Low-tech Shake Table

Requested Research

  • Main request. A concept for a simple version of a double-axis shake table, that allows for initial testing of alternative construction techniques and to give a better understanding of their seismic behavior.
  • It should be large enough for full-scale tests of actual sized constructions. Easy to build, easy to handle, easy to maintain.
  • A literature research and overview of all different concepts of seismic testing equipment and shake tables that are currently available.
  • Simplified descriptions of the working of the main testing techniques.
  • An analysis of the reliability and relevance of shake table tests on scale models, compared to full-scale structures.

Status of Research

Open for students and professionals of Structural Engineering, Earthquake Engineering and Mechanical Engineering. We will try to connect students of these different disciplines so they can work jointly on the assignment. Send us an email to request the full assignment sheet via this link.

Past and current research:
2014 – 2015: Group of students from Oregon State University
2015 – 2016: Jazmine Brown, University of San Francisco

Background: The need for a simple shake table

There are many types of shake tables already in use worldwide. Some are small and simple, some can move in only one direction, some in both. Others are fully dynamic and can simulate actual past earthquake patterns, totally computerized.

There are tables that can just test a single wall, a corner section or a scaled model, while the largest table can test a full-scale model of a seven storey building. Most tests are accurate, but also time consuming and very costly.

Time and money presumably are the main reasons why most alternative construction techniques have not been tested up to today. Organizations or entrepreneurs cannot bear the high cost and long time it takes to carry out a full seismic test.

So perhaps we can come up with an in-between concept? A series of preliminary tests that gives us an initial idea of how certain techniques will likely behave during an earthquake. A simplified installation that can carry out basic tests in terms of overall seismic behavior, in- and out of plane failure, tension patterns and such. This in order to answer an interesting first question: Do we rule out the technique, or is it promising enough for further testing?

Background: Scaled Models versus Full-size Testing

For testing larger or full-scale structures, of course we will need a bigger shake table. Therefore we see many cases where scaled models are built and tested. The question is, how reliable is this?

Will the strength of a 25% scaled model be equal to 25% of full-sized strength? Do lesser-dimensioned materials (wooden members, bricks, steel reinforcements) have comparable strength in a scale model, as compared with full-sized elements within a full structure? Are connections in a scale-model as strong as in a real corner or T-section? Must we subject the model to a lesser equivalent of movement and shaking?

Or more simply said; will a scaled house react the same when subjected to seismic forces as a full-sized house would do?

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