Statics problem(simple beam/three supports/one moment)

In summary, the conversation discusses the problem of solving for the reaction forces Ay, By, and Cy, with the presence of a clockwise couple at point A. The equations of static equilibrium are used to try and solve for the reactions, but due to the beam being statically indeterminate, a third equation is needed to solve for the unknown reactions. This can be found by using a different method that does not involve the sum of forces or moments.
  • #1
Halest0rm3
1
0
6k8aLNb.png

Homework Statement


I have to solve for Ay, By, and Cy reaction forces. The constant C is a couple acting at A in a clockwise direction

Homework Equations


Sum of all forces = 0
Sum of Moments about any point = 0

The Attempt at a Solution


I solved for all four reaction equations(one force sum and three moment equations at a,b, and c) These are the four equations I calculated:

Ay + By + Cy = 0
36(By) + 3(36)(Cy) = C
2(36)(Cy) - 36(Ay) = C
-3(36)(Ay) -2(36)(By) = C

But no matter how I try to solve the system of equations I always get 0 = 0 or a singular matrix. I don't know if the problem is that I messed up with one of the moment equations or if there is something else I need to do. Any help would be very much appreciated, thanks!
 
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  • #2
Halest0rm3 said:
6k8aLNb.png

Homework Statement


I have to solve for Ay, By, and Cy reaction forces. The constant C is a couple acting at A in a clockwise direction

Homework Equations


Sum of all forces = 0
Sum of Moments about any point = 0

The Attempt at a Solution


I solved for all four reaction equations(one force sum and three moment equations at a,b, and c) These are the four equations I calculated:

Ay + By + Cy = 0
36(By) + 3(36)(Cy) = C
2(36)(Cy) - 36(Ay) = C
-3(36)(Ay) -2(36)(By) = C

But no matter how I try to solve the system of equations I always get 0 = 0 or a singular matrix. I don't know if the problem is that I messed up with one of the moment equations or if there is something else I need to do. Any help would be very much appreciated, thanks!
This beam is statically indeterminate. You can write only two equations of static equilibrium, but you have 3 unknown reactions to solve for.

You'll have to find a third equation to use which doesn't involve the sum of the forces or the sum of the moments.

https://en.wikipedia.org/wiki/Statically_indeterminate
 

1. What is a simple beam?

A simple beam is a type of structural element that is used to support loads and transfer them to its supports. It is a long, straight member that is supported at both ends and is free to rotate at those supports.

2. How many supports are required for a simple beam?

A simple beam needs at least two supports, one at each end, to be stable. However, for longer beams or heavier loads, additional supports may be necessary to prevent excessive deflection.

3. What is the difference between a simple beam and a cantilever beam?

A cantilever beam is a type of beam that is supported at only one end, while the other end is free to rotate. In contrast, a simple beam is supported at both ends and is free to rotate at those supports.

4. What is a moment in statics?

A moment, or bending moment, is a measure of the internal forces that cause a structural element, such as a beam, to bend. It is calculated by multiplying the force applied to the beam by the distance from that force to the point of interest on the beam.

5. How do you calculate the reactions at the supports for a simple beam with one moment?

To calculate the reactions at the supports, you need to consider the equilibrium of forces and moments acting on the beam. The sum of the forces must be equal to zero, and the sum of the moments must be equal to the moment at the point of interest. By setting up and solving equations based on these principles, you can determine the reactions at the supports.

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