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

Numerical analyses were performed to study the cluster suction bucket foundation performance in comparison with the monopod suction bucket foundation. The possibility of improving the resistance performance of suction bucket foundations by using cluster configuration was studied. Clustered foundations are formed by arranging multiple bucket foundations in relatively short distances among them. A model cluster foundation composed of three individual buckets was configured such that it has the same cross sectional area, length and total bucket weight to a monopod foundation. Results of numerical modeling are presented in the form of load-displacement curves. Vertical, horizontal and horizontal combined with moment load conditions were considered. The results show that the cluster type configuration improved the resistance performance of the foundations under typical loading conditions.Copyright © 2013 by ASME

Numerical Analysis of Cluster and Monopod Suction Bucket Foundation

Piles installed to increase bearing capacities of super structures in soft soil layers are vulnerable to horizontal loads such as seismic loads. This study aims to verify the stability of piles used for a pile supported slab track system using dynamic centrifuge test and numerical analysis. First of all, validation of the numerical analysis method was performed by comparing the seismic response from the two methods: dynamic centrifuge test and its numerical model. Verifications were also obtained for four different centrifuge test model setups. Numerical models were designed similar to the physical models on a prototype scale. The numerical method solves the dynamic problem by an explicit method in the time-integration stage. The acceleration response of the slab track and bending moment of the pile show good agreement between the two methods. Based on the verified numerical analysis model, the parametric studies for embankment thickness and soft ground stiffness were performed, in addition, the seismic stability of pile supported slab track was evaluated.

Centrifuge and Numerical Simulation of Pile Supported Slab Track System Behavior on Soft Soil under Seismic Loading

https://www.jstage.jst.go.jp/article/jgssp/4/7/4_v04.k10/_pdf

Review of offshore monopile design for wind turbine towers

Korea has started to build wind farms in the Yellow Sea, with the seabed consisting of a thick silty sand deposit. It is therefore important to understand the behavior of potential foundati...

Behavior of a Monopod Bucket Foundation Subjected to Combined Moment and Horizontal Loads in Silty Sand

A suction anchor is one of the most popular anchors for deepsea floating systems. An anchor used for catenary mooring is predominantly under a horizontal load. In this study, the behavior of a suction anchor installed in cohesionless soil was investigated when the anchor was mainly subjected to a horizontal load induced by a catenary line. In order to study the behavior of the suction anchor, 3D FEM analysis models were developed and analyzed. Depending on the location of the load (padeye), the ultimate horizontal load was monitored. The distributions of the reaction forces around the anchor induced by the seabed were analyzed using the circumferential stress to understand the behavior of the suction anchor under a horizontal load.

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Yun Wook Choo

Papers

Numerical Analysis of Cluster and Monopod Suction Bucket Foundation

Centrifuge and Numerical Simulation of Pile Supported Slab Track System Behavior on Soft Soil under Seismic Loading

Review of offshore monopile design for wind turbine towers

Behavior of a Monopod Bucket Foundation Subjected to Combined Moment and Horizontal Loads in Silty Sand

Capacity of Horizontally Loaded Suction Anchor Installed in Silty Sand