shear stress at boundary of beam

[johnson9883]

In my book , it's stated that the at the boundary , the shear stress in beam = 0 .

 

However , wheni tried the circled equation , i didnt get shear stress = 0 .

 

What;s wrong with it ? Is the concept of at the boundary , the shear stress in beam = 0 . correct ?

 

http://imgur.com/a/k9geD

 

 

http://imgur.com/a/KKCGR

Edited November 5, 2016 by johnson9883

[studiot]

 

 

However , wheni tried the circled equation , i didnt get shear stress = 0 .

 

Could it be your arithmetic?

 

At the boundary,

 

[math]y = \frac{h}{2}[/math]

So substituting

[math]Q = \frac{1}{2}\left( {\frac{{{h^2}}}{4} - {y^2}} \right)b = \frac{1}{2}\left( {\frac{{{h^2}}}{4} - {{\left( {\frac{h}{2}} \right)}^2}} \right)b = 0[/math]