Can a 25kN Force Affect the Moment at the Fixed Support in Beam Analysis?

[PK1248]

Homework Statement

Okay, I am required to analyse the beam solving for all unknown reactions, both internal and external. From there, the Bending Moment Diagram and Shear Force Diagram are to be produced.

Homework Equations

The Attempt at a Solution

So i sectioned the beam at the internal hinge and using the left hand beam and statics, was able to determine the shear at the hinge to be 20kN. From that, i was able to determine the reaction at the roller (80kN upwards).

On the right hand beam, i have taken moments about the fixed support. I have a moment supplied by the shear (60kNm clockwise) and a moment supplied at the fixed support (M) as well as the moment applied by the bent member.

That relates to the issue. I'm confused as to the moment generated by the 25kN force. I feel as though the 2.5m dimension on the right of the image is a red herring. That is, the force acts vertical and so by definition, there would be no moment as the force acts parallel to the 2.5m dimension.



Any help would be greatly appreciated

 

[SteamKing]

If you are not certain, you can always calculate the vector product r x F, where r is the position of F w.r.t. the attachment point on the beam.

 

[pongo38]

Does this help? Add a 25 kN force downwards at E, and then add another 25 kN Force upwards at E. You then have a force and a couple.

 

[pongo38]

quote "On the right hand beam, i have taken moments about the fixed support. I have a moment supplied by the shear (60kNm clockwise) and a moment supplied at the fixed support (M) as well as the moment applied by the bent member."
Don't forget the effect of the reaction at B.

(This makes an interesting question in qualitative analysis. From the bending moment diagram you should be able to determine the deflected shape and whether the hinge at C goes up or down, without calculation)

 

[rezeew]

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As a scientist, it is important to carefully analyze all aspects of a problem before coming to a conclusion. In this case, it seems that the 25kN force may not actually contribute to the moment at the fixed support because it is acting parallel to the 2.5m dimension. However, it is important to consider the possibility that this force may have a component that is perpendicular to the 2.5m dimension, which would contribute to the moment. It may also be helpful to consider the direction of the force and how it affects the overall equilibrium of the beam. I would suggest double-checking your calculations and considering all possible factors before making a final determination. Additionally, seeking guidance from a professor or experienced engineer may also be beneficial in solving this problem.