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Homework Help: Deflection of a beam by successive integration

  1. Aug 6, 2013 #1
    1. The problem statement, all variables and given/known data

    A beam is built in at its end supports A and B, and is subject to a mid-span point load F. Using the method of successive integration, determine an expression for the deflection of this beam. Calculate the maximum deflection. Ignore any axial load effects.

    2. Relevant equations


    3. The attempt at a solution
    My attempt at the solution is pretty useless as far as I can tell. Any examples I can find online only demonstrate with a UDL and I am having trouble translating the information to my midspan point load.

    My aim is to construct an equation for the moment in the beam. Integrate this equation twice to obtain an equation for the deflection of the beam. Using the boundary conditions that are applicable for a fixed end I will solve for the constants of integration and whaa-la I should have an answer.

    Not so simple when I apply my method...

    When it comes to creating an equation for the moment in the beam I am getting that the moment is 0 so when I integrate twice to obtain an equation for deflection I am only left with two integration constants that also equal 0.

    Knowledge dictates the deflection cannot be zero.

    If there is some hero out there that can help me solve this problem I will be forever in debt to you. I have an exam in about 24 hours and this question is worth 10%

    Thank you in advance!
  2. jcsd
  3. Aug 7, 2013 #2
    Start with V(x) for the left half of the beam. It should be a constant. Integrate it, and try to determine the arbitrary constant from the end conditions of the beam.
  4. Aug 7, 2013 #3


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    Staff Emeritus
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    Homework Helper

    To amplify what pongo38 said, start by constructing a shear and moment diagram for your beam. Some of the reactions may be unknown, but by constructing the necessary integrals and applying the correct boundary conditions, these unknowns can be determined. Don't disregard the example with the UDL; it will help you structure your calculations.
  5. Aug 8, 2013 #4
    Thank you so much guys, I am just about to head to the exam and have just figured out my problem! You ledgends!!!
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