Calculating Reactions and Bending Moments for Fixed End Beam

AI Thread Summary
The discussion focuses on calculating reactions and bending moments for a fixed-end beam subjected to two loads. The user has attempted to find the reactions Ra and Rb but is getting inconsistent results, particularly with Rb and the moments Ma and Mb. Clarification is sought regarding the beam's configuration and the user's background in structural analysis. Suggestions include providing a free body diagram, confirming the fixed ends, and consulting structural analysis textbooks for better understanding. The importance of ensuring the sum of reactions equals the total load is emphasized for accurate calculations.
bakoo
Messages
19
Reaction score
0

Homework Statement



Fixed end beam with

Length = 1m
Load 1 = 58.86n @ 0.4m from A
Load 2 = 39.24n @ 0.85m from A

Find Ma, Mb, Ra, Rb


Homework Equations



Not Sure, where help is needed


The Attempt at a Solution



Well i think, almost sure from 2 methods that Ra = 40.52511

I have tried to calculate Rb but keep getting different answers, so far i have got

Rb = 32.06 and Rb = 57.57

I think Ma is -9.22, but not 100%. Keep getting different answers for Mb, 9,903 and Mb 2.7 and Mb
 
Physics news on Phys.org
To find the bending moments, you need the support reactions first, then you need to cut the beam into pieces, and then sum the moments independently, from the first whole piece.

Can you please provide more information for this question, such as, where is A, is A the fixed end, or the open end? Providing a free body diagram of what you done would be helpful too.
 
Since the Moments and reactions of both ends are required, I assume that the beam is fixed at both ends. Could you please confirm?
At this point, if the sum or Ra and Rb is not 98.1, you are in trouble.

Before we go further, may I enquire if you have already done some work on indeterminate structures? It will be first year university in engineering or equivalent, or higher. What have you learned so far from the course. Do you have textbooks on structural analysis, such as "Theory of Structures" by Stephen Timoshenko,
https://www.amazon.com/dp/0070648689/?tag=pfamazon01-20
This book is sure to be found in all university libraries. You could use any other ones.

On second thought, if you have done Strength of Materials, you might have the tools required to solve the problem analytically.

How did you get your Ma and Mb. Could you post your calculations, even if you think they may be wrong?
 
Last edited:
If you only need an answer as most practising engineers do, the following link gives the formulae for different loading and boundary conditions:
http://www3.hi.is/~thorstur/teaching/cont/Continuum_CommonBeamFormulas.pdf

As it is a .pdf file, the display of the page will take some time (a couple of minutes).

If you are doing the problem for a course, I suggest you work on your teacher's notes supplemented by a good textbook.

Feel free to post questions after you have studied the subject.
 
Last edited:
Back
Top