# Method of Joints to Solve a Truss Problem

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This Demonstration solves a truss using the method of joints, which involves doing force balances around one joint at a time.

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Contributed by: Rachael L. Baumann (September 2017)

Additional contributions by: John L. Falconer

(University of Colorado Boulder, Department of Chemical and Biological Engineering)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

First, calculate the reaction forces by doing a moment balance around joint and force balances in the and directions:

,

,

,

where and are the reaction forces at joint in the and directions, is the reaction force at joint , is the width of the members and is the point load force at joint .

Next, do force balances at the joints. The order of the calculations shown is the order that the joints are solved in. Calculations are done assuming we know which members are under tension and which are under compression. View the labeled truss in Figure 1 below.

,

.

,

.

,

.

.

Figure 1

References

[1] R. C. Hibbeler, *Engineering Mechanics: Statics*, 12th ed., Upper Saddle River, NJ: Prentice Hall, 2010.

[2] D. Morrell. *Truss Example-Method of Joints (Edited)* [Video]. (Jun 6, 2012) www.youtube.com/watch?v=56eTM36Z9-A.

## Permanent Citation