I am designing a structure as per Canadian S16-01 code and have changed the value of LY significantly for one of the members. The utilization ratio however does not change. Why is that ?
There is a clause at the end of section 13.8.2 of the S16-01 code which requires Mfx/Mrx + Mfy/Mry <=1.0. Thiscondition is becoming critical in your case and as this condition is not affected by the axial capacity, you are not seeing any change to the utilization ratio when you are changing the LY. The axial capacity is increasing due to reduction in LY value which you may confirm by checking a TRACK 2 output, but it is not affecting the utilization ratio in this case.