What Do You Do When A/B Forces Aren't Shown?

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When analyzing a beam with a downward force applied at its center, the reactions at supports A and B can be calculated as equal, each being half the total load (RA = W/2, RB = W/2). If the load is offset from the center, moments about either support can be used to determine the reactions. The absence of upward forces at A and B in the problem raises questions about the validity of the statics scenario. It's essential to clarify whether any forces are acting at the supports, as this is fundamental to solving statics problems. Understanding these principles is crucial for accurately drawing shear and bending diagrams.
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Hi everyone,

I have a problem question in my statics class and one problem askes to draw the shear and bending diagram for the problem.

It shows the beam ------------------------ with the reaction pushing down on the top/middle of it and A and B on each side but shows no forces pushing up on each side which I am stuck on.

-------------------------
A B
^ ^
| |
| |
| ? |?

Every other example in the book shows forces pushing up on A/B but not the questions.

If it showed them I wouldn't be stuck...what do I have to do in this case?

Thanks so much!
 
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Hint: If you wrap "code" tags around your "diagram" (in the post/editing area) then it will show up better.

Question:Is there a force (load) acting down in the middle of the beam AB ? Or is it slightly offset from the centre ?

If it's in the middle, then the reactions at A and B are: RA = W/2 and RB = W/2.

If it's slightly offset, then you will have to take moments about A, or B, to determine the exact value of RA and RB.
 
Well if there's a load on the beam and A and B are labeled but no forces are shown... there better be forces at A and B or this isn't statics my friend!
 
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