NHERI@UC San Diego 6-DOF Large High-Performance Outdoor Shake Table Facility

Lelli Van Den Einde,Chin-Ta Lai,Marty Halvorson,Brad Thoen,José I Restrepo,Ricardo Bustamante,Koorosh Lotfizadeh,Sebastian Restrepo,J Enrique Luco,P Benson Shing,Ozgur Ozcelik,Mike Nemeth,Machel L Morrison,Georgios Tsampras,Gilberto Mosqueda,Tara C Hutchinson,Andrés Rodriguez,Joel P Conte

doi:10.3389/fbuil.2020.580333

Abstract

Since its commissioning in 2004, the UC San Diego Large High-Performance Outdoor Shake Table (LHPOST) has enabled the seismic testing of large structural, geostructural and soil-foundation-structural systems, with its ability to accurately reproduce far- and near-field ground motions. Thirty-four (34) landmark projects were conducted on the LHPOST as a national shared-use equipment facility part of the National Science Foundation (NSF) Network for Earthquake Engineering Simulation (NEES) and currently Natural Hazards Engineering Research Infrastructure (NHERI) programs, and an ISO/IEC Standard 17025:2005 accredited facility. The tallest structures ever tested on a shake table were conducted on the LHPOST, free from height restrictions. Experiments using the LHPOST generate essential knowledge that has greatly advanced seismic design practice and response predictive capabilities for structural, geostructural, and non-structural systems, leading to improved earthquake safety in the community overall. Indeed, the ability to test full-size structures has made it possible to physically validate the seismic performance of various systems that previously could only be studied at reduced scale or with computer models. However, the LHPOST's limitation of 1-DOF (uni-directional) input motion prevented the investigation of important aspects of the seismic response of 3-D structural systems. The LHPOST was originally conceived as a six degrees-of-freedom (6-DOF) shake table but built as a single degree-of-freedom (1-DOF) system due to budget limitations. The LHPOST is currently being upgraded to 6-DOF capabilities. The 6-DOF upgraded LHPOST (LHPOST6) will create a unique, large-scale, high-performance, experimental research facility that will enable research for the advancement of the science, technology, and practice in earthquake engineering. Testing of infrastructure at large scale under realistic multi-DOF seismic excitation is essential to fully understand the seismic response behavior of civil infrastructure systems. The upgraded 6-DOF capabilities will enable the development, calibration, and validation of predictive high-fidelity mathematical/computational models, and verifying effective methods for earthquake disaster mitigation and prevention. Research conducted using the LHPOST6 will improve design codes and construction standards and develop accurate decision-making tools necessary to build and maintain sustainable and disaster-resilient communities. Moreover, it will support the advancement of new and innovative materials, manufacturing methods, detailing, earthquake protective systems, seismic retrofit methods, and construction methods. This paper will provide a brief overview of the 1-DOF LHPOST and the impact of some past landmark projects. It will also describe the upgrade to 6-DOF and the new seismic research and testing that the LHPOST6 facility will enable.

Highlights

The upgrade of the University of California at San Diego Large High Performance Outdoor Shake Table (LHPOST) funded by the National Science Foundation (NSF) Natural Hazard Engineering Research Infrastructure (NHERI) network from one to six degrees of freedom (6-Degree of Freedom Control (DOF)) is critical for the economical design, construction, and implementation of improved seismic mitigation strategies
The tallest structures ever tested on a shake table have used the LHPOST, which has no roof overhead, and is free from height or crane capacity restrictions
The LHPOST6 facility will be equipped with a new data acquisition (DAQ) system consisting of 12 nodes with 64 channels each at 24bit Analog-to-Digital resolution, simultaneous sampling, and a sampling rate up to 25.6 kS/s per channel

Summary

INTRODUCTION

The upgrade of the University of California at San Diego Large High Performance Outdoor Shake Table (LHPOST) funded by the National Science Foundation (NSF) Natural Hazard Engineering Research Infrastructure (NHERI) network from one to six degrees of freedom (6-DOF) is critical for the economical design, construction, and implementation of improved seismic mitigation strategies. The landmark NSF-funded Building Non-structural Components and Systems (BNCS) test program (refer to #14, Pantoli et al, 2016a) incorporated a complete suite of NCSs, including operable egress (stairs and elevators), facades (precast concrete and light-weight cold-formed steel), and interior equipment and architectural support contents (ceilings, HVAC, piping, etc.). This project focused on the “total building” and, in particular, the interactions between components (non-structuralto-non-structural and structural-to-non-structural) and offered new insight into understanding the seismic response of a wide range of NCSs, but the tests were carried out under single-axis ground motions. The LHPOST6 can support the testing of underground pipelines subject to liquefaction loads or fault crossing demands by taking advantage of the large displacement capacity of the LHPOST6, enabling researchers to conduct large-scale dynamic testing of underground facilities and pipelines and techniques for evaluating ground movement patterns and stability for a variety of excavation, tunneling, micro-tunneling, and mining conditions (O’Rourke et al, 2008)

SUMMARY AND CONCLUSIONS

Findings

DATA AVAILABILITY STATEMENT