The current seismic design code prescribes structural wall should be designed as special shear wall when building height is more than 60m and seismic design category D. The design code for the irregular wall is not provided. Therefore, the special wall with flange is designed as linear section wall. The ultimate strain of concrete in nonrectangular section would be different form that in rectangular section, then the equation of discrimination for special wall would changed. In the study, nonlinear analysis for linear and irregular wall are performed, and concrete ultimate strain is compared.