Comparison of the Effects of Structural System Irregularities on Structures

Abstract

This study examines and compares the conditions of different structures obtained as a result of research on irregularities in structural systems. Investigations conducted after a damaging earthquake revealed that many of the collapsed buildings had excessive eccentricity between their center of rigidity and center of mass, and that the structural system was subjected to second-order moment effects due to the resulting torsional irregularity. The author's investigations revealed that the torsional irregularity is caused not by column or shear wall design, but rather by loads that are assumed to be uniformly distributed but are actually uneven, and by infill walls. Changes in the intended use of existing buildings (such as enlarging rooms in apartments or expanding spaces used as shops) lead to increased inter-story displacements and torsional irregularities.