine the vertical reaction at point A by resolving the vertical component of forces. ∑ F y = 0 A y + D y − 800 − 600 − 800 = 0 (I) Conclusion: Solve Equation (I). A y = D y = 1 , 100 lb Section a-a : Pass a section a-a as shown in Figure 1 and consider right side of the section. Show the free body diagram of right side of the section a-a as in Figure 2. Using Figure 2, Force in the member EF : Moment about point C : Take the moment about joint C , it will eliminate the force in the members CE and CD . ∑ M C = 0 D y ( 10 ) − 800 ( 2.5 ) − F E F sin 30 ° ( 10 ) = 0 (II) Along the vertical direction: Determine the force in the member CE by resolving the vertical component of forces. ∑ F y = 0 F C E sin 60 ° + D y − 800 − F E F sin 30 ° = 0 (III) Conclusion: Substitute 1,100 lb for D y Equation (II)

13th Edition

ISBN: 9780132915540

Author: Russell C. Hibbeler

Publisher: Prentice Hall

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Question

Chapter 6.4, Problem 38P

To determine

The force in members FE and EC of the Fink truss and the state of members are in tension or compression.

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Chapter 6.4, Problem 37P

Chapter 6.4, Problem 39P

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Chapter 6 Solutions

Engineering Mechanics: Statics

Ch. 6.3 - State if the members are in tension or...Ch. 6.3 - State if the members are in tension or...Ch. 6.3 - Prob. 3FP Ch. 6.3 - Determine the greatest load P that can be applied...Ch. 6.3 - Identify the zero-force members in the truss....Ch. 6.3 - State if the members are in tension or...Ch. 6.3 - Prob. 1P Ch. 6.3 - Prob. 2P Ch. 6.3 - Determine the force in each member of the truss,...Ch. 6.3 - Determine the force in each member of the truss,...

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