[Statics] Determining the normal force at an internal point of a member

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SUMMARY

The discussion focuses on determining the normal force at an internal point E of a member in a frame structure. The correct approach involves dividing the frame into members AB and CB, calculating the reaction forces at point B, and using a free body diagram for member EB. An alternative method that treats the two members as a system and sets the sum of moments about point A was attempted but yielded incorrect results due to a numerical error. The correct methodology ensures accurate calculations of internal forces in structural analysis.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Familiarity with free body diagrams
  • Knowledge of reaction forces in frame structures
  • Basic skills in solving systems of equations
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  • Study advanced techniques for analyzing internal forces in frame structures
  • Learn about the method of sections in structural analysis
  • Explore the use of software tools for structural analysis, such as SAP2000
  • Investigate common errors in calculating reaction forces and internal loads
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Structural engineers, civil engineering students, and professionals involved in analyzing frame structures will benefit from this discussion.

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TL;DR
A statics question regarding a two-member frame.
For this problem (see image), I get the correct answer for the normal force at point E if I:
1) divide the frame into members AB and CB,
2) solve for the x and y components of the reaction force at point B,
3) make a free body diagram with the cut at point E forming member EB and setting the sum of the x-components of the forces to 0 and solving for the normal force.

BUT

If I try to solve it by treating the two members as a system (and, thus, discount the reaction force at B), setting the sum of the moments about point A to 0 and then solving that for the x-component of the reaction force at point C which would then equal the the negative of the normal force at point E, I don't get the same answer. Why is that?
 

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I figured it out. Used a wrong number for the second method causing the answer to differ. Thank you nonetheless.
 
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