3 Member force system-Could use some input

In summary: But that would defeat the purpose of having a post.In summary, the static problem is to find the reactions at the fixed support (where the beam is cemented into the ground).
  • #1
M98Ranger
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I have a simple statics problem that I am trying to solve. The rigid body to be analyzed is an upside down L-shaped beam connected together at the corner by a pin. The object has a height of 4.5 meters vertically, by 3.5 meters in the horizontal. Additionally, the object is secured to the ground by means of a fixed support (cemented into the ground). In the corner of the upside down L connected diagonally is a structural element connected by pin joints at both ends. The lower end of the structural element is connected to the upside down L object 3 meters above the ground. The higher end is connected two meters from the corner of the L.

One 3kn force (straight down) is applied at 1 meter from the corner of the upside-down L-shaped object on the horizontal member. On the same member at the very end (3.5m from the corner) is a 2kn force applied straight down. Lastly there is a given 4kn force applied applied horizontally at a point 3.5 meters above the ground on the vertical member of the upside down L.

PS: I have tried to work it out on my own by combining the 3 and 2kn forces and then summing the moments about the fixed support. And summing the forces in the X and Y. I am not happy with my answers though and would like to know what someone else thinks about it. Additionally I have been reading everything I could on the internet since morning.

PHEW! Here is my question. It seems to me that I have a 3 force member problem here. But I am not sure how to deal with the 4kn force. It seems to me that the 4kn force and the X componant of the force at the corner of the upside down L would make a force couple.

As a three-force member is defined as a rigid body with no force couples, acted upon by a system of forces composed of or reducible to, three forces at three different locations I am not sure what I have here. How do I deal with the 4kn force?

SOLVE...find the reactions at the fixed support (where the beam is cemented into the ground).
 
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  • #2
In order to solve a problem one needs to know what is to be solved for. You have not supplied this information...:wink:
 
  • #3
A picture would be nice :smile:, but so far is an isostatic problem.
 
  • #4
There I edited my original post. So far as a picture... I wish I could, but I don't know how. Any suggestions? I could find a similar picture and try to cut and paste it into a post.
 

1. What is a 3 member force system?

A 3 member force system is a type of mechanical system that consists of three forces acting on an object or structure. These forces can be either concurrent or non-concurrent, and their magnitudes and directions determine the overall stability and equilibrium of the system.

2. How do you calculate the resultant force in a 3 member force system?

The resultant force in a 3 member force system can be calculated by using the principle of vector addition. This involves breaking down each force into its horizontal and vertical components, then adding all the horizontal components together and all the vertical components together. The resultant force can then be found using the Pythagorean theorem.

3. What is the difference between a concurrent and non-concurrent 3 member force system?

A concurrent 3 member force system is one in which all three forces intersect at a common point, while a non-concurrent system has forces that do not intersect. This difference can affect how the forces are calculated and how they affect the stability of the system.

4. How does the angle between forces affect a 3 member force system?

The angle between forces in a 3 member force system can greatly impact the overall stability and equilibrium of the system. If the forces are not evenly distributed or if they are not in the correct direction, it can result in a net torque or moment which can cause the system to rotate or become unbalanced.

5. What are some real-life examples of 3 member force systems?

Some common examples of 3 member force systems include trusses, cranes, and bridges. These structures rely on the equilibrium of three forces to maintain stability and support weight. Other examples can be found in everyday objects such as ladders, bicycles, and even human joints like the elbow or knee.

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