• Smart Structures and Systems
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• v.14 no.4
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• pp.501-516
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• 2014

The rocking pier system (RPS) allows the columns to rock on beam or foundation surfaces during the attacks of a strong earthquake. Literatures have proved that seismic energy dissipated by the RPS through the column impact is limited. To enhance the energy dissipation capacity of a RPS bridge substructure, frictional hinge dampers (FHDs) were installed and evaluated by shaking table tests. The supplemental FHDs consist of two brass plates sandwiched by three steel plates. The strategy of self-centering design is to isolate the seismic energy by RPS at the columns and then dissipate the energy by FHDs at the bridge deck. Component tests of FHD were first conducted to verify the friction coefficient and dynamic characteristic of the FHDs. In total, 32 shaking table tests were conducted to investigate parameters such as wave forms of the earthquake (El Centro 1940 and Kobe 1995) and normal forces applied on the friction dampers. An analytical model was also proposed to compare with the tested damping of the bridge sub-structure with or without FHDs.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.189-196
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• 2002

The capacity of CFS piers has not been used to a practical design, because there is no guide of a seismic design for CFS piers. Therefore, the guide of a seismic design value is derived from tests of CFS piers in order to apply it to a practical seismic design. Steel piers and concrete-filled steel piers are tested with constant axial load using quasi-static cyclic lateral load to check ductile capacity and using the real Kobe ground motion of pseudo-dynamic test to verify seismic performance. The results prove that CFS piers have more satisfactory ductility and strength than steel piers and relatively large hysteretic damping in dynamic behaviors. The seismic performance of steel and CFS piers is quantified on the basis of the test results. These results are evaluated through comparison of both the response modification factor method by elastic response spectrum and the performance-based design method by capacity spectrum and demand spectrum using effective viscous damping. The response modification factor of CFS piers is presented to apply in seismic design on a basis of this evaluation for a seismic performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.371-378
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• 2002

The design concepts using vibration reduction techniques, or structural control, have been proposed recently to protect infrastructure against earthquakes. The magnetorheological(MR) fluid damper is one of the most promising new devices for structural vibration reduction because of its mechanical simplicity, high dynamic range, low power requirement, large force capacity and robustness. In this study, the seismic performance of MR devices are compared with that of NZ systems as an attempt to provide some data for improving seismic design techniques applied to structures. For nonlinear time domain analysis of a base isolation system, a six-story building model is considered as a numerical example. The ground acceleration data of El Centre 1940, Mexico City 1985 and Kobe 1995 earthquakes are used as seismic excitations. The results show that MR damper systems for outperform NZ systems in wide-ranging seismic excitations with respect to intensity and period characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.464-469
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• 2000

Since the occurrence of 1995 Kobe earthquake, there have been much concern about seismic design for various infrastructures, inclusive of bridge structures. This research aims at evaluating the seismic performance of the existing R/C bridge piers, which were nonseismically or seismically designed in accordance with the provision of Korea Highway Design Specification. Further experimental investigations have been doing to figure out the retrofitting effects of nonseismic R/C bridge piers confined with glass fiber at the plastic hinge zone. Pseudo-dynamic tests have been carried out in nine scaled R/C column specimens to investigate their hysteretic behavior under earthquake loading. Test parameters are axial load, input ground motion confinement steel ratio, glass fiber and etc.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.15-19
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• 2009

Due to the Japan's Kobe earthquake in 1995, a cut-and-cover tunnel, which is one of subway facilities, collapsed unexpectedly. As a result, also in Korea, seismic performance needs to be secured for the cut-and-cover tunnel and currently, the subway seismic design standard is based on the seismic performance. However, there is no standard for the damage level or stability level of a member for securing the seismic performance, and the definition of multi-level seismic performance is not sufficient. By contrast to this situation, in the Japan's evaluation method of seismic performance, design earthquake ground motion having reflected there into the subway driving stability is clearly defined and the seismic performance required for structures is classified in detail. This study analyzes the Japan's systematic evaluation method of seismic performance for cut-and-cover tunnels of subway.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.220-223
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• 2008

Many structural engineers believed that RC underground structures like subway system might not be seriously damaged during earthquakes, until the Great Hanshin earthquake(a.k.a Kobe earthquake). But there is only one domestic seismic code of rapid transit system that established by Ministry of Construction & Transportation in 2005. Therefore, to investigate of current status on seismic design and evaluation method of rapid transit system is essential to estimate seismic performance of subway structural systems. In this study, comparing domestic codes and seismic evaluation methods with foreign system is performed.

• Steel and Composite Structures
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• v.17 no.5
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• pp.687-704
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• 2014

A great number of moment-resisting steel structures collapsed due to ductile crack initiation at welded beam-column connections, followed by explosive brittle fracture in the Kobe (Hyogoken-Nanbu) earthquake in 1995. A series of experimental and numerical studies on cracking behaviors of beam-column connections in steel bridge piers were carried out by the authors' team. This paper aims to study the effect of post weld treatment on cracking behaviors of the connections during a strong earthquake event. Experiments of three specimens with different weld finishes, i.e., as-welded, R-finish, and burr grinding, were conducted. The experimental results indicate that the instants of ductile crack initiation are greatly delayed for the specimens with R-finish and burr grinding finishes compared with the as-welded one. The strain concentration effect in the connection is also greatly reduced in the specimens with post weld treatment compared with the as-welded one, which was also verified in the tests.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.11
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• pp.787-797
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• 2015

In this paper, a cochlea-inspired artificial filter bank(CAFB) was developed in order to efficiently acquire dynamic response of structure, and it was also evaluated via dynamic response experiments. To sort out signals containing significant modal information from all the dynamic responses of structure, it was made to adopt a band-pass filter optimizing algorithm(BOA) and a peak-picking algorithm (PPA). Optimally designed on the basis of El-centro and Kobe earthquake signals, it was then embedded into the wireless multi-measurement system(WiMMS). In order to evaluate the performance of the developed CAFB, a vibration test was conducted using the El-centro and Kobe earthquake signals, and structural responses of a two-span bridge were obtained and analyzed simultaneously by both a wired measurement system and a CAFB-based WiMMS. The test results showed that the compressed dynamic responses acquired by the CAFB-based WiMMS matched with those of the wired system, and they included significant modal information of the two-span bridge. Therefore this study showed that the developed CAFB could be used as a new, economic, and efficient measurement device for wireless sensor networks(WSNs) based real time structural health monitoring because it could reconstruct the whole dynamic response using the compressed dynamic response with significant modal information.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.61-70
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• 1999

Cracking was observed in beam-to-column connections of many steel building frames during the 1994 Northridge and 1995 Kobe earthquakes. Thus extensive experimental researches are currently being conducted to improve the seismic performance of steel frames. A value of 0.015 radian was considered as a reasonable estimate of beam plastic rotation demand in steel moment-resisting frames subjected to severe earthquakes. The objective of this research is to develop a type of connection detail which moves the plastic hinge region in the beam away from the face of the column and can prevent cracking at the welded flange of the beam-to-column connection under seismic loading. An experimental investigation was undertaken on five beam-to-column connection specimens to study the performance of the connections with proposed details. The experiemental results showed that the flexural strength and rotational ductility of the beam connections were adequate for the seismic resistance steel frames to prevent possible cracks at the connections.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.99-105
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• 2011

When a certain magnitude earthquake occurs, serious damage for human and properties is a major concern for most of the subway stations which were not applied for earthquake resistant design. Consideration and experimental verification for ground and structural behavior based on soil-structure interaction relation are required to evaluate seismic performance of the subway station as embedded structures. For 1/60 scaled subway station model, centrifuge modeling shaking table test is performed using Kobe and Northridge earthquakes. Compare to displacements and moments of the underground and structure obtained by soil response analysis and response displacement method based on experimental results, this paper shows how to evaluate seismic performance of subway station.