Implementation of a Novel Inertial Mass System and Comparison to Existing Mass-Rig Systems for Shake Table Experiments

Alvaro Lopez,Peter Dusicka

doi:10.3390/app11020692

Alvaro Lopez, Peter Dusicka

Open Access

https://doi.org/10.3390/app11020692

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Abstract

Shake table testing is one of the more effective experimental approaches used to study and evaluate seismic performance of structures. Reduced-scale models can still result in large-scale specimens where incorporating the required inertial mass effectively and safely can be challenging. This study proposes a new system of arranging the mass in the experiments that combines the realism of mass participation during earthquake excitation when supported by the shake table with laboratory practicality considerations of the mass positioned off the specimen. The characteristics and dynamic motion equations for the proposed system are described and applied to shake table experiments involving large-scale cantilevered columns. Using data from large-scale experiments to validate a numerical model, the proposed approach was numerically compared to two other testing approaches. Based on the measured performance and the validated numerical simulations, it can be concluded that the proposed inertial mass system can result in seismic performance as if the mass was placed directly on top of the specimen. Combined with the advantages of reduced setup time, incorporating safety restraints and direct measurement of inertial loads, the proposed system can be suitably used for effective shake table testing of large-scale specimens taken to non-linear near-collapse performance levels.

Highlights

To diminish the existing vulnerabilities of infrastructure to seismic hazards and fulfill the ever-increasing structural demands of modern codes, the earthquake engineering community has steadily worked over the years to enhance knowledge on the behavior of structures under severe earthquakes
When large-scale models are evaluated using shake tables, large quantities of inertial masses must comply with proper representation requirements in terms of a fundamental period of the prototype structure and practical constraints imposed by the simulator capabilities
Safety issues and cost-effective set up considerations limit its utility especially when considering large test matrices

Summary

Introduction

To diminish the existing vulnerabilities of infrastructure to seismic hazards and fulfill the ever-increasing structural demands of modern codes, the earthquake engineering community has steadily worked over the years to enhance knowledge on the behavior of structures under severe earthquakes. Structural response generated during shake table tests are the most consistent with the actual structural responses that occur during earthquakes These types of experiment have the advantage of reproducing recorded accelerations of real earthquakes with high reliability while maintaining the real dynamic rate characteristics, which include all inertial effects of the test specimen. These realistic conditions are highly useful in validating and calibrating models for seismic design, in performing evaluation of structures and in conducting seismic risk assessment [2,3]

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