Distribution of Shear Stress in Sections Calculation of Q revisited


Recall the definition of Q.

Q is the first moment of the area between the location where the shear stress
is being calculated and where the shear stress is zero.


Q = A ybar


where A is the area between the location where the shear stress is zero and the location
where the shear stress is being calculated and ybar is the distance from the neutral axis to
the centroidal axis of A.

Key points in the calculation of Q are that you must identify the location in the x-section
where the shear stress is zero. Also note that for symmetric x-sections, the shear stress distribution must also be symmetric. Further note that the maximum shear stress occurs
at the neutral axis. Consider the cases shown below where z is the neutral axis.



Click here for four other cases.

 



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