MecMovies 4.0 : M15.3: Principal Stresses in a Rectangular Tube Beam

scene 6 of 14

Constructing the moment diagram

Considering the segment
from $x = 3 m$ to $x = 7 m$

  area under shear
      diagram $= + 16.00 k N - m$
  concentrated
     moments $= 0.00 k N - m$
  change in bending
     moments $= + 16.00 k N - m$

  at $x = 3 m$ ,    $M = - 7.00 k N - m$
  change in bending
         moment       $= + 16.00 k N - m$
  at $x = 7 m,$    $M = + 9.00 k N - m$