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This paper focuses on the abilities of the Large High-Performance Outdoor Shake Table (LHPOST6) at UC San Diego to investigate the combined effects of realistic near-field translational and rotational earthquake ground motions applied as dynamic excitation to 3-D and large- or full-scale structural, geotechnical, or soil-foundation-structural systems. The LHPOST6 supports the advancement of innovative materials, manufacturing methods, detailing, earthquake protective systems, seismic retrofit methods, and construction methods, and is a driving force towards improving seismic design codes and standards and developing transformative seismic-resistant concepts. This paper provides: (i) a brief overview of the 6-DOF capabilities of the LHPOST6 facility; (ii) an overview of the research projects conducted so far at the LHPOST6 facility focusing on the performance of the facility, and (iii) new seismic research opportunities enabled by the LHPOST6 to provide data and fragility information on structural and geotechnical systems that can support the full realization of performance- and resilient-based seismic design. 

The thermo-mechanical behavior of saturated clays during a heating/cooling cycle is relevant from the perspective of understanding different types of energy geostructures as well as understanding the use of heat for soil improvement. This paper involves a study of the effect of a heating/cooling cycle on the preconsolidation stress of saturated normally consolidated clays. Although many studies have observed a decrease in preconsolidation stress (thermal softening) after heating of overconsolidated soils, fewer studies have investigated changes in preconsolidation stress of normally consolidated soils. Available thermo-elasto-plastic models indicate that a heating-cooling cycle will lead to thermal contraction and an apparent overconsolidation effect for normally consolidated soils (thermal hardening), but inconsistencies in the literature have been observed. This study involves the use of a thermal triaxial cell to first consolidate kaolinite clay to normally consolidated conditions, apply a drained heating or a heating/cooling cycle, followed by mechanical loading to higher mean effective stresses. The tests presented in this study confirm that cooling also induces an apparent overconsolidation effect on the initially normally consolidated clay, but with a preconsolidation stress greater than that expected from the initial virgin consolidation line before heating. The results are a positive finding regarding the possible use of heat to improve the mechanical response of soft clays. 

This paper focuses on the results from thermal triaxial tests on normally consolidated Georgia Kaolinite. The hypothesis evaluated in this study is whether the initial mean effective stress has an impact on the thermal volume change encountered during drained heating. To that effect, specimens at three different initial mean effective stresses were considered in this study. The clay specimens were first isotropically consolidated to a normally consolidated state, then subjected to a drained heating cooling cycle followed by further mechanical loading to higher effective stresses. The results indicate contractive volumetric strain during drained heating where the volumetric strain was found to increase with increasing initial mean effective stress. A rebound in volume was observed during subsequent cooling where the net change in volume transitioned from zero volume change of the specimen to net contraction of the specimen after a heating cooling cycle as the initial mean effective stress increased. The results indicate the need for considering the effect of initial mean effective stress when assessing in-situ heating as a method of soil improvement.