Fixed end moments is it WL^2/12 or WL/12 ?

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In summary, When calculating the moment at the fixed ends of a horizontally fixed end supported beam with an equally distributed load, the equation WL/12 should be used if W is the total weight of the load, and wL^2/12 should be used if w is the uniformly distributed load. The units of moment must be in force time length units (Newton-meters or foot-pounds).
  • #1
mar1wan
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Homework Statement


Hello Every one, well i have a question regarding the Fixed End moments, if we had a Horozontally Fixed End supported Beam, with equally distributed load (W) on the beam, and we require the moment at the fixed Ends, which Equation would i use:




Homework Equations


1: WL2/12
2:WL/12


The Attempt at a Solution


my search did not give me a clear difference betwen the two, for Equation "1" this google book search :http://books.google.co.uk/books?id=...0CB4Q6AEwAw#v=onepage&q=wL/12 moment&f=false" , its a book called "Structure and architecture"
By Angus J. MacDonald page 143, and for equation "2" pretty much every thing i learned, well at least i think i did:confused:, can someone please calrify the difference,
thank you
 
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  • #2
If W is the TOTAL weight of the distributed load in force units, then M= WL/12. If w is the uniformly distributed load in units of force per unit length, then M =wL^2/12. Note that W =wL. Confirm that the units of moment must be in force time length units (Newton-meters or foot-pounds).
 
  • #3
OK thanks a lot PhanthomJay, now i see how it works
 

Related to Fixed end moments is it WL^2/12 or WL/12 ?

1. What is the equation for calculating fixed end moments?

The equation for calculating fixed end moments is WL^2/12 or WL/12, depending on the specific scenario and boundary conditions.

2. How do I determine the value of W in the fixed end moment equation?

The value of W represents the load applied to the beam. This can be determined by considering the forces and loads acting on the beam, such as point loads, distributed loads, and reactions at fixed supports.

3. Is the fixed end moment equation always accurate?

The fixed end moment equation is a simplified calculation and may not always accurately represent the behavior of a real-world beam. Factors such as beam material, support conditions, and load distribution can affect the accuracy of the equation.

4. Can the fixed end moment equation be used for all types of beams?

The fixed end moment equation is commonly used for simply supported beams with uniform loads. However, it may not be applicable for other types of beams, such as cantilever beams or beams with varying loads. In these cases, other methods of analysis may be needed.

5. How do I apply the fixed end moment equation in real-world scenarios?

To apply the fixed end moment equation, you need to have a clear understanding of the beam's boundary conditions, loadings, and other relevant factors. It is also important to carefully label and consider the signs and directions of forces and moments in the equation to obtain accurate results.

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