BEHAVIOUR OF ARCHITECTURALLY IRREGULAR BUILDING

Abstract

Architecturally Irregular buildings like setback buildings are characterized by staggered abrupt reductions in floor area along the height of the building, with consequent drops in mass, strength and stiffness. Height-wise changes in stiffness and mass render the dynamic characteristics of these buildings different from the ‘regular’ building. The increasing number of damage after seismic ground motion has provided strong evidence that setback buildings exhibit inadequate behavior though they were designed according to the current seismic codes. Many investigations have been performed to understand the behavior of irregular structures as well as setback structures and to ascertain method of improving their performance. So, there is a need to study the seismic performance of setback structures designed by recent codes the adequacy of current seismic design requirements for setback buildings, and new design methods to improve the seismic response of setback buildings. It is possible to evaluate the seismic performance of setback building accurately using STAAD. Pro. Software. It is instructive to study the performance of static equivalent analysis methodology as well as other alternative methodologies for setback buildings and to suggest improvements suitable for setback buildings. After study all models in details it is concluded that consideration of the revised seismic codes provisions for geometric vertical irregularities seems to be essential to stipulate more restrictive limits or apply more accurate analytical procedures to predict the seismic performance of setback structures under the seismic excitations, especially for structures with critical setback ratios.