Unprecedented laminar floor box system demonstrates cutting-edge design and engineering expertise

The new large-scale laminar floor box system is the latest addition to the University of Nevada, Reno’s world-renowned seismic engineering complex. It is the largest such facility in the United States and comparable in size to the largest in the world. Factor in its unprecedented level of flexibility, and the Soil Box system is truly a one-of-a-kind experimental facility and a model of technical innovation.

When it came to designing and building this massive and versatile facility, there was no need to look far for engineering know-how and experience. Foundation Professor Ian Buckle, from the University’s Center for Earthquake Research in Civil Engineering (CCEER) and Principal Investigator of the Floor Box Project, joined Associate Professors Patrick Laplace and Sherif Elfass of research and responsible for the design of the project. After all, Laplace had designed the University’s triaxial shake table, also called a 6-DOF table, and Elfass had designed two other floor boxes for shake table testing.

“This team has outstanding experience and knowledge in designing and manufacturing a one-of-a-kind experimental facility.”

“This team has outstanding experience and knowledge in designing and manufacturing a one-of-a-kind experimental facility. Their track record of successfully building unique experimental systems was key to turning to UNR for system design,” said David McCallen, project manager for the sponsor and director of CCEER.

The Soil Box system will provide important data to advance earthquake simulation and allow assessment of the complex way structural systems such as buildings and bridges interact with the surrounding soil during the event. Its design and construction were supported by the US Department of Energy (DOE). The project was started in 2015 to protect DOE buildings that contain sensitive scientific instruments from potential earthquake scenarios.

James McConnell, Associate Principal Deputy Administrator of the DOE’s National Nuclear Security Administration, said: “It is important that the DOE and the NNSA invest in this work to ensure that the large, complex and unique facilities we are building are designed to protect the the country’s research, defense and power generation needs, but the results have the added benefit of helping engineers and architects in industry and the private sector build a wide range of weather-resistant structures. earthquake.

The 15-foot-tall, 21.5-foot-wide floor box rests on a 24-foot square tray or platform that can be shaken by sixteen hydraulic actuators used to generate horizontal motions as in a earthquake. earth. The floor box has 19 layers, called laminates, which are each supported by custom elastomer (rubber) bearings so that the floor layers can move relative to each other as they do in real earthquakes . To create seismic movements in the laboratory, the system can move and accelerate up to 350 tons of soil in two horizontal directions simultaneously with the same force as a strong earthquake, and is so powerful that designers had to incorporate controls protection to ensure the system could not get damaged during the experiments. The hydraulics of the system are controlled by custom software and the box is equipped with a suite of sensors to collect detailed data sets under carefully controlled prescribed seismic motions.

“There are very few organizations or companies with the knowledge and expertise to do this, so we decided to do it ourselves with our own expertise and resources,” Buckle said. “This design not only allows us to work with large-scale structural models that can be embedded in soil, but also the size of the box allows for more realistic soil properties to be modeled.”

Laplace, who designed much of the shake table system, including the platter, hydraulics, actuators, reaction buttresses and electrical control and support systems, said: “It’s complicated and big – a giant system.”

The system is designed to simulate different types of seismic activity, and it can be reconfigured to adapt to and represent different types of soils. This versatility, Laplace said, will allow him to support a wide variety of research opportunities.

“The soil should be representative of a particular site, but preparing it with the right consistency is difficult,” he said. “This is where research comes in. As we reach levels of experimental certainty, our testing will help improve design, build efficiency and reduce build time. It is a new field of construction and engineering.

Looking back on the project – from concept to completion of successful demonstrations in late summer 2022 – Elfass describes a process that involved considerable testing, risk mitigation, “artistic effort” and perseverance. Faced with a challenge, Elfass said, “We got things done.”

“We say ‘yes’. Then we look for ways to do that,” Elfass added.

Other team members on this ambitious project were technicians Chad Lyttle and Todd Lyttle who executed the complex construction. College of Engineering Professor Raj Siddharthan and Associate Professor Ramin Motamed provided valuable advice to the project.

Several local companies provided critical components to the project, including Dynamic Isolation Systems, Motion and Flow Control Products, Precision Metals, Remarc Manufacturing, Reno Iron Works, and Western Nevada Supply.

Experiments conducted with the Soil Box System will provide data for another national effort, EQSIM: an ongoing collaboration between scientists at Lawrence Berkeley National Lab, Lawrence Livermore National Laboratory, and the University of Nevada, Reno, to develop Realistic and highly detailed earthquake simulations using DOE. state-of-the-art supercomputers.

Thanks to these exceptionally fast machines, the long-standing goal of computer modeling of a complete regional-scale structure-breaking sequence becomes a reality. Their ground motion simulations will then be made available to the public through the Pacific Earthquake Engineering Research Center’s open-access seismic ground motion database. PEER is a multi-institution research center focused on performance-based earthquake engineering, led by UC Berkeley and of which the University of Nevada, Reno is a member.

“Together, our work will inform DOE’s facility safety interests, but the laminar floor box will also be available to a wide range of seismic safety actors,” said College of Engineering Dean Erick Jones. . “This aligns with the College’s commitment to equitable community infrastructure to mitigate cascading local, regional and global risks.”

Visit the University’s Civil Engineering Earthquake Research Center website for more information.

Photo caption: The design and construction team (lr): Professor Raj Siddharthan, Associate Research Professor Sherif Elfass, Associate Professor Ramin Motamed, Foundation Professor Ian Buckle, Project Leader and Director of the Center for Research in Earthquake Civil Engineering from David McCallen University, Research Associate Professor Patrick Laplace, Technician Todd Lyttle and Technician Chad Lyttle.

Note: Aliyah Kovner, Science Writer and Podcast Producer, Lawrence Berkeley National Laboratory, and Mike Wolterbeek, Communications Manager, University of Nevada, Reno, contributed to this story.

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