What is the Correct Value of Dx in Frame Analysis?

In summary, the problem involves calculating forces on a frame using the equations ƩFx=0, ƩFy=0, and ƩM=0. The correct values for E and Ax have been found, but the values for Bx and By are incorrect. The force at B does not necessarily act along the member assumed and there seems to be no other way of solving the problem. However, after considering the values for CDE, the problem is solved by summing the moments about C and solving for the remaining unknowns on ABD.
  • #1
yaro99
75
0

Homework Statement


pErlIgy.png



Homework Equations


ƩFx=0
ƩFy=0
ƩM=0


The Attempt at a Solution



For the entire frame:
ƩMA = 0: -360*15 -240*33 + E*12 = 0
E = 1110 lb →
ƩFx = 0: 1110 - Ax = 0
Ax = 1110 lb ←
These are the correct values so far.

Member BC:
W0a04tA.png


By = (4/3)*Bx

ƩMC=0: -240*9 + 360*9 + Bx*12 - (4/3)*Bx*18 = 0
Bx = 90 lb
By = (4/3)*90 = 120 lb

These values are incorrect.
 
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  • #2
Does the force at B necessarily act along the member as you have assumed?
 
  • #3
TSny said:
Does the force at B necessarily act along the member as you have assumed?

Hmm I guess it doesn't.
But I can't find another way of doing the problem. Every member seems to have 4 unknowns when isolated.
 
  • #4
What can you learn from CDE?
 
  • #5
TSny said:
What can you learn from CDE?

Ah, I figured it out now, thanks!

I only need the value of Dx so I summed the moments about C.
Then I solved for the three unknowns left on ABD.
 

What is the purpose of analyzing frames in statics?

The purpose of analyzing frames in statics is to determine the internal forces and reactions acting on the different members of a frame structure. This allows for the evaluation of the stability and strength of the frame and helps in the design and construction of safe and efficient structures.

What are the main components of a frame structure?

The main components of a frame structure are the members, joints, and supports. Members are the individual elements that make up the frame, such as beams and columns. Joints are the points where the members connect and transfer forces. Supports are the points where the frame is attached to the ground or other structures.

What are the different types of loads that can act on a frame?

The different types of loads that can act on a frame include point loads, distributed loads, and moments. Point loads are forces applied at a single point on a member. Distributed loads are forces applied over a certain area or length of a member. Moments are rotational forces that can cause twisting in the frame.

How is the stability of a frame determined?

The stability of a frame is determined by analyzing the reactions at the supports and checking if they are within the limits of the frame's capacity to resist movement. The frame must also be able to resist external loads without excessive deformation or failure. Additional considerations include the arrangement and bracing of the members to prevent buckling and instability.

What methods are used to analyze frames in statics?

The two main methods used to analyze frames in statics are the method of joints and the method of sections. The method of joints involves analyzing the forces and reactions at each joint in the frame. The method of sections involves cutting the frame into sections and analyzing the forces and reactions within those sections. Both methods use the principles of equilibrium and free body diagrams to solve for unknown forces.

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