Beam Deflection by Double Integration

 

* Example:  The beam  ABC of length L and flexural rigidity, EI, is subjected to a uniformly

distributed load as shown below.  Find the deflection of the beam in the first half and second half

of the beam.

 

                              

 

 

Strategy:  Replace the distributed load with an equipollent, concentrated load  wL/2

acting at L/4.

                     

 

Use equilibrium equations to determine support reactions.

 

       → ∑ Fx  =  0,    Ax  =  0,            Fy =  0,    Ay  +  Cy  ˗  wL/2  =  0

 

      ccw    MA  =  0,   Cy (L)  ˗  wL/2 (L/4)  =  0,  Cy  =  wL/8  (result)

 

and    Ay  =   ˗  Cy  +   wL/2  =  0      So   Ay  =   3wL/8

           

The loads acting on the beam changes at mid-span.  So break the beam into two

sections,  0    x    L/2    and   L/2    x     L  and construct a free body diagram

of each section to determine the bending moment distribution for each section.

 

 

Click here to continue this example.

 


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