Seismic Performance of Irregular Reinforced Concrete Building Frame

A structure is considered irregular if it exhibits uneven mass, stiffness, and strength distributions or has an irregular shape. Most structures exhibit irregularity for functional and aesthetic reasons. One significant reason for a structure’s collapse during past earthquakes is the irregular configuration of the structure, either in its plan or elevation, as a building’s performance during a seismic event is largely determined by its configuration. Therefore, Irregular structures in areas with high seismic activity raise significant concerns. Structures may have one or more types of structural irregularities. Selecting the type, placement, and extent of irregularities is vital in structural design. According to IS Code 1893 (Part 1): 2016, it is advisable to minimize irregularities by updating architectural designs and structural layouts. However, the concept of “perfect regularity” is an idealized representation., as real structures inevitably contain irregularities due to various needs and demands, and these irregularities are a significant part of modern urban infrastructure. Hence, structural irregularities have become inevitable, and this study aims to analyse their performance. A G+9 storey regular (Square-Shaped) RCC frame building is developed, and two L-shaped models with plan asymmetric and two setback models with vertical geometric irregularities were created by reducing a specific percentage from the regular (square-shaped) reference model. All models are subjected to earthquake loading, and their responses are computed using CSI ETABS software. The objective will be achieved by comparing the responses of the various models through Response Spectrum Analysis.