Stability Assessment of Reinforced Concrete Building Using Outrigger and Truss Belt System

Abstract

For the study, we have considered ten test models, out of which one model is not having shear wall. This model is called bare frame. From the bare frame model other nine test models with shear wall is compared in order to define the optimum location of shear wall for L shaped building. Dynamic Analysis is done for the comparative study of the models. We have used standard software package of CSI ETABS ver. 16.0.0 for the modeling and analysis of the structure. Under dynamic analysis, we have limited ourselves to RSA & THA Both of these analyses are done under elastic limit. For Response Spectrum Method, we have considered the graph for Seismic Zone V with medium soil for a damping ration of 5% and importance factor as ‘1’. The RS Analysis has been carried out according to IS 1893 (Part-1):2016 by using CSI ETABS ver. 16.0.0. For Time History Analysis, we have used the time history data of Array Recording Station, El Centro, USA. The data is under the software package. We have determined the suitable configuration of shear wall in building, on various ground of comparison which is defined in the thesis.

Introduction

The text discusses the structural design challenges of high-rise reinforced concrete (RC) buildings, defined in India as structures with a height of 22.5 m or more. Unlike low-rise buildings, high-rise structures must account for additional loads such as wind and earthquake forces, making their design more complex and critical. Irregular building shapes, structural discontinuities, and eccentricity further affect performance by increasing stresses and deflections, requiring advanced analysis and strengthening techniques such as retrofitting.

A key focus of the study is seismic performance, as earthquakes pose severe risks to life, infrastructure, and essential services. Modern RC framed buildings, while efficient in load transfer through beams and columns, often lack sufficient lateral stiffness since walls are not load-bearing. To address this, the study explores the outrigger and belt truss system, a lateral load-resisting mechanism that connects the central core (shear walls) to perimeter columns, significantly reducing overturning moments and lateral displacement. This system enhances stiffness, reduces drift, and improves occupant comfort during wind and seismic events, especially in tall and slender buildings.

The objectives of the study include comparing lateral displacements, storey shear, base force, and overturning moments between conventional bare-frame models and models equipped with outrigger and belt truss systems under seismic loading using the Response Spectrum Analysis (RSA) method.

The methodology involves modeling and analysis using ETABS software, applying Indian seismic codes (IS 1893:2016) for Zone V conditions. Various structural parameters such as material properties, geometry, loading, and soil conditions are defined to evaluate performance.

Results indicate that buildings with outrigger and belt truss systems show reduced storey displacement and improved seismic stability compared to conventional frames. Overall, the study concludes that outrigger beams with belt truss systems are effective and suitable for enhancing the seismic performance and stability of high-rise RC structures.

Conclusion

The different arrangement of outrigger are beneficial to reduce bending moment. it is found that implementation of outrigger with truss belt system is one of the important factor of earthquake design. From the test models, M-4 {Structure with outrigger beams with truss belt system} was considered as the model with optimum usage of outrigger. The optimum usage of outrigger is based on minimum story displacement, also lesser values of story drift. The dimensions of structural members are considered the same for both the structures, the effectiveness of Outriggers-Belt truss structures posed substantial resistance against the load conditions. The Outriggers belt truss system resisted the gravity loads without any interior columns, thus making the structure economical and cost-efficient. The Outrigger-Belt truss system strongly supports the earthquake design philosophy of Strong Column and Weak Beam which maximizes the efficiency of the structure.

References

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Copyright

Copyright © 2025 Sushant Singh Bhadoria , Ms. Chaitali Gangwal , Dr. Chaitanya Mishra. 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.