Optimized Sandwich Deck Foundation Design for Turbo Generators under Seismic Loading

Abstract

This paper presents a novel approach to designing and optimizing a turbo generator deck foundation using a sandwich structural concept. The foundation consists of two reinforced concrete slabs separated by a damping material layer, aiming to enhance vibration mitigation while reducing material usage and construction costs. Finite Element Modelling (FEM) and dynamic analysis are used to evaluate the performance of the design under operational and fault-induced dynamic loads. Modal and harmonic analyses show that the proposed sandwich design significantly reduces vibration amplitudes and shifts resonance frequencies away from critical operating ranges. The results suggest that the optimized foundation design provides better structural performance compared to traditional monolithic decks, supporting the development of more efficient and sustainable industrial foundation systems.

Introduction

Turbo generator foundations require high structural integrity and dynamic stability, but traditional monolithic concrete designs often fall short in vibration control and material efficiency. This study proposes a sandwich-type foundation with two concrete slabs separated by a damping layer to enhance vibration damping and reduce material use.

Methodology involved using Finite Element Analysis (ANSYS) to model the dynamic behavior under normal and fault conditions. The damping layer, made from viscoelastic materials, was tested in various thicknesses.

Key Findings:

• The sandwich design increased natural frequency separation from the generator’s operational frequency (50 Hz), reducing resonance risks.

• Peak vibration displacement decreased by up to 40% with optimal damping.

• A 75 mm damping layer with a 0.6 loss factor offered the best performance-cost balance.

• Compared to traditional foundations, the new design reduced structural mass by ~15% and construction costs by ~10%.

Conclusion

This research demonstrates the feasibility and advantages of using a sandwich structure for turbo generator deck foundations. By incorporating a viscoelastic damping layer between concrete slabs, the design effectively reduces dynamic responses and improves operational stability. Finite Element Analysis confirms that such foundations can outperform traditional monolithic designs in terms of vibration control, material efficiency, and cost-effectiveness.Future work should focus on experimental validation of the simulation results and the development of full-scale prototypes. Additionally, the applicability of this design approach to other types of rotating machinery foundations and dynamic systems should be explored.

References

[1] Journal of Sound and Vibration 1986, “a procedure for balancing large turbo generator sets Via a finite element model” 2. [2] P.St. Fleischer and P.G. Trombik, World Conference on Earthquake Engineering Journal 2008, “Turbo Generator Machine Foundations Subjected to Earthquake Loadings” 3. [3] P. Jiang, Modal Analysis for Steam Turbine/Generator Machine Table-Top Foundation, Structures Congress ASCE, 2010 4. [4] J. Liu, Design of Foundations for Large Dynamic Equipment in a High Seismic Region, Structures Congress”,Published by American Society of Civil Engineers, (2013) 5. [5] Jyoti K. Sinha1, W. Hahn, K. Elbhbah, Kelechi G. Obi-Mgbam, Measurement 2016, “Vibration of a Steam Turbo-Generator (TG) Set during Shutdown Period” 6. [6] Mohamed A. El-Reedy, Onshore Structural Design Calculations 2017, “ Design of a Foundation Under Vibrating Equipment”

Copyright

Copyright © 2025 Dr. S. S. Anglekar, Mr. Niwant R. Pawar. 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.