distrbution of stress in sections of castellated beam in elastic and plastic condition

many researchers have been efforted to identify the shape of distribution of stress and strength of castellated beam and base on that, offer a method for design that members. through this methods, comparing virendil method by simplicity and reasonable results, have been used widly. regardless from shortcoming of this method, there is two idea for distribution of stresses via primary bending in t- section. in this paper we have tried by modeling of castellated beams which tested in refrence [3] and analyzing them in plastic and elastic condition, the shape of distribution of normal and shear stress studied and finally we conclude that if primary bending stress distribution bee assumed uniform, better result will bee obtain. also the maximum value of normal stress in flang occure in correspond area with middle length of skew edge of opening.