Parametric Study on the Effect of Outrigger Location at Different Stories in High Rise Structure

Abstract

Outrigger optimization is a significant challenge. The objective of this paper is to give a better understanding of outrigger location optimization and the efficiency of each outrigger when several outriggers are used in the structure. Results revealed that the inclusion of multiple outriggers significantly improved structural performance, particularly when positioned at strategic levels, typically at 0.25H, 0.5H, and 0.75H of the building height. The most effective configuration under and seismic conditions was a triple outrigger system placed at these levels.

Introduction

Urbanization drives population concentration in cities, increasing the demand for vertical construction due to limited and expensive land. This leads to the rise of tall skyscrapers, which require advanced structural engineering to withstand lateral loads. One effective structural system for tall buildings is the Core and Outrigger system, where the building’s central core is connected to outer columns via horizontal outrigger trusses. These help resist rotation and lateral forces. The system’s effectiveness depends on factors like stiffness, positioning, building geometry, and number of outriggers.

In the study, a 36-story symmetrical building (30m x 30m plan, 3m floor height) is analyzed under seismic zone V conditions with soil type II. Key structural responses such as story displacement, base shear, and time periods are evaluated to assess performance.

Conclusion

Based on the observations and the results obtained during this study, we can arrive at the following conclusions: 1) The use of outrigger system in high rise structure increases the stiffness and makes the structure more efficient under seismic. 2) It can be concluded from this study that the outrigger system provides reduction in displacement, drift and base moment and time period. 3) As the height of building increases then necessity of new structural system arises Outrigger structural system depends on number and its position throughout the height of the building. 4) The best performing model for dynamic assessment subjected to earthquake and wind load cases in a 36-storey Building when outrigger places at 0.25H, 0.5H, 0.75H. 5) Outrigger performs well compared to rigid frame and core system.

References

[1] IS 1893 (Part 1): 2016 Criteria for Earthquake Resistant Design of Structures, Part 1: General Provisions and Buildings. [2] IS 456 (2000): Plain and Reinforced Concrete. [3] IS 16700:2023 Criteria for Structural Safety of Tall Concrete Buildings [4] Chambulwar, S., Kadam, T. S., Bhujbal, A. M., Konde, P. P., & Alandkar, S. B. (2021). Comparative study of RCC frame structure with and without outrigger system. International Journal of Research in Engineering and Science (IJRES), 9(6), 45–47. Retrieved from http://www.ijres.org [5] Sundar, R. S., & Gore, N. G. (2017). A study on tall RC structure with outrigger system subjected to seismic and wind loading. International Journal of Engineering Research & Technology (IJERT), 6(2), 515–520. http://www.ijert.org [6] Choi, H. S., Ho, G., Joseph, L., & Mathias, N. (2012). Outrigger design for high-rise buildings: An output of the CTBUH Outrigger Working Group. Council on Tall Buildings and Urban Habitat. Published by Routledge, Taylor & Francis Group. [7] Das, B. B., Barbhuiya, S., Gupta, R., & Saha, P. (Eds.). (2021). Recent developments in sustainable infrastructure: Select proceedings of ICRDSI 2019 (Vol. 75). Springer. https://doi.org/10.1007/978-981-15-4577-1\\

Copyright

Copyright © 2025 Kevin Patel, Dr. V. R. Patel. 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.