Overview of the hybrid shake table configuration.

San Diego — Hybrid simulations involving experimental substructures on the largest shake table in the U.S. were successfully completed through the collaborative effort of hybrid simulation experts from the Natural Hazards Engineering Research Infrastructure (NHERI) SimCenter and UC San Diego Experimental Facility. These tests were executed during the commissioning of hybrid simulation capabilities at UC San Diego.

The real-time hybrid shake table testing involved the numerical simulation of multi-story shear buildings subjected to earthquake loading with the upper story of the hybrid model being tested experimentally and excited by the Large High Performance Outdoor Shake Table (LHPOST) at UC San Diego. Hybrid shake table testing provides an efficient approach for performing parameter studies, by changing the properties and the behavior of the numerical portion of the hybrid model from test to test. The data produced in these experiments is being curated on the NHERI DesignSafe Data Depot.

The development team included research engineer Andreas Schellenberg from the NHERI SimCenter; and professor Gilberto Mosqueda, postdoctoral researcher Humberto Caudana, graduate student Manuel Vega, and Site Operations Manager Darren McKay from UC San Diego.

As part of the development and commissioning effort, computational expertise and software components from the SimCenter were implemented to extend the capabilities of the UC San Diego EF to enable real-time hybrid shake table testing.

The hybrid models consisted of buildings where the upper story (or tuned-mass-damper) was experimentally tested on the shake table and the lower stories were modeled numerically in Simulink or OpenSees. The experimental setup consisted of a rigid mass supported on four triple pendulum bearings. Two and six degree-of-freedom building structures were examined to verify the stability of the system in the presence of higher frequency modes. The experimentally tested portion of the hybrid model can represent the upper stories of a building isolated by a mid-level isolation system or a tuned mass damper on top of a building. The demonstrated testing capabilities will now enable researchers to investigate different hybrid simulation configurations that take advantage of the large capacity of the shake table and the available soil boxes to include geotechnical elements.

The SimCenter’s Andreas Schellenberg noted, “We were pleased to bring our expertise and experience to expand the shake table capabilities to include hybrid testing. The collaboration with UC San Diego was fruitful and mutually beneficial, as demonstrated by the successful implementation and verification of two approaches for performing hybrid shake table tests. We’re excited to see what NHERI researchers accomplish with this new capability.”

“Through the collaboration with the SimCenter, we were able to implement new hybrid testing capabilities including advanced computational modeling that will allow for the integration of more complex numerical models. We look forward to working with researchers seeking to implement hybrid testing on the LHPOST,” said Gilberto Mosqueda of UC San Diego.

The NHERI Computational Modeling and Simulation Center (SimCenter) provides researchers access to next-generation computational modeling and simulation software tools, user support, and educational materials needed to advance the capability to simulate the impact of natural hazards on structures, lifelines and communities. The SimCenter’s cyberinfrastructure framework will allow collaborative simulations from various disciplines to be integrated, while accounting for all pertinent sources of uncertainty. More information about the NHERI SimCenter can be found at https://simcenter.designsafe-ci.org.

The NHERI UC San Diego Experimental Facility provides a large, high-performance, outdoor shake table (LHPOST) to support research in structural and geotechnical earthquake engineering. The facility enables research with extensively instrumented large- or full-scale structural, geotechnical, and soil-foundation-structural systems tested under extreme earthquake loads, to produce the experimental data essential to advancing predictive seismic performance tools.

Research experiments performed using LHPOST provide life-size investigations that transform the practice of earthquake engineering and educate graduate, undergraduate, and K-12 students, as well as the general public, about natural disasters and the national need to develop effective technologies and policies to prevent these natural hazard events from becoming societal disasters. More information about the NHERI UC San Diego EF can be found at https://ucsd.designsafe-ci.org.