Comparative Analysis on Symmetric and Asymmetric Structure Subjected to Seismic Load - Using ETAB

Abstract

Earthquakes can badly affect buildings, especially in places where earthquakes occur often. How a building reacts during an earthquake depends on its shape, weight distribution, and strength. In this study, symmetric and asymmetric buildings were compared using ETABS software to understand how theybehave during earthquake conditions. Different building shapes such as rectangular, L-shaped, and T-shaped buildings were analysed. Important factors like storey displacement, storey drift, base shear, and twisting effects were studied. The results showed that symmetric buildings perform better during earthquakes because the earthquake forces get distributed evenly throughout the structure. On the other hand, asymmetric buildings experience more movement and twisting due to their irregular shape and uneven stiffness. This study shows the importance of proper building planning and structural design for earthquake safety. It also explains how ETABS helps engineers analysebuildings and design safer structure in earthquake- prone.

Introduction

This study investigates the seismic performance of symmetric and asymmetric RCC framed buildings using ETABS software. RCC buildings are widely used due to their strength and durability, but earthquakes pose a significant threat because of their sudden and destructive nature. The behavior of a building during earthquakes depends on factors such as shape, stiffness, mass distribution, and structural configuration.

Symmetric buildings generally perform better during earthquakes because their mass and stiffness are evenly distributed, resulting in uniform force distribution, lower displacement, reduced storey drift, and minimal torsional effects. In contrast, asymmetric buildings with irregular shapes such as L-shaped and T-shaped structures experience uneven force distribution and twisting (torsion), leading to greater displacement, higher storey drift, and increased stress in structural members.

The study aimed to model and analyze symmetric and asymmetric buildings according to IS 456 and IS 1893 codes, compare key seismic parameters such as displacement, storey drift, and base shear, examine the effects of torsion in irregular structures, and determine which building type provides better earthquake resistance.

Four building models were analyzed: one symmetric rectangular building and three asymmetric buildings with irregular layouts. All models had the same height (G+7 storeys), material properties, and loading conditions, with only the building shape varying. Results showed that the symmetric building exhibited superior seismic performance with lower displacement and drift. The asymmetric models initially experienced excessive displacement, storey drift, torsion, and member failures. Structural improvements such as increasing beam and column sizes, using higher-grade concrete (M30 and M40) and Fe500 steel, adding corner columns, and modifying layouts improved their seismic behavior.

The study concludes that symmetric buildings are safer, more stable, and easier to design for earthquake resistance due to their balanced mass and stiffness distribution. Although asymmetric buildings offer greater architectural flexibility and better space utilization, they are more vulnerable to earthquake damage and require advanced analysis, additional reinforcement, and higher construction costs to achieve adequate seismic performance. Proper planning, strengthening measures, and detailed ETABS analysis are essential for ensuring the safety of irregular structures in earthquake-prone regions.

Conclusion

From the detailed analysis done using ETABS, shape and arrangement of a building greatly affect its behavior during earthquakes. Symmetric structures perform better during earthquakes because their mass and stiffness are evenly distributed. This reduces the twisting effect and helps the buildings respond more safely and evenly to seismic forces as result, symmetric buildings show lower displacement, less story drift and better overall stability. On the other hand, asymmetric structures have irregular shapes and uneven stiffness distribution, which causes more twisting during earthquakes. This leads to higher displacement, uneven stress in structural members, and a greater chance of damage. Therefore,symmetricstructures are generally preferred in earthquake-prone areas because they provide better safety and performance. However, if asymmetric designs are required for architectural or functional reasons, special measures such as shared walls, bracing systems, and proper structural detailing should be used to improve earthquake resistance. Advanced analysis using software like ETABS is also important to accurately study the building’s behavior and ensure a safe and reliable design.

References

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Copyright

Copyright © 2026 Divya D. Powar, Amruta Bhosale, Prachi P. Godhade, Pranali V. Powar, Snehal L. Mane. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.