Irregular structure refer to buildings or other structures that deviate from standard design principles and geometric shapes. Based on previous studies, one of the factors that cause failure to the irregular structure is the asymmetrical shape which cause uneven load distribution to the structure. Therefore, this study aims to evaluate the irregular structure building and bracing type X on this structure. The parameters that being evaluate are period, modal participating mass ratio, base shear, story drift and DCR. The modelling process are done using ETABS which is an element-based structural modelling software. The results indicate there are failure occurred in the structure on existing condition in terms of modal participating mass ratio, story drift, and also DCR. Model with bracing type X indicate a reduction in the period as well as the rotation Z (RZ) of the mass participating. Story drift on the model with bracing type X also indicate a significant reduction, yet on the model 1,3, and 5 the story drift value haven’t met the story drift requirement. The DCR value of column and beam on the model with bracing type X also indicate a reduction, however there are some element on the structure that haven’t met the requirement on model 1,3, and 5. The bracing placement on the corner of the structure present a more significant effect to the structure.

Keywords: Irregular structure, bracing type X, ETABS, story drift, periode, modal participating mass ratio, base shear, DCR