A High Order Nonlinear Study to Evaluate the Seismic Response of Rotating Machines–Structure–Soil Foundation Systems

ABSTRACT

Despite the significant advances in finite-element modelling of structures, the soil–structure–equipment interaction is not often accurately accounted due mainly to the nonlinear behaviour of the rotatory equipment. In this paper, different high order nonlinear models are assessed, in order to represent the seismic interaction between the foundation and the rotating machine. Different levels of complexity to represent the response of the equipment and their interaction with the structure are used. A set of 20 artificial ground motion has been considered (horizontal + vertical action), with different frequency contents and peak ground acceleration, to calculate the time–history analysis of the system. The results show that for element’s forces and accelerations, the behaviour of the structures analysed is not very sensitive to the type of modelling chosen. Results also confirmed that it is possible to perform a simplified model of the rotor and their bearings to get a good estimate of the seismic loads applied on the foundation. The displacements on the bearings tend to be underestimated by the simplified models, just like the deformations of the rotor. This can lead to wrong design decisions if inappropriate models are used.

KEYWORDS:

• Rotating Machines
• Soil–Structure–Machine Interaction
• Nonlinear Analysis
• Time History Seismic Analysis

Acknowledgments

The Pontificia Universidad Católica de Chile through the Javier Pinto scholarship has granted financial support to the MsC student during this research. The information on the configuration of the foundations and equipment were obtained from the files on various projects developed in Chile reviewed by EQCO Earthquake Engineering Consultants. The support from all those involved in the project is gratefully acknowledged. The authors would also like to thank the anonymous reviewers for their high professionalism and experience of the topic of rotating machines and seismic analysis that allowed us to improve the original draft of the paper.

Additional information

Funding

This work was supported by the Pontificia Universidad Católica de Chile [Javier Pinto scholarship].