Milad Ebrahimnejad, - Assistant Professor, University of Guilan, Iran,
Mohamad Rahmati - M.Sc. Student of Structural Engineering, Institute of higher education of Acecr of Rasht, Iran,

Todays the irregularity of buildings is an inevitable issues in structural industry. Accordingly, it is so consequential to study on the structural response of the irregular building under earthquakes. Pyramid-shaped building is one of the types of vertical geometric irregular structures, which has been constructed recently. In this paper Pyramid-shaped RC frames are modeled and analyzed. The nonlinear dynamic analysis are carried out applying far-field records of earthquakes. The seismic response of structures are studied and compared with the regular ones. The results specify that the irregularity due to Pyramid shape leads to increase the damage magnitude of RC frames comparing with the regular ones. This increase in taller frames is less than in the shorter ones. Also in wider frames, the effect of irregularity will be decreased.

Pyramid-shape, Vertical irregularity, Damage, far-field records.