Comparative Evaluation of RCC Buildings with Interior and Multi-Level Floating Column Configurations Using STAAD.Pro

Abstract

The presence of floating columns in RCC buildings alters stiffness distribution and affects seismic response. This study evaluates the influence of interior and multi-level floating column arrangements in a G+12 building. Four configurations are analyzed: exterior floating columns at intermediate level (M1), multiple exterior floating columns (M2), interior floating columns at lower levels (M3), and interior floating columns at upper levels (M4). Response spectrum analysis is performed as per IS 1893 (Part 1):2016. Results indicate that interior floating columns produce higher displacement and axial force concentrations compared to exterior configurations. Multi-level floating columns further amplify irregularity. The study identifies critical configurations and emphasizes the importance of stiffness continuity in seismic design.

Introduction

The text discusses the seismic behavior of reinforced cement concrete (RCC) buildings with floating columns. Floating columns are vertical structural elements that rest on beams or slabs instead of directly transferring loads to the foundation. They are commonly used in high-rise and commercial buildings because they allow large open spaces and greater architectural flexibility. However, floating columns create discontinuities in load transfer, making structures more vulnerable during earthquakes.

The study focuses on the seismic vulnerability caused by vertical irregularities such as floating columns, soft storeys, setbacks, and transfer girders. These irregularities disturb the uniform distribution of seismic forces and negatively affect the building’s dynamic response during earthquakes.

To improve seismic safety, the paper emphasizes the importance of the Strong-Column Weak-Beam (SCWB) concept. This seismic design philosophy ensures that columns remain stronger than beams so that, during severe earthquakes, beams form plastic hinges and absorb energy while columns remain stable. In buildings with floating columns, this principle becomes especially important because force redistribution increases the seismic demand on columns. Failure of columns can lead to storey collapse or global structural instability.

The study compares the seismic response of buildings with:

• Interior floating columns versus exterior floating columns
• Multiple floating column levels
• Different floating column arrangements

For the analysis, a G+12 RCC moment-resisting frame building was modeled using STAAD.Pro software. The building has a rectangular plan, fixed supports, and is located in Seismic Zone III. A linear elastic dynamic analysis using the Response Spectrum Method was performed.

Four structural models were analyzed:

1. Model 1 (M1): Exterior floating columns at the 3rd storey.
2. Model 2 (M2): Exterior floating columns at multiple levels (2nd, 3rd, 10th, and 11th storeys).
3. Model 3 (M3): Interior floating columns at the ground and first floors.
4. Model 4 (M4): Interior floating columns at the 4th, 5th, and 12th storeys.

The study included dead loads, live loads, earthquake loads, and wind loads applied in both X and Z directions according to Indian Standard codes. The research aims to evaluate how different floating column configurations influence seismic performance, structural stability, and load redistribution in RCC buildings.

Conclusion

The study clearly establishes that floating columns significantly influence force transfer mechanisms, stiffness distribution, and seismic performance of multistorey RCC buildings. • Interior floating columns are more critical than exterior ones • Multiple floating column levels increase seismic vulnerability • Lower storey floating columns create soft-storey effect • Transfer beams supporting floating columns are the governing elements for bending and shear design. • M3 is the most critical configuration

References

[1] Bureau of Indian Standards (2000). IS 456: Plain and Reinforced Concrete – Code of Practice. New Delhi, India. [2] Bureau of Indian Standards (2016). IS 1893 (Part 1): Criteria for Earthquake Resistant Design of Structures. New Delhi, India. [3] Bureau of Indian Standards (2016). IS 13920: Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces. New Delhi, India. [4] Bureau of Indian Standards (1987). IS 875 (Part 1 & 2): Dead Loads and Live Loads. New Delhi, India. [5] Bureau of Indian Standards (2015). IS 875 (Part 3): Wind Loads. New Delhi, India. [6] Anil K. Chopra (2012). Dynamics of Structures: Theory and Applications to Earthquake Engineering. Pearson Education. [7] Pankaj Agarwal & Manish Shrikhande (2010). Earthquake Resistant Design of Structures. PHI Learning. [8] S. K. Duggal (2010). Earthquake Resistant Design of Structures. Oxford University Press. [9] T. Paulay & M. J. N. Priestley (1992). Seismic Design of Reinforced Concrete and Masonry Buildings. Wiley. [10] C. V. R. Murty (2005). Earthquake Tips Learning Earthquake Design and Construction. IIT Kanpur. [11] Rajkumar, B., & Meera, K. (2015). Seismic behavior of buildings with floating columns. International Journal of Civil Engineering Research, 6(2), 45–52. [12] Gupta, A., & Gajbhiye, P. (2014). Seismic analysis of RCC buildings with floating columns. International Journal of Engineering Research, 3(4), 214–219. [13] Malviya, R., & Patil, S. (2014). Effect of floating columns on structural response. International Journal of Structural Engineering, 5(3), 120–126. [14] Kamble, P., & Mali, K. (2015). Comparative study of interior and exterior floating columns. IJERT, 4(6), 890–894. [15] Joshi, S. D., & Tande, S. N. (2014). Performance evaluation of RCC frames with floating columns. IOSR Journal of Mechanical and Civil Engineering, 11(2), 01–06. [16] Waykule, R., et al. (2015). Comparative seismic performance of buildings with floating columns. International Journal of Innovative Research, 4(5), 325–330. [17] Sekhar, T. R., & Prasad, P. V. (2013). Seismic response of buildings with floating columns. International Journal of Engineering Trends, 2(3), 101–106. [18] Sabari, S., & Praveen, J. V. (2016). Effect of stiffness irregularity in floating column buildings. IJCIET, 7(4), 234–240. [19] Rao, B. S., et al. (2020). SCWB evaluation in RCC buildings with floating columns. Engineering Structures, 210, 110–118. [20] Patel, R., & Desai, A. (2017). Response spectrum analysis of floating column buildings. International Journal of Civil Engineering, 8(2), 55–62. [21] Soni, D. P., & Mistry, B. B. (2018). Dynamic analysis of buildings with floating columns. Procedia Engineering, 173, 151–158. [22] Patil, N. A., & Shah, R. S. (2016). Comparative study of RCC buildings using ETABS. International Journal of Engineering Science, 7(1), 89–95. [23] Behera, S., et al. (2019). Effect of stiffness on floating column buildings. Asian Journal of Civil Engineering, 20(3), 345–356. [24] Shrikanth, M. K., et al. (2018). Seismic response of high-rise buildings with floating columns. International Journal of Structural Stability, 18(2), 185–196. [25] Bhensdadia, H., & Shah, S. (2017). Pushover analysis of buildings with floating columns. International Journal of Advanced Structural Engineering, 9(1), 45–52. [26] Mondal, A., & Chakrabarti, A. (2013). Behaviour of irregular buildings under seismic loading. Journal of Structural Engineering, 40(5), 500–507. [27] Kaushik, H. B., & Jain, S. K. (2016). Seismic performance of irregular RC buildings. Earthquake Engineering Review, 12(2), 75–84. [28] Roy, R., & Chakrabarti, A. (2014). Effect of vertical irregularity on seismic response. International Journal of Engineering Research, 3(6), 400–406.

Copyright

Copyright © 2026 Miss. Shravasti Tijare, Dr. A. R. Gupta, Prof. Ms. A. H. Deshmukh. 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.