The behaviour of G+9 space frame building of regular and irregular configuration under earthquake is complex and to act as simultaneously with earthquake loads. In this paper an industrial G+9 space frame building is studied for earthquake using STAAD-PRO V8I. The behaviour of building ability to dissipate energy and effect of the lateral deformation. This paper is concerned with the effects of two type irregularities on this seismic response of a structure. Lower stiffness results in higher displacements of upper stories. Tall structures were found to have lower natural frequency hence their response was found to be maximum in a lower frequency earthquake. It is because low natural frequency of tall structures subjected to low frequency earthquake leads to resonance resulting in large displacements earthquake engineering is to design and build a structure in such a way that the damage to the structure and its structural component during an earthquake is minimized. The component of the building, which resists the seismic force, is known as lateral force resisting system. The damage in a structure generally initiates at location of the structural weak planes present in the building system. The weaknesses obtained occur due to presence of the structural irregularities in stiffness, strength and mass in a building system. The structural irregularity can be broadly classified as plan and vertical irregularities. The maximum deflection produced in the structure, weight of steel required by the structure and percentage of failed member has been considered as measured. Optimization is a process of subjecting all members present in the structure to minimum usage thereby ensuring the utilization ratio of each and every element more than 80%. It is to be noted that the structural properties not be compromised.
