Seismic Analysis of G+20 Story Horizontal Sky Bridge Building and Conventional Building

Abstract

Seismic analysis of adjacent buildings linked through Horizontal sky bridges using ETABS 2021.This project aims to carry out the Seismic analysis of adjacent buildings connected at different levels with Horizontal sky bridges. The study assesses selected alternatives by changing the position of Horizontal sky bridges at three sections in height, mid-height (1/2), three quarter-height (3/4), and the top of the buildings. Both static and dynamic earthquake loading cases are imposed, based on the seismic codes, to evaluate inter-story drift, base shear and joint displacements. Buildings with and without sky bridges are compared to measure the effect of Horizontal sky bridges. The study reveals the effectiveness of Horizontal sky bridges on improving the seismic behaviour by judiciously locating Horizontal sky bridges as Lateral displacement and storey drift are typically reduced when Horizontal sky bridges are included.

Introduction

The growing global population and urban migration have increased the demand for living and working spaces, leading cities with limited land and rising property prices to adopt vertical development through high-rises. Modern skyscrapers represent not only space efficiency but also advancements in structural engineering, architecture, and urban planning, emphasizing sustainable urban living.

A key trend in high-rise design is the use of sky bridges, which connect tall buildings to enhance pedestrian movement, safety, usability, and aesthetics. These bridges reduce elevator use, offer emergency evacuation routes, and alleviate ground-level congestion, noise, and pollution. Structurally, they can be made from struts, reinforced concrete, or steel frames. Notable examples include:

• Petronas Twin Towers (Malaysia) – the sky bridge is vital for fire safety and design.

• Sands Sky Park (Singapore) – a truss-supported, boat-shaped structure connecting three towers over 340 meters.

• Shanghai World Financial Center (China) – the sky bridge enhances both structural integrity and visual identity.

Numerical Study

The study analyzed the seismic performance of two 20-story buildings (61.5 meters high) connected by an RCC sky bridge using ETABS 21 software in Seismic Zone IV. The bridge was modeled at three levels: half the building height (1/2H), three-fourths (3/4H), and full height (H). Two methods were applied for seismic analysis:

• Static Equivalent Method

• Response Spectrum Method

These analyses evaluate the structural response and effectiveness of sky bridge placement under seismic conditions.

Conclusion

From results of the seismic analysis of two buildings connected by a skybridge, utilizing both the Static Equivalent Method and the Response Spectrum Method in ETABS software. The analysis focused on comparing the seismic performance of buildings with and without a skybridge connection, as well as evaluating the effectiveness of horizontal. A. Impact on Base Shear • The addition of skybridges generally increases the base shear of the connected buildings compared to standalone structures. B. Effect on Maximum Story Displacement • Skybridges are generally effective in reducing the maximum story displacement • while a horizontal skybridge (SCB H15) shows reductions, such as 14.36% in EQX and 14.81% in RSX, with slight increases in EQY and RSY. C. Effect on Story Drift: • At floor where building is connected by horizontal sky bridge drift is decease than other floor in direction of sky bridge while in across direction slight increase. • In 20 floor building connecting by one sky bridge horizontal at 15th floor story drift of building is decreasing 30.46% in the direction of the bridge with slight increases in EQY and RSY. Among the different configurations studied, the sky bridge located at 15th floor (SCB H15) is identified as the optimal location for the sky bridge based on the significant reductions observed in both maximum story displacement and story drift in the direction of the bridge.

References

[1] IS 1893:2016 (Part-1) Criteria for earthquake-resistant design of structures. [2] IS 875:2015 (Part-3) Design Loads (other than Earthquake) for Buildings and Structures-code practice [3] IS 456:2000, Plain and Reinforced Concrete – Code of Practice, Bureau of Indian Standards, New Delhi, India. [4] Nisarg Patoliya, Indrajit N., Agrawal, Vimlesh V., \"Seismic Analysis of Tall Buildings Connected with Sky Bridge\", International Advanced Research Journal in Science, Engineering and Technology, 2023. 10.17148/IARJSET.2023.10446 [5] Nahid Islam Romel, Md. Mohiuddin Ahmed, Quazi Reduanul Bari, Badhan Chakma, \"Optimum Location Determination of a Horizontally Connected Steel Bridge for a G+10 Storied RCC Building Under Lateral Loads\", School of Applied Sciences & Technology, SUST, Sylhet, January 2023. [6] Kiran M.U, Shivananda S.M, Mahantesha O., \"A Study of Lateral Drift Controlling Between Two Buildings by Connecting Sky Bridge\", International Journal of Civil and Structural Engineering Research, 2016. [7] Chandan Ahir, Neeraj Singh Bais. \"Research on the Effect of Horizontal Walkway Location Connecting Two High-Rise Buildings (G+20) Under Seismic Loading,\" International Research Journal of Engineering and Technology (IRJET),2024 [8] D.C.P. Ng, M.P Anwar, T.L. Lau, W. Elleithy, A.A. Mohammed, J. Jayaprakash, \"Dynamic Response Analysis of Skybridge Connected Reinforced Concrete Buildings under Lateral Loads\", International Journal of Civil Engineering and Technology,2024.DOI 10.1063/5.0180660

Copyright

Copyright © 2025 Hemanshukumar A. 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.