Determining the forces in a framework

In summary, the conversation discusses a framework with three unknown members, making it statically indeterminate and difficult to solve using equations of statics alone. To solve for the member forces, a different approach, such as using Castigliano's theorems, is recommended.
  • #1
question dude
80
0
The framework is attached below. I've tried going to each joint and resolving the forces vertically and horizontally. I've got to joint B and I'm stuck, because I have three unknown members there. And its the same if I go to joint J.

what do I do?
 

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  • #2
I don't see a joint J.

Can you set up 2 equations at 4 joints and solve for 8 unknowns?
 
  • #3
You are stuck because the frame is statically indeterminate. This means that the equations of statics alone are insufficent to solve for the member forces. If you want to proceed you have to introduce another equation related to the member properties AE. There are a number of different approaches to this, including use of Castigliano's theorems. That is what I suggest you look up.
 

1. What is a framework?

A framework is a structure composed of interconnected parts that work together to provide stability and support. In the context of determining forces, a framework refers to a physical or mathematical model used to analyze the external and internal forces acting on a structure.

2. Why is it important to determine the forces in a framework?

Determining the forces in a framework is crucial for understanding the structural integrity and stability of a system. It allows engineers and scientists to identify potential weak points or areas of stress in a structure, and make necessary adjustments to ensure its safety and functionality.

3. What methods are used to determine forces in a framework?

There are several methods used to determine forces in a framework, including static analysis, dynamic analysis, and computer simulations. These methods involve using mathematical equations and principles of mechanics to calculate the forces acting on each member of the framework.

4. How do external forces affect a framework?

External forces, such as wind, gravity, and applied loads, can significantly impact the stability and strength of a framework. These forces can cause stress, deformation, or failure in the structure if they exceed its capacity to withstand them. Therefore, it is essential to determine and account for these forces when designing and analyzing a framework.

5. What are the assumptions made when determining forces in a framework?

When determining forces in a framework, several assumptions are typically made to simplify the analysis process. These may include assuming the framework is rigid, all members are perfectly connected, and the load distribution is uniform. These assumptions may not always hold true in real-life scenarios, but they provide a good approximation for analyzing the forces in a framework.

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