Calculation of Bending Moments and beam deflection

In summary, the problem involves a beam with a module of rigidity EI and the task is to determine the reactions at the supports and the equation of the deflection curve of the left half of the beam. The relevant equations are v*EI=((Ma*x2)/2)+((Ra*x3)/6), Ʃ of Forces in Y direction = Ra+Rb=0, and Ʃ Moments about A = Ma-Mo+Mb-Ra*L. The approach to solving the problem is to use double integration of the bending moment curve and the boundary conditions at the ends of the beam. The beam is also statically indeterminate.
  • #1
mm391
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Homework Statement



The picture of the beam below has a module of rigidity EI, determine the reactions at the supports and the equation of the deflection curve of the left half of the beam

Homework Equations



v*EI=((Ma*x2)/2)+((Ra*x3)/6)

Ʃ of Forces in Y direction = Ra+Rb=0
Ʃ Moments about A = Ma-Mo+Mb-Ra*L

The Attempt at a Solution



How do I go about finding Ra and Rb and Ma and Mb?

For the left had side of the beam the bending moment equation is Ma+Ra*x

Putting x = L/2 into the defelction equation gives me:

((Ma*L^2)/(8EI))=((-Ra*L^3)/(48EI))
 
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  • #2
Where's your picture of the beam?
 
  • #3
Sorry I forgot to add the picture. It should be attached now.
 

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  • #4
The beam is statically indeterminate. You'll need to use double integration of the bending moment curve and the boundary conditions at the ends of the beam to solve for the reactions and moments at the ends.
 
  • #5



I would first clarify any uncertainties about the given information and equations. For example, I would ask for the units of the given parameters (such as EI) and ensure that all units are consistent throughout the calculations. Additionally, I would verify the assumptions made in the calculation, such as the beam being in a static equilibrium and the material having a linear elastic behavior.

Next, I would use the given equations and apply the principles of equilibrium to solve for the unknown reactions and bending moments. This may involve setting up a system of equations and using algebraic manipulation to solve for the unknown variables.

Once the reactions and bending moments are determined, I would use the equations for bending moments and deflection to calculate the deflection curve of the left half of the beam. This would involve substituting the known values into the equations and solving for the deflection at various points along the beam.

Finally, I would critically evaluate the results to ensure they make sense and are within the expected range. If there are any discrepancies, I would review my calculations and assumptions to identify any potential errors.

In conclusion, as a scientist, I would approach this problem by first clarifying any uncertainties, applying the principles of equilibrium, and critically evaluating the results to ensure accuracy.
 

1. What is the purpose of calculating bending moments and beam deflection?

The purpose of calculating bending moments and beam deflection is to understand how a structural element, such as a beam, will behave under applied loads. This information is essential in designing and analyzing structures to ensure they can safely support the intended loads.

2. How do you calculate the bending moment of a beam?

The bending moment of a beam can be calculated by multiplying the applied load by the distance from the load to the point of interest. It is important to consider the direction of the load and the orientation of the beam when determining the sign of the bending moment.

3. What factors affect the deflection of a beam?

The deflection of a beam is affected by several factors, including the material properties of the beam, the magnitude and location of the applied load, and the beam's shape and supports. The type of loading, such as point loads or distributed loads, also plays a role in determining the deflection.

4. How do you calculate the deflection of a beam?

The deflection of a beam can be calculated using various methods, such as the moment-area method or the double integration method. These methods involve solving equations that take into account the beam's properties, loading, and supports. Computer software and finite element analysis can also be used to accurately calculate beam deflection.

5. How does beam deflection affect the structural integrity of a building?

Excessive beam deflection can significantly impact the structural integrity of a building. It can cause cracking, displacement, and even failure of the structural elements. Therefore, it is important to accurately calculate and control beam deflection to ensure the safety and stability of a structure.

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