Resizing columns in typical eccentric and torsionally irregular multi-storied buildings

Structures with asymmetric plans, disproportionate strength, and unequal mass distribution exhibit undesirable behavior during severe ground motion and initiate a collapse mechanism. The eccentricity in a building is a major factor that influences this behavior. To reduce eccentricity popular practices, such as steel braces, shear walls, seismic isolation, and haunches might not be viable in different scenarios due to technical, financial, functional or architectural requirements. This paper discusses a more convenient and economical method of resizing the columns to mitigate the eccentricity and torsion. The viability of this method is assessed by iterating with different sizes of columns in two building models and evaluating the corresponding eccentricity changes. The sum of findings highlights that resizing the columns is very effective for buildings with initially smaller-sized columns (generally low-to-mid-rise buildings). However, the effectiveness of this method decreases as the column size increases. To compare the efficacy of column resizing technique, analysis of structures with diagonal steel bracing system has been carried out. The analysis showed that the bracing system improved the performance of buildings in terms of eccentricity and torsional irregularity; however, the cost of adding a bracing system would be much higher than the resizing technique.