Cantilever beam (statically indeterminate)

In summary, the conversation is about a person seeking help in calculating a loading case for a cantilever beam. They have found various loading cases but are unable to solve a specific one. They have written a bending moment equation and are seeking hints and advice. Another person suggests using superposition to solve the problem. The original person has solved a part of the question but cannot continue without the equilibrium equations. However, using only the equilibrium equations will not solve the problem. The suggested solution is to use superposition and equate the deflection from the load acting without the roller support to the deflection from the roller support reaction acting without the load.
  • #1
durka
2
0
hello everyone,
i have a small problem in calculating a particular loading case of a cantilever beam which is shown on the attached image.

i have found many loading cases of cantilever beams which i am able to solve, however for this one i couldn't find anything unfortunately.

the bending moment equation which i have written is:
M(x)= -Mw+Rwx-R[x-0.4] which i hope is correct



determined needs to be:
a) The maximum deflection at the loading point (695N at 0.4)
b)The maximum values of the reactions at the supports.

for any hints and advices i will be grateful

best regards
durka
 

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  • #2
The answer is superposition. You know (or can derive) the equation(s) for a cantilever beam (w/o the 2nd support) with a point load. Consider this case to be the sum of two independent loadings, the 2nd of which is at the end of the beam in the upward direction (instead of the support), with a physical constraint that the net displacement of the end of the beam is zero.
 
  • #3
hello hotvette,
thanks for your quick answer.

i have solved a part of the question, but i can not continue because i don't have the equilibrium equations.

i came to the point:
EI DELTA=Mw0.08-Rw0.0106+Rp0.0106-Rp0.032

i don't get any further because the equilibrium equations that i have used don't make any sense so i canot solve it.

i know that i must replace either Rp or Rw and Mw from the equilibrium equations
 
  • #4
You cannot solve this from the equilibrium equations alone.

If you follow Hotvette's suggestion an use superposition, you should be able to calculate the cantilever deflection from the load acting without the roller support and equate it to the deflection from the roller support reaction acting without the load.
 

1. What is a cantilever beam?

A cantilever beam is a structural element that is fixed at one end and free at the other, allowing it to support a load without any additional support or bracing.

2. What does it mean for a cantilever beam to be statically indeterminate?

A cantilever beam is statically indeterminate when the reactions and internal forces cannot be determined solely by the equations of static equilibrium. This means that additional equations or methods, such as the slope-deflection method, must be used to analyze the beam's behavior.

3. How do you calculate the reactions and internal forces of a statically indeterminate cantilever beam?

The reactions and internal forces of a statically indeterminate cantilever beam can be calculated using the slope-deflection method, the moment distribution method, or by solving a system of equations using compatibility equations.

4. What are the advantages of using statically indeterminate cantilever beams in structural design?

Statically indeterminate cantilever beams allow for more efficient use of materials and can withstand larger loads compared to statically determinate beams. They also offer more design flexibility and can be used in a wider range of structural configurations.

5. What are the limitations of using statically indeterminate cantilever beams?

The main limitation of using statically indeterminate cantilever beams is the added complexity in analysis and design. This requires a more advanced understanding of structural mechanics and calculations, making it more challenging for beginner engineers to work with. Additionally, the use of additional equations and methods may also increase the chances of error in the analysis process.

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