When we apply a vertical shear force Sy and the structure is symmetric about x axis, then why is it logical to have the position of shear center at the location of intersection of line of action of shear force and x axis?
If we go by basic definition then the moment about the shear center due to shear forces should be 0, so the line of action of external shear force is logical, but when we consider moment about x- axis, rather than getting cancelled, I think they get added.
eg. This is the situation.
Now look at the final solution depicting the shear flows
So as I suggested, instead of moments being equal and opposite, I think they exactly equal in magnitude and direction. So where am I getting a wrong interpretation?
EDIT:- I tried to keep the question general and explained accordingly, to be specific the question is as follows:-
The thin-walled single cell beam shown in Fig. 20.11 has been idealized into a combination of direct stress carrying booms and shear stress only carrying walls. If the section supports a vertical shear load of 10 kN acting in a vertical plane through booms 3 and 6, calculate the distribution of shear flow around the section.
Boom areas: B1 =B8 =200mm2, B2 =B7 =250mm2, B3 =B6 =400mm2, B4 = B5 =100mm2.
x is horizontal and y is vertical
It is a closed section beam. An idealized version of an airplane wing