In the notes , the author stated that when the force is applied through the centorid of cross section , the channel will bend and twist. but , on the second page , the author stated that the shear center lies on an axis of symmetry of member's cross sectional area... So, i am confused whether the member will twist or not when the force P is applied thru the centroid or shear center .... Why the shear center is located at O , which is located outside of the C channel ? In the notes , it's also stated that to prevent twisting , the P should be applied at O , does it mean we have to apply the force thru the centoid and also at the O at the same time to prevent twisting ? i'm confused Is there anything wrong with the notes ?