Bending Moment for Simply Supported, Overhanging Beam with two Overhangs

In summary, the bending moment for a simply supported beam with two overhangs is determined by analyzing the distribution of loads and reactions at the supports. The beam experiences bending moments due to external forces, which vary along its length. The calculation involves identifying the locations of maximum moments, typically occurring at the supports and overhangs, and applying the principles of static equilibrium. Diagrams and equations are used to visualize and quantify the bending moments at critical points, aiding in the design and assessment of structural integrity.
  • #1
benwb93
3
0
Homework Statement
Bending Moment for Simply Supported, Overhanging Beam with
Two overhangs
Relevant Equations
Bending Moment
1713737517466.png

This formula works for a beam with one uniformly distributed load... How would I apply the same technique to get the bending moment equation in terms of x for the same type of scenario with a point load before R1 and after R2 at each end of the overhangs? Would I simply add a term for each the positive and negative bending moment to the already provided R1x-w(a+x)^2/2 ?
 
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  • #2
Welcome, @benwb93 !

What formula (which works for a beam with one uniformly distributed load) are you referring to?
Could you post an image with better quality for us to be able to see its details?
Could you also post a handmade diagram of the situation that you describe?
 
  • #3
I am looking to solve the Mx moment equation in terms of x for the same scenario in the situation posted above, but with the uniform load replaced by two point loads at each end of the overhangs. This is what I am trying to formulate:
1713752943803.png

these two point loads are overhanging the same distance from each furthest bearing, instead of using the uniformly distributed load, I want to apply this formula to this situation with 2 point loads.

Formula above originated from here: https://www.linsgroup.com/MECHANICAL_DESIGN/Beam/beam_formula.htm
 
  • #4
1713755873049.png

Essentially, I want the sum of moments about this shaft

My assumptions is it would be something like:

Summing moments at 0
M=-Fp(a)+R1(b)+R2(c)-R3(d)+Fg(e)

but instead I want to formulate it as a function of x where I can write it as shown in the formulas above, M(x)=R1x-w(a+x)^2/2

If I do this and sum up the moments this is what I get:
1713760563503.png

for some reason im not positive that this is correct as I havent done much CE/strengths of materials in awhile
try to ignore the smudges from my scanner and the random change into meters in the final solution

there would be another orthogonal set of planes with another moment reaction obviously but is this formulation correct as it stands so far?
 

FAQ: Bending Moment for Simply Supported, Overhanging Beam with two Overhangs

What is a bending moment in the context of a simply supported beam?

A bending moment in a simply supported beam refers to the internal moment that induces bending in the beam due to external loads applied to it. It is a measure of the tendency of a force to cause the beam to rotate about a point or section. In a simply supported beam with overhangs, the bending moment varies along the length of the beam, influenced by the position and magnitude of the loads as well as the reactions at the supports.

How do you calculate the bending moment for a simply supported, overhanging beam?

To calculate the bending moment for a simply supported, overhanging beam, you first need to determine the reactions at the supports using equilibrium equations (sum of vertical forces and sum of moments). Once the reactions are known, you can use them along with the applied loads to calculate the bending moment at various points along the beam using the formula: M(x) = R_A * x - Σ(P * d), where M(x) is the bending moment at distance x from the left support, R_A is the reaction at the left support, P is the applied load, and d is the distance from the load to the point where the moment is being calculated.

What is the significance of the maximum bending moment in beam design?

The maximum bending moment is crucial in beam design because it determines the required strength and material properties of the beam. Engineers must ensure that the beam can withstand this maximum moment without failing. The design typically involves selecting an appropriate cross-section and material that can handle the maximum bending stress, as indicated by the bending moment, according to the material's yield strength and safety factors.

How does the presence of overhangs affect the bending moment distribution?

The presence of overhangs in a beam alters the bending moment distribution by introducing additional moments at the supports and along the length of the beam. Overhangs can create negative moments at the support where the overhang begins and positive moments further along the beam. This results in a more complex bending moment diagram, which must be analyzed to accurately determine the maximum and minimum moments throughout the beam.

What is the typical shape of the bending moment diagram for a simply supported beam with two overhangs?

The bending moment diagram for a simply supported beam with two overhangs typically consists of a combination of linear segments and parabolic shapes. The diagram starts at zero at the supports, rises to a peak (maximum positive moment) under the applied loads, and then may drop to a negative value at the overhangs. The exact shape depends on the load configuration and magnitudes, but generally, it reflects the variations in bending moments along the beam due to both the internal moments from the loads and the reactions at the supports.

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