Jose I. Restrepo - US grants

Abstract
CMS-0217293
Seible

The George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) is a project funded under the National Science Foundation Major Research Equipment and Facilities Construction account. This cooperative agreement, awarded under NEES, establishes a NEES large high performance (LHP) outdoor shake table site at the University of California, San Diego (UCSD) and is an outcome of the peer review of proposals submitted to program solicitation NSF 01-164, "NEES: Earthquake Engineering Research Equipment, Phase 2." This outdoor shake table will be a 7.6 m x 12.2 m long single (horizontal) degree-of-freedom system. The table will have a peak horizontal velocity of 1.8 m/s, maximum stroke of +/-0.75 m, maximum gravity (vertical) payload of 200 MN, maximum overturning moment of 50 MN-m, force capacity of actuators of 6.8 MN, and a frequency bandwidth from 0-20 Hz. The major equipment for the LHP shake table facility consists of servocontrolled dynamically-rated actuators with large-servo valves, a large power supply, a vertical load/overturning moment bearing system, a digital three-variable real-time controller, concrete foundation and reaction mass, and weatherproofing system. The facility will be the only outdoor shake table in the U.S. and will enable large/full-scale testing of structural systems and soil-foundation-structure interaction that cannot be readily extrapolated from testing at smaller scale, or under quasi-static or pseudo-dynamic test conditions, as well as testing large-scale systems to observe their response under near source ground motion. The LHP outdoor shake table will be located 15 km from campus at the UCSD Camp Elliott field site. This two-acre site was selected so that the shake table could be used in conjunction with an adjacent soil pit and laminar shear soil box being provided by the California Department of Transportation. This site will allow room for multiple test specimens to be constructed and instrumented before placement on the shake table. A 177 kN rough terrain crane will be provided at Camp Elliott for loading, unloading, and everyday construction purposes. For heavier lifting capabilities, an 880 kN crane will be available on an as needed rental basis, with the individual experiment requiring the larger crane to cover this cost. This equipment will be operational by September 30, 2004, and will be managed as a national shared-use NEES equipment site, with teleobservation and teleoperation capabilities, to provide new earthquake engineering research testing capabilities through 2014. Shared-use access and training will be coordinated through the NEES Consortium. UCSD is providing $1,363,000 in cost sharing for this facility. UCSD will integrate this shake table equipment into its research program involving undergraduate and graduate students, Department of Structural Engineering curriculum, and K-12 and general public outreach. The University will also provide training opportunities for outside faculty, students, and practitioners through web-based tutorials and on-site training.

Abstract
The objective of this Major Research Instrumentation (MRI) project is to procure instrumentation and equipment specifically for an Explosive Loading Laboratory (ELL), which is currently under construction. The ELL will allow for one-of-a-kind real time blast and impact testing of structural components, assemblies, and systems of critical infrastructure such as buildings and bridges in a controlled environment. The testing laboratory is the first facility in the world that can accurately and repeatedly performs simulated explosive loading tests and characterize their effects on structures for use in developing retrofit and hardening optimization technologies without creating actual explosions.
During large- or full-scale testing of structural systems or assemblies at the ELL, a large array of sensors will be distributed in specific locations such that precise measurements can be obtained to investigate the development of non-linear failure mechanisms. A vital element in the development of the ELL is the procurement of robust, state-of- the-art instrumentation and sensors that can be operated in an outdoor environment, data acquisition systems and high performance networking capabilities. The key components are: real-time distributed data-acquisition systems, a high-speed digital camera, camera measurement systems, a range of conventional sensors such as DCDTs.
The vision is to provide the ELL with sufficient instrumentation that can be used to integrate state-of-the-art blast engineering experimental and computational research into educational curriculum using internet-based technologies. The equipment requested for the ELL can be leveraged to promote research being conducted at the Scripps Institute of Oceanography (SIO) at UCSD, for further development of ROADNet, a network and information management system that will deliver data to a variety of end users in real-time.
The state-of-the-art ELL facility, will add a significant new dimension and capabilities to existing United States testing facilities and promote research in Structural Engineering, Dynamic Systems and Control, and Information Technology.

This award provides funding for University of California - San Diego (UCSD) to purchase advanced instrumentation and do associated work for the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) - Large High Performance Outdoor Shake Table (LHPOST), that will be operated by NEES Consortium, Inc., as a national shared use facility during FY 2005 - FY 2014. This funding is provided for the procurement of a distributed data acquisition system and a range of sensors (displacement transducers, accelerometers and an optical displacement measurement system) that can be deployed outdoors and used in large-scale experimentation. Such equipment is necessary for the operation of NEES Large High Performance Outdoor Shake Table (LHPOST).
The instrumentation includes: A distributed data acquisition system which will initially consist of a central control computer, a central distribution terminal, and eight 64-channel general purpose distributed data acquisition system. Under this funding a total of 256 channels will be acquired; Sensotec transducer is a 50 mm stroke transducer that will provide infinite resolution and a maximum nonlinearity of 0.25% of full scale which will be used to obtain quantities such as displacements, rotations, curvatures or shear deformations. Twenty-four transducers will be funded under this proposal; The Ametek Rayelco Model PSS-50A-HT transducer is a submersible wire potentiometer with a total stroke of 50 inches. It will be used for measuring larger displacements. Thirty-six transducers of this type will be purchased with funds recommended in this proposal; The Crossbow LP series accelerometers are general- purpose linear acceleration sensors available in various ranges. Sixteen 4 g tri-axial Crossbow LP series accelerometers will be purchased with funds recommended in this proposal; ShapeMonitor is a turnkey system that allows for measuring objects in real-time. The system comprises a high-speed computer, frame grabber, dual digital cameras for data acquisition and a target projector. ShapeMonitor
allows for measurement of objects whether they are static or dynamic. The system can also be used in harsh environments and poor platform stability where laser systems fail. The ShapeMonitor program is hardware independent. This camera system will be used for monitoring the response and image-post processing of the sub-assemblage and systems level specimens. This augmented instrumentation will enable researchers to obtain quality data gained from the landmark tests conducted by NEES users on the LHPOST using the requested equipment and sensors. This award is funded by the NSF NEES Major Research Equipment and Facilities Construction (MREFC) project and is a component of the National Earthquake Hazards Reduction Program (NEHRP).

ABSTRACT

Unreinforced masonry in fills are frequently found as interior partitions and exterior walls in buildings, and are normally treated as non-structural elements. However, unlike most non-structural components, they can develop a strong interaction with the bounding frames when subject to earthquake loads and, therefore, contribute significantly to the lateral stiffness and load resistance of the structure. In spite of the research that have spanned several decades, the performance of these structures in a severe earthquake remains a major controversy among structural engineers and researchers today. The main aim of the proposed research is to develop rational and reliable methodologies for assessing the seismic safety and performance of masonry unfilled RC frames, and develop practical and effective techniques for the seismic retrofit of these structures using conventional as well as innovative materials. The project will include the development of reliable analysis tools that range from advanced computational models to simple analytical methods that can be used in engineering practice. The project will take advantage of the vast computational resources and experimental facilities provided by NEES. The analysis methods and retrofit techniques will be first validated with medium-scale experiments to be
conducted with the NEES Fast Hybrid Test facility at the University of Colorado at Boulder. Final proof-of-concept tests will be conducted on a 3/4-scale three-story RC frame using the NEES Large High Performance Outdoor Shake Table at the University of California at San Diego. Stanford University will focus on the development of sprayable high-performance fiber-reinforced cement-based composites for infill retrofit. The work will be carried out as a multi-institutional, inter-disciplinary effort by a diverse research team with expertise in professional practice, structural design, structural testing, structural analysis, computational mechanics, and composite materials.

Understanding and assessing the seismic performance of masonry-infilled non-ductile RC frames presents a most difficult problem in structural engineering. Currently, there are no reliable engineering guidelines for this. Analytical tools to evaluate the complicated frame-infill interaction and the resulting failure mechanisms need to be built on the fundamental principles of mechanics and sound engineering judgment. It is far more challenging than analyzing a pure RC or masonry structure. This research will fill a major gap in the modeling and performance assessment of this class of existing structures that can be frequently found in regions of high seismic risk and the development of effective retrofit strategies to prohibit the undesired failure mechanisms from a system perspective. The project will involve the development of new design and assessment techniques, new materials, and cutting-edge computational methods, which will be intellectually stimulating.

The leverage provided by the successful programs on education and outreach that are already in place at UCSD, CU, and Stanford, and the additional resources that will be secured outside NEES will reinforce the common education and outreach goals of NEESinc. The proposed round-robin studies and outreach activities using the collaboratory tools, and the telepresence and data archiving and mining capabilities provided by the NEESgrid will assure timely dissemination of information to the broad engineering and lay communities. The advanced computational models developed in this project will be readily applicable to many new and existing structures and provide a 3-D model-based simulation capability that can potentially replace physical experiments in a foreseeable future. The implementation of the advanced computational models in a public-domain software, OpenSEES, which is supported by the NEESgrid, will benefit the earthquake engineering community at large. The retrofit techniques explored can potentially lead to significant savings by building owners and enhance the seismic safety of a large number of existing structures. The simplified analytical tools, design and assessment methodologies, and
experimental data will provide the much needed information and tools for the next-generation
performance-based seismic design guidelines on this class of structures. The integration of design, computation, and experimentation in this project provide a unique experience for the training of future earthquake engineers on performance-based engineering.

Abstract:


The objective of this proposal is to build an approximately half-scale model of a section of a precast concrete parking structure on the large-scale shake table at the NEES site at the University of California-San Diego. This is an important addition to other tests and analytical studies being conducted cooperatively at the University of Arizona, UCSD and Lehigh University. Field surveys after several U.S. earthquakes have shown that this structural system often provides poor resistance to seismic loads. The research is a closely integrated analytical and experimental effort intended to significantly advance fundamental knowledge of the seismic behavior of precast floor diaphragms during earthquakes. This is a very complex system under dynamic loads and is a very popular structural system for certain types of structures. This analytical and experimental effort intended to significantly advance knowledge of the seismic behavior of precast floor diaphragms with the specific objective of producing an appropriate seismic design methodology for eventual code implementation. This objective is realized through regular input from an active industry task group with a strong presence on code-writing bodies.

This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes the University of California, San Diego (lead institution), San Diego State University (subaward), and Howard University (subaward). This project will utilize the NEES equipment sites at the University of California, San Diego (UCSD) and the University of California, Los Angeles (UCLA). Additional core project team members include industry members leading code development activities and researchers at Worcester Polytechnic Institute.

Intellectual Merit: Nonstructural components and systems (NCS) are those elements within a building that do not contribute to the building's load bearing system. NCSs are generally categorized as being either an architectural, mechanical, plumbing, or content item or system of items. Since the 19th century, NCSs have demonstrated their potential to create a dangerous environment for building occupants during earthquake shaking. Since these elements generally represent more than 80% of the total investment of a building, even minor damage can translate to significant financial losses. In fact, over the past three decades, the majority of earthquake-induced direct losses in buildings are directly attributed to NCS damage. Of the handful of full-scale building experiments conducted in the United States, none have specifically focused on evaluating the response of nonstructural component and systems (NCSs) during earthquake shaking. This project involves a landmark test of a full-scale, five-story building completely furnished with NCSs, including a functioning passenger elevator, partition walls, cladding and glazing systems, piping, HVAC, ceiling, sprinklers, and other building contents, as well as passive and active fire systems. The NEES-UCSD and NEES-UCLA equipment combine to realize this unique opportunity and hence advance understanding of the full-scale dynamic response and kinematic interaction of complex structural and nonstructural components and systems. While most NCSs in these experiments will be designed to the latest state of the art building code seismic provisions, non-seismic detailed designs widely used in low-seismic regions of the United States will also be included. Furthermore, this research will investigate the potential for protecting critical NCS systems using, for example, damping and/or isolation methods. Data from these unique experiments will be used to compare earthquake performance predictions determined using available commercial and research computational modeling platforms. Research at the system level that incorporates the structure and the NCSs and addresses issues such as detrimental kinematic and dynamic interaction between systems components is lacking. This research will enable, for the first time, tests of complex systems, which look closely at multidisciplinary issues, using facilities that are fully equipped to investigate, in a controlled environment, the effects of earthquakes on building-NCS system performance.

Broader Impacts: Outcomes from this research will have broad and immediate impacts on the performance-based design of NCSs, including NCS fire protection systems. This research will support doctoral students in the earthquake engineering area and master students in construction management and protective systems areas. The project has developed unique partnerships to attract a diverse student group to earthquake engineering via educational activities that engage faculty and students from Howard University, as well as high school students from the Construction Tech Academy (an engineering and construction magnet program in San Diego). Data from this research will be archived and made available to the public through the NEES data repository.

The objective of this Rapid Research Response (RAPID) award is to gather perishable data on the damage to two precast concrete buildings during the February 2011 magnitude 6.3 Christchurch, New Zealand, earthquake. This project is a collaboration among researchers from the University of California-San Diego, University of Arizona, and University of Canterbury. Project team members will travel to Christchurch and catalog earthquake damage (foundation, structural and non-structural) through visual observation. The post-earthquake structural state will be determined by means of collecting ambient vibration and potential aftershock dynamic response. An array of accelerometers loaned from the NEES facility at the University of California, Los Angeles will be temporarily deployed to monitor and record these vibrations. Sensors will be strategically distributed to capture the predominant modes of vibration and concentrated at the foundation to capture soil-structure interaction. This data will be post-processed for a first-level system identification and characterization of the damaged buildings.

Cataloging post-earthquake damage is an established practice for the benefit of seismic design. Forensic engineering is an essential catalyst of modern building codes. The technique advances the field of earthquake engineering leading to better designs, seismic details, and construction methods. These two buildings are important to the earthquake engineering research community and the precast concrete industry in the United States because of relevant construction and designs. With state-of-the-art seismic design guidelines in place, the two buildings performed as intended, well beyond the life-safety minimum of seismic design philosophy in New Zealand and the United States. Structural damage was sustained as expected, with the buildings' structural integrity remaining intact. To replicate this desirable performance in future buildings, the damage needs documenting to advance the earthquake engineering practice before repairs eliminate the opportunity. Participation by researchers at three universities in two countries will strengthen the infrastructure for research on an international level. Educational outreach is leveraged by introducing an undergraduate student to international collaborative research, forensic engineering, sensors, data acquisition, and seismic resilience with an NSF-supported Research Experiences for Undergraduates site through the Pacific Earthquake Engineering Research Center at the University of California, Berkeley.

The large, high-performance, outdoor shake table (LHPOST) experimental facility at the University of California, San Diego, is the largest facility of its kind in the United States for conducting earthquake engineering research on civil infrastructure, and has the world's largest payload capacity (20 MN). Because there are no overhead height restrictions, this facility can accommodate the tallest structures ever tested on any shake table. The LHPOST, originally designed to accommodate six degrees of freedom (6DOF), was supported for construction during 2002-2004 as a single degree of freedom (SDOF) system, by the National Science Foundation (NSF), Network for Earthquake Engineering Simulation (NEES), Major Research Equipment and Facilities Construction account, due to budgetary constraints. As an SDOF system and a multi-user national research facility, the LHPOST has been supported by NSF for operations and maintenance under the NEES (FY 2005-FY 2014) and the Natural Hazards Engineering Research Infrastructure (NHERI) (FY 2015 to date) programs. This award will upgrade the LHPOST from its current SDOF configuration to a full 6DOF capability. In its upgraded configuration, the LHPOST will be able to reproduce all six components of motion (two horizontal and vertical translational components, as well as pitch, roll, and yaw rotational components) experienced by the ground during earthquakes. It will provide a one-of-a-kind facility to test large to full size civil infrastructure, such as structural, nonstructural, geo-structural and soil-foundation-structural systems, under strong earthquake excitation. The ability to test infrastructure under the full range of combined horizontal, vertical, and rotational seismic input motion is critical for research that can lead to effective, economical,and practical new infrastructure designs, as well as seismic rehabilitation and retrofit strategies for existing infrastructure, to improve the seismic performance for post-earthquake resilience, public safety, and national welfare. The 6DOF LHPOST will provide critical landmark datasets to support the development, calibration, and validation of high-fidelity, physics-based computational models of civil infrastructure systems that will progressively shift the current reliance on physical testing to model-based simulation for the seismic design and performance assessment of such systems. The experimental capabilities provided by the 6DOF LHPOST will support U.S. leadership in earthquake engineering research. The upgraded shake table will also provide a unique tool to educate graduate, undergraduate, and K-12 students, as well as the news media, policy makers, infrastructure owners, insurance providers, and the public, about natural disasters and the national need to develop effective technologies and policies to prevent earthquakes from becoming societal disasters. This award supports the National Earthquake Hazards Reduction Program (NEHRP).

The upgrade of the LHPOST to 6DOF will be achieved by adding two horizontal actuators and reconfiguring all four horizontal actuators into a V-shape at both longitudinal ends of the shake table's 12.2 meter long by 7.6 meter wide platen to provide bi-axial horizontal motions, as well as the yaw motion capabilities. Each of the existing six pressure balanced vertical actuators/bearings will be equipped with a high-flow servovalve to enable vertical, pitch, and roll motion capabilities. To operate the 6DOF table, the number of hydraulic power units will be increased from two to four and the total size of the accumulator banks will be increased from 9,500 to 37,800 liters. A new piping system will be installed between the accumulator banks, the horizontal and vertical actuators, and the surge tank. A third nitrogen-filled hold-down strut will be installed between the bottom of the platen and the bottom of the reaction block to increase the overturning moment capacity of the table. The existing SDOF shake table controller (both hardware and software) will be replaced by a controller with 6DOF capabilities. A new hydraulic distribution system controller will also be provided to handle the safety interlocks, control of the hydraulic power units, and control of the accumulator charging and blowdown. Additionally, the height of the existing four safety towers will be doubled to protect the hydraulic power building from potential specimen collapse. During the upgrade, operations of the shake table under NHERI will cease for a period of 14 months between mid-2020 and mid-2021. Before reopening the facility for operations and research, commissioning of the facility, including acceptance and characterization tests, will be performed.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

This Major Research Instrumentation (MRI) award supports the acquisition of a versatile, high-performance data acquisition system (DAQ) for fundamental research at the NSF Large High-Performance Outdoor Shake Table (LHPOST) at UC San Diego. To advance fundamental knowledge, it is vital to collect and disseminate highly accurate earthquake engineering experimental datasets that are well documented. Such data on system-level behavior of civil infrastructure during earthquakes--from the initiation of damage to the onset of collapse--are scarce. The MRI- enabled LHPOST facility will allow researchers to conduct in-depth seismic response studies of complex large-scale civil infrastructure systems?pushing the boundaries of knowledge on resilient communities and contributing to enhanced design codes and standards to promote public safety. Research activities will broadly impact science, technology and engineering practice and the data collected from the new DAQ system will be integrated into course work that will bring the laboratory experience into the classroom, reaching a large number of students, particularly underrepresented students.

The LHPOST is currently being upgraded from its current single-degree-of-freedom (SDOF) configuration to a full six-degree-of-freedom (6-DOF) capability-- to reproduce all six components of ground motion experienced during earthquakes. The DAQ system will complement this upgrade--providing higher resolution (24-bit, 768 channels, max sampling rate of 25.6 kS/sec per channel), superior aliasing rejection with user-configurable digital anti-aliasing filters, and zero skew time between different channels, thus enabling accurate recordings from very small (ambient vibrations) to very large (seismic testing) motions. This will facilitate the generation of critical landmark datasets to support the development, calibration, and validation of high-fidelity 3D computational models of civil infrastructure systems that will progressively shift the current reliance on physical testing to simulation-based assessment and design. The instrumentation will help to enable potentially transformative research on soil-structure interaction, hybrid testing and measurement of structural response during dynamic loading. The high-quality data enabled by this instrumentation will be made available through the Natural Hazards Engineering Research Infrastructure (NHERI) repository?serving a global community of researchers and catalyzing collaborative research.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

The Natural Hazards Engineering Research Infrastructure (NHERI) is supported by the National Science Foundation (NSF) as a distributed, multi-user national facility to provide the natural hazards engineering research community with access to research infrastructure that includes earthquake and wind engineering experimental facilities, cyberinfrastructure (CI), computational modeling and simulation tools, high performance computing resources, and research data, as well as education and community outreach activities. Originally funded under program solicitations NSF 14-605 and NSF 15-598, NHERI has operated since 2015 through separate, but coordinated, five-year research infrastructure awards for a Network Coordination Office, CI, Computational Modeling and Simulation Center, and Experimental Facilities, including a post-disaster, rapid response research facility. Information about NHERI resources is available at the NHERI web portal (https://www.DesignSafe-ci.org). Awards made for NHERI contribute to NSF's role in the National Earthquake Hazards Reduction Program (NEHRP) and the National Windstorm Impact Reduction Program (NWIRP). NHERI Experimental Facilities will provide access to their experimental resources, user services, and data management infrastructure for NSF-supported research and education awards. This award will renew the operations of the large high-performance outdoor shake table (LHPOST) Experimental Facility located at the University of California, San Diego, to support research in structural and geotechnical earthquake engineering. The LHPOST was recently upgraded through NSF award 1840870 to six degrees-of-freedom (6-DOF) capabilities (LHPOST6) and can reproduce the surface ground motions resulting from major earthquakes, including the three translations and three rotations of the ground surface. The shake table can support test structures with no height limitations and weighing up to 4.4 million pounds (20 meganewton). Building seismic-resilient and sustainable communities requires understanding and reliably predicting the seismic system-level response of buildings, critical facilities, utilities, lifelines, and other civil infrastructure systems. The experimental research conducted on the LHPOST6, together with computational models making use of the datasets collected from shake table tests, will advance the science, technology, and practice in earthquake engineering, leading to next-generation design codes and decision-making tools that will increase the seismic resilience and sustainability of the built environment. Experiments performed at this facility will have a significant educational impact by providing life-size demonstrations of the seismic performance of structural, geotechnical, and soil-foundation-structural systems to graduate, undergraduate, and K-12 students from diverse backgrounds, and will also educate the public about the urgency of the nation’s efforts to develop effective technologies and policies to prevent natural hazards from becoming societal disasters. The research activities will train next-generation researchers, educators, and practitioners, who will be future leaders in natural hazard mitigation. An active outreach program will include annual user training and industry-academia workshops, Research Experiences for Undergraduates, traditional and social media campaigns, webinars from users of the facility, and computational challenges competitions.<br/><br/>The LHPOST6 facility will transform natural hazard mitigation research by enabling large/full-scale system tests that will: (a) provide fundamental knowledge for understanding complete system behavior during earthquakes, from initiation of damage to the onset of collapse, including the effects of soil-foundation-structure interaction, the contributions of lateral and gravity load-resisting systems, and non-structural systems; (b) provide data for the development, calibration, and validation of high-fidelity physics-based computational models, therefore reducing future reliance on physical testing; (c) provide data and fragility information, which with validated simulation tools, will enable the full realization of performance-based design, the most rational/scientific way to evaluate and reduce the risks of natural hazards on the community; (d) provide validation tests for innovative structural systems and retrofit methods, as well as new materials, components, and manufacturing/construction methods for seismic protection; and (e) permit full-scale modeling of near-surface geotechnical systems and exploration of geotechnical phenomena and soil improvement techniques that cannot be explored at laboratory scale. The LHPOST6 will enable researchers to investigate the combined effect of realistic near-field translational and rotational earthquake ground motions on densely instrumented large/full-scale structural, geotechnical, or soil-foundation-structural systems, including the effects of kinematic and inertial soil-foundation-structural interaction, nonlinear soil and structural response, liquefaction, and seismic compression. Experimental data produced by the testing at this facility will be archived and made publicly available in the NHERI Data Depot (https://www.DesignSafe-ci.org).<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.