Скачать или смотреть Determine the force in members KJ, KD, and CD of the Pratt truss. State if the members

Determine the force in members KJ, KD, and CD of the Pratt truss. State if the members are in tension or compression.
























Answer








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Step 1: Draw and Label the Pratt Truss Diagram
Identify joints K, J, D, and C.
Label members KJ, KD, and CD.
Include all external loads and support reactions.

Step 2: Determine Support Reactions
Apply equilibrium equations ΣFx = 0, ΣFy = 0, and ΣM = 0 to solve for the reaction forces at the supports.
Ensure to solve for vertical and horizontal reactions, if not already provided.

Step 3: Start with Joint J (or an adjacent joint with known reactions)
Apply the method of joints by selecting a joint where two unknown member forces meet.
At joint J, solve for the force in member KJ:
• Write the equilibrium equations: ΣFx = 0 and ΣFy = 0.
• Solve the equations to find the force in member KJ.
*Interpretation:*
If the force in KJ is positive, it is in tension (pulling away from the joint).
If the force is negative, it is in compression (pushing toward the joint).

Step 4: Move to Joint D (or another joint with known forces)
Analyze joint D, where members KD and CD meet, to solve for their forces.
Write the equilibrium equations: ΣFx = 0 and ΣFy = 0 for joint D.
Solve for the force in member KD and the force in member CD.
*Interpretation:*
If the force in KD is positive, it is in tension; negative indicates compression.
Similarly, a positive force in CD indicates tension, and negative indicates compression.

Step 5: Summarize the Results
List the force values found for members KJ, KD, and CD.
Clearly state whether each member is in tension or compression.
Tension: Force pulling away from the joint.
Compression: Force pushing toward the joint.

Note:
The precise calculations depend on the geometry of the truss (angles, lengths) and the load distribution.
For each joint, use algebraic signs (positive for tension, negative for compression) to indicate the force direction.
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