Truss Homework: Solving for Joint Forces using Method of Joints

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SUMMARY

The discussion focuses on solving for joint forces in a truss using the Method of Joints. Participants emphasize the importance of starting at joints with only two unknown member forces to simplify calculations. The angles for the triangles formed at the joints are established as A = B = 53.13 degrees and C = 73.74 degrees, derived from the cosine law and the 180-degree rule. A critical recommendation is to determine support reactions first before selecting the appropriate joint to analyze.

PREREQUISITES
  • Understanding of the Method of Joints in truss analysis
  • Familiarity with the cosine law for calculating angles
  • Knowledge of static equilibrium principles in mechanics
  • Ability to calculate support reactions in truss structures
NEXT STEPS
  • Study the Method of Joints in-depth for truss analysis
  • Learn how to apply the cosine law in structural engineering problems
  • Research static equilibrium and its applications in mechanics
  • Explore techniques for calculating support reactions in various truss configurations
USEFUL FOR

Engineering students, structural analysts, and professionals involved in truss design and analysis will benefit from this discussion.

bnosam
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Homework Statement


http://oi59.tinypic.com/2h65cm1.jpg[/B]

Homework Equations

The Attempt at a Solution


[/B]
All triangles: angles A = B = 53.13 degrees, angle C = 73.74 degrees

from cosine law and the 180 degree ruleBut it looks like all of the joints in the bridge have more than 2 forces? Which joint should I start at?

I was going to start at B but it looks like i have the 3000 lb force, then BC, BE and BA forces which would be too many.
 
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bnosam said:

Homework Statement


http://oi59.tinypic.com/2h65cm1.jpg[/B]

Homework Equations

The Attempt at a Solution


[/B]
All triangles: angles A = B = 53.13 degrees, angle C = 73.74 degrees

from cosine law and the 180 degree ruleBut it looks like all of the joints in the bridge have more than 2 forces? Which joint should I start at?

I was going to start at B but it looks like i have the 3000 lb force, then BC, BE and BA forces which would be too many.
Always determine the support reactions first. Then start at a joint or joints where there are just 2 unknown member forces, then proceed to the others.
 

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