PSI - Issue 70

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ScienceDirect

Procedia Structural Integrity 70 (2025) 604–610

Structural Integrity and Interactions of Materials in Civil Engineering Structures (SIIMCES-2025) Effect of Floor Area Ratio Reduction on the Fundamental Period of RC Buildings on Flat and Sloped Terrains Arijit Banik a, *, Tusar Chakma a , Prakash Debbarma a , Biplab Das a , Roveto Sapu a , Joydeep Nath a , Souradeep Deb a , Bikash Tripura a a Department of Civil Engineering, Tripura Institute of Technology, Narsingarh, Agartala, Tripura (West), 799009, India Abstract Structural irregularities, common in reinforced concrete (RC) buildings on sloped terrain and compounded by setbacks, make them highly susceptible to seismic damage. This study specifically examined how the floor area ratio (FAR)influences the fundamental time period of such structures. Numerical analyses are conducted on RC buildings with fixed supports, considering both flat (0 degree slope) and hilly (35-degree slope) terrains. A direct comparison between regular buildings (FAR = 1.0) and setback buildings (FAR = 0.5) showed a significant average reduction in the fundamental time period: 15.04% for flat terrain models and 15.83% for hilly terrain models. These results suggest that vertical irregularities play a pivotal role in a building's seismic response, underlining the need for advanced empirical models to improve seismic performance predictions and structural design practices for RC buildings with setbacks. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of International Conference on Structural Integrity Organizers

Keywords: Fundamental Period; Sloping Terrain; Reinforced Concrete Buildings; Setback Buildings.

1. Introduction The seismic performance of reinforced concrete (RC) buildings has been widely explored, especially because of their extensive use in regions prone to earthquakes. However, buildings constructed on sloped terrains often present unique challenges that deserve special attention. These structures tend to show irregularities in their form and structural behavior due to differences in foundation levels, which create uneven distributions of mass and stiffness. As a result,

* Corresponding author. Tel.: +91-9774138208. E-mail address: arijit.banik07@gmail.com

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of International Conference on Structural Integrity Organizers 10.1016/j.prostr.2025.07.096