Calculating Reactions for Three Pinned Beams - Structural Engineering Homework

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SUMMARY

The discussion focuses on calculating the reactions for a system of three pinned beams at points A, B, and C. Participants emphasize the importance of applying the equilibrium equations: the sum of moments at point B must equal zero, along with the sum of horizontal and vertical forces. The correct calculations yield a value for Cx of 61.33, but it is noted that the direction assumed for Cx was incorrect, leading to a negative result. Participants recommend re-evaluating the algebra and using additional equilibrium equations to find the support reactions Ax and Ay, as well as the internal forces Bx and By.

PREREQUISITES
  • Understanding of static equilibrium principles in structural engineering.
  • Familiarity with calculating moments and forces in beam systems.
  • Proficiency in algebraic manipulation for solving equations.
  • Knowledge of support reactions in pinned beam configurations.
NEXT STEPS
  • Review the principles of static equilibrium in structural analysis.
  • Practice solving for reactions in pinned beam systems using equilibrium equations.
  • Learn about the significance of sign conventions in structural calculations.
  • Explore advanced topics such as internal force analysis in beam structures.
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Structural engineering students, civil engineers, and professionals involved in analyzing beam systems and calculating support reactions in structural frameworks.

sukibelle
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Homework Statement



http://tinypic.com/r/2wbxm2s/7
This is a series of beams pinned together at A, B, C
Find reactions at a b c

Homework Equations



Sum of moments at B has to = 0, sum of Fx = 0, sum of Fy = 0

The Attempt at a Solution


Sum of moments about A, anti clockwise +ve
2(-16) + 8Cy -4Cx = 0

considering section BC
sum of momeents about B
4*-25 + 4Cy -8Cx= 0

solving ffor Cx = 61.33


I've been staring at this question all day, it has literally stopped making any sense.
 
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sukibelle said:

Homework Statement



http://tinypic.com/r/2wbxm2s/7
This is a series of beams pinned together at A, B, C
Find reactions at a b c

Homework Equations



Sum of moments at B has to = 0, sum of Fx = 0, sum of Fy = 0

The Attempt at a Solution


Sum of moments about A, anti clockwise +ve
2(-16) + 8Cy -4Cx = 0

considering section BC
sum of momeents about B
4*-25 + 4Cy -8Cx= 0
These equations are both correct
solving ffor Cx = 61.33
You didn't solve the 2 equations correctly.
I've been staring at this question all day, it has literally stopped making any sense.

Redo the algebra. Cx will come out negative , meaning you assumed the wrong direction for Cx. After finding Cy from these equations, use the other relevant equilibrium equations to solve for the support reactions Ax and Ay, and the internal forces Bx and By at B.
 

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