Special moment resisting frames have unique structural characteristics. In these frames lateral resistance is provided through rigid connections, so the proportioning of beams and column plays an important role in future behavior. But less attention has been made on the importance of panel zone area in overall behavior of frame. Reduced beam sections have been introduced after 1994 Northridge earthquake as an improvement to connection behavior. But they are rather expensive. To reduce the cost, drilled flange connection have been introduce and recently improved. In this research effect of panel zone has been studied in a 4 story and a 16 story moment frame structure using collapse probability and fragility curve and drilled flange connection combined with 4 stiffness variation of Panel zone, for near field ground motions. The results show that stiffness of panel zone has considerable effect on probability of failure and best results can be obtained using stiffer panel zone in the allowable range of the guidelines.