Reaction force calculations and questions
Reaction force calculations and questions
(OP)
Here is a simple one...
I am trying to calculate force at A & B.
The L shape is a simple beam.
so summing the force at the center of the beam
A-B=1700 -------(1)
summing the moment at the center of the beam, assuming anti-clockwise is positive
-3.699A - 5.676B = 9.498 (1700) ------(2)
solving those equation give me
A = -693#
& B = -2393#
so that means I will have a force of 693# at A pointing downward and 2393# at B pointing upward. ie..direction of force for A & B flipped to the drawing.
Assuming the method I do this is correct, wouldnt the force direction should be as the diagram shown. The 1700# will try to tilt line A-B. Why are the calulcated force shown different?
I am trying to calculate force at A & B.

The L shape is a simple beam.
so summing the force at the center of the beam
A-B=1700 -------(1)
summing the moment at the center of the beam, assuming anti-clockwise is positive
-3.699A - 5.676B = 9.498 (1700) ------(2)
solving those equation give me
A = -693#
& B = -2393#
so that means I will have a force of 693# at A pointing downward and 2393# at B pointing upward. ie..direction of force for A & B flipped to the drawing.
Assuming the method I do this is correct, wouldnt the force direction should be as the diagram shown. The 1700# will try to tilt line A-B. Why are the calulcated force shown different?





RE: Reaction force calculations and questions
Alternatively, stick with the force-directions as shown on your diagram, and listen to your arithmetic.
RE: Reaction force calculations and questions
Quando Omni Flunkus Moritati
RE: Reaction force calculations and questions
Your maths workout just fine, I find it easier to take moments about either A or B and eliminate one unknown reaction.
You made an assumption about which direction the reactions were in at the start and if your assumption is incorrect then the force gets the opposite sign.
You can see easily which direction the reaction forces have to go to maintain equilibrium by assuming your standing a point B which is a pivot point and the 1700 acting clockwise, it should be clear the reaction at A needs to point down, conversely the reaction at B when standing at A needs to go up.
RE: Reaction force calculations and questions
RE: Reaction force calculations and questions
Ted
RE: Reaction force calculations and questions
are you complaining about the detail of the part between A and B ?
as far as i can see all the necessary information to calculate the reactions at A and B is there ...
Quando Omni Flunkus Moritati
RE: Reaction force calculations and questions
RE: Reaction force calculations and questions
Quando Omni Flunkus Moritati