
Concept explainers
The force in each of the members of the truss for the given loading.

Answer to Problem 6.38P
The force in member
Explanation of Solution
The free-body diagram of the entire truss is shown in figure 1.
Refer to figure 1 and use symmetry.
Here,
The
Here,
Sum of the moments must be equal to zero.
Here,
Write the equation for
Here,
Put the above equation in equation (I).
Write the expression for the reaction at the point A.
Here,
Substitute
Use symmetry.
Here,
The
Here,
Write the expression for
Put the above equation in equation (II).
Write the expression for the reaction at the point A.
Here,
Substitute
Consider the free body
The net force must be equal to zero.
Here,
Write the expression for
Put the above equation in equation (III).
Here,
Write the expression for
Here,
Write the expression for
Here,
Write the expression for
Here,
Put equations (V), (VI) and (VII) in equation (IV).
Factorize
Equate the coefficient of
Equate the coefficient of
Equate the coefficient of
Put equation (X) in equation (IX).
Substitute
Put the above equation in equation (X).
Consider the free-body joint B. The free-body diagram of joint B is shown in figure 3.
Refer to figure (3) and write the expression for the forces.
Here,
Substitute
Write the expression for
Here,
Write the expression for
Here,
Write the expression for
Here,
Substitute
Write the expression for
Put the above equation in equation (III).
Put equations (XI), (XII), (XIII) , (XIV) and substitute
Equate the coefficient of
Equate the coefficient of
Substitute
Equate the coefficient of
Substitute
Use symmetry.
Here,
Substitute
Consider the free body joint D. The free body diagram is shown in figure 4.
Write the expression for
Put the above equation in equation (III).
Only
Equate the coefficient of
Substitute
Conclusion:
Thus, the force in member
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Chapter 6 Solutions
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