Damage constitutive model based on energy dissipation for intact rock subjected to cyclic loading

Community resilience has been addressed across multiple disciplines including environmental sciences, engineering, sociology, psychology, and economics. Interest in community resilience gained momentum following several key natural and human-caused hazards in the United States and worldwide. To date, a comprehensive community resilience model that encompasses the performance of all the physical and socio-economic components from immediate impact through the recovery phase of a natural disaster has not been available. This paper summarizes a literature review of previous community resilience studies with a focus on natural hazards, which includes primarily models of individual infrastructure systems, their interdependencies, and community economic and social systems. A series of national and international initiatives aimed at community resilience are also summarized in this study. This paper suggests extensions of existing modeling methodologies aimed at developing an improved, integrated understanding of resilience that can be used by policy-makers in preparation for future events.

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State of the research in community resilience: progress and challenges.

The first large scale geotechnical centrifuge in Korea has recently been developed at KAIST under the Korea Construction Engineering Development (KOCED) Collaboratory program. A 5 m platform radius, 240 g-tons state-of-the-art geotechnical centrifuge has been installed in a new facility. The centrifuge has the unique feature of an automatic balancing system and includes parts for general testing purposes such as fluid rotary joints, slip rings, a fiber optic rotary joint and an Ethernet network system. In addition, a four degree-of-freedom in-flight robot can be equipped to simulate complex construction or in-situ testing process during centrifuge flight. In order to simulate earthquake motion during operation, a self-balancing type biaxial shaking table has also been developed. Since the KOCED program promotes collaboration and remote use, tele-presence and tele-participation environments have been implemented in this facility.

A Newly Developed State-of-the-Art Geotechnical Centrifuge in Korea

Analysis of buried pipelines subjected to reverse fault motion

The concept of disaster resilience has received considerable attention in recent years and is increasingly used as an approach for understanding the dynamic response to natural disasters. In this paper, a new performance index measuring the functionality of a gas distribution network has been proposed, which includes the restoration phase to evaluate the resilience index of the entire network. The index can also be used for any type of natural or artificial hazard, which might lead to the disruption of the system. The gas distribution network of the municipalities of Introdacqua and Sulmona, two small towns in the center of Italy that were affected by the 2009 earthquake, has been used as a case study. The pipeline network covers an area of 136 km2, with three metering pressure reduction (M/R) stations and 16 regulation groups. Different analyses simulating different breakage scenario events due to an earthquake have been considered. The numerical results showed that the functionality of the medium-pressure gas distribution network is crucial for ensuring an acceptable delivery service during the post earthquake response. Furthermore,the best retrofit strategy to improve the resilience index of the entire network should include emergency shutoff valves along the steel pipes.

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Resilience-Based Design of Natural Gas Distribution Networks

Performance of an equivalent shear beam (ESB) model container for dynamic geotechnical centrifuge tests

Effect of underground tunnel on the ground surface acceleration

Remediation for buried pipeline systems under permanent ground deformation

This paper performed centrifuge load tests of a tripod bucket foundation preliminarily designed as a supporting system of wind turbines and compared the results to those obtained from a test of a monopod bucket foundation. The tripod foundation prototype studied in this study has three bucket caissons, each of which is 6.5 m in diameter and 8.0 m in length. The center-to-center distance between the buckets was 26.9 m. The site is composed of an 11-m thick layer of dense silty sand overlying a thick sandy silt layer. The horizontal load was applied at a height of 33 m from the seabed floor according to the design load condition, and the vertical load was simulated by the self-weight of the model. The moment-rotation angle curves for the tripod foundations were compared with that of the monopod bucket foundation. The moment-rotation curve of the tripod was nearly bilinear, whereas that of the monopod showed a gradual decrease in slope. The yield moment for the tripod foundation was half that of the monopod, but the rotation angle for the yield moment was only 20% that of the monopod. The behavior of the tripod foundation under a cyclic load with respect to the accumulated plastic deformation has also been examined in this study. When the resultant moment of cyclic loading was smaller than the monotonic yield moment, negligible accumulated plastic deformation was observed for both one-way and two-way loading. However, when the resultant moment was higher than the monotonic yield moment, significant cumulated deformation resulted.

Yun Wook Choo

Papers

A Newly Developed State-of-the-Art Geotechnical Centrifuge in Korea

Performance of an equivalent shear beam (ESB) model container for dynamic geotechnical centrifuge tests

Effect of underground tunnel on the ground surface acceleration

Remediation for buried pipeline systems under permanent ground deformation

Investigation of Monotonic and Cyclic Behavior of Tripod Suction Bucket Foundations for Offshore Wind Towers Using Centrifuge Modeling