• Earthquakes and Structures
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• v.4 no.6
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• pp.629-647
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• 2013

Loading protocols have been developed for quasi-static cyclic testing of structures and components. However, it is uncertain if protocols developed for conditions of intense ground shaking in regions of high seismicity would also be applicable to regions of low-moderate seismicity that are remote from the tectonic plate boundaries. This study presents a methodology for developing a quasi-static cyclic displacement loading protocol for experimental bracing evaluation of cold-formed steel stud shear walls. Simulations presented in the paper were based on conditions of moderate ground shaking (in Australia). The methodologies presented are generic in nature and can be applied to other regions of similar seismicity conditions (which include many parts of China, Korea, India and Malaysia). Numerous response time histories including both linear and nonlinear analyses have been generated for selected earthquake scenarios and site classes. Rain-flow cycle counting method has been used for determining the number of cycles at various ranges of normalized displacement amplitude. It is found that the number of displacement cycles of the loading protocol increases with increasing intensity of ground shaking (associated with a longer return period).

• Steel and Composite Structures
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• v.14 no.2
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• pp.155-171
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• 2013

This study analytically evaluated the seismic performance of wind-designed diagrid tall steel buildings in regions of moderate/low seismicity and strong winds. To this end, diagrid tall steel buildings with varying wind exposure and slenderness ratio (building height-to-width ratio) conditions were designed to satisfy the wind serviceability criteria specified in the Korean Building Code and the National Building Code of Canada. A series of seismic analyses were then performed for earthquakes having 43- and 2475- year return periods utilizing the design guidelines of tall buildings. The analyses demonstrated the good seismic performance of these wind-designed diagrid tall steel buildings, which arises because significant overstrength of the diagrid system occurs in the wind design procedure. Also, analysis showed that the elastic seismic design process of diagrid tall steel buildings might be accepted based on some wind exposures and slenderness ratios.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.13-20
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• 2013

In order to reduce seismic responses of a structure, additional dampers and vibration control devices are generally considered. Usually, control performance of additional devices are investigated for optimal design without variation of characteristics of a structure. In this study, multi-objective integrated optimization of structure-smart control device is conducted and possibility of reduction of structural resources of a building structure with smart top-story isolation system has been investigated. To this end, 20-story example building structure was selected and an MR damper and low damping elastomeric bearings were used to compose a smart base isolation system. Artificial earthquakes generated based on design spectrum of low-to-moderate seismicity regions are used for structural analyses. Based on numerical simulation results, it has been shown that a smart top-story isolation system can effectively reduce both structural responses and isolation story drifts of the building structure in low-to-moderate seismicity regions. The integrated optimal design method proposed in this study can provide various optimal designs that presents good control performance by appropriately reducing the amount of structural material and damping device.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.101-104
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• 2005

This study is to develop detailing guidelines based on ductility demand for reinforced concrete bridge columns in areas of low to moderate seismicity. The current seismic design criteria of the Korea Design Specifications for Highway Bridge (KDSHB 2005) adopted the seismic design concept and requirements of the AASHTO specifications. In order to obtain full ductile behavior under seismic loads, i.e. when applied seismic force is larger than design flexural strength of column section, a response modification factor (R=3 or 5) is used. In moderate seismicity regions, however, adopting the full ductility design concept sometimes results in construction problems due to reinforcement congestion. The objective of this paper is to suggest a new simplified seismic design of reinforced concrete bridge columns for moderate seismicity regions.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.5
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• pp.247-256
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• 2015

This paper briefly introduces the design seismic loads in Korea (KBC 2009). Then, over 10,000 recorded earthquake ground accelerograms, with their magnitude ranging from 4.0 to 8.0 and their epicentral distance ranging from 0 to 200 km, were used to examine the appropriateness of seismic load defined in Korea known as a low-to-moderate seismicity region. The following conclusions are drawn based on the results: (1) The effective peak ground accelerations (EPA) of recorded earthquake accelerograms under $M{\leq}6.0$ and $R{\geq}15km$ appear to be less than that of MCE in Korea for all site conditions defined in KBC 2009. (2) The design spectrum (two-thirds of the intensity of MCE) in KBC 2009 is comparable to those of earthquake records in the magnitude 6 - 7 and the epicentral distance less than 50 km. Therefore, (3) the intensity of Korean design earthquake is considered to be overly high since the Korea peninsula is generally conceived to be a low-seismicity region.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.155-162
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• 2002

A technique for the seismic reliability evaluation of electric power transmission systems(EPTS) adapted to ground motion characteristics of Korea has been developed to evaluate reliability indices corresponding to the whole system and to each node within. A network model with nodes and links for EPTS has been established, and a seismic substation-fragility curve obtained from seismic fragilities of power system facilities has been derived. A point source model, the doubly truncated Gutenberg-Richter relationship, and earthquake intensity attenuation formula have been applied to simulate seismic events. Using Monte-Carlo simulation method, the seismic reliability of EPTS is evaluated and, it appeared that seismic effect on EPTS in low and moderate seismicity regions has to be considered.

• Structural Engineering and Mechanics
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• v.39 no.4
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• pp.559-578
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• 2011

In regions of high seismic risk, high-strength concrete (HSC) columns of tall buildings are designed to be fully ductile during earthquake attack by providing substantial amount of confining steel within the critical region. However. in areas of low to moderate seismic risk, the same provision of confining steel is too conservative because of the reduced seismic demand. More critically, it causes problematic steel congestion in the beam-column joints and column critical region. This will eventually affect the quality of concrete placing owing to blockage. To relieve the problem, the confining steel in the critical region of HSC columns located in low to moderate seismicity regions can be suitably reduced, while maintaining a limited ductility level. Despite the advantage, there are still no guidelines developed for designing limited ductility HSC columns. In this paper, a formula for designing limited ductility HSC columns is presented. The validity of the formula was verified by testing half-scale HSC columns subjected to combined high-axial load and flexure, in which the confining steel was provided as per the proposed formula. From the test results, it is evident that the curvature ductility factors obtained for all these columns were about 10, which is the generally accepted level of limited ductility.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.2
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• pp.77-86
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• 2018

This study develops an empirical prediction equation of spectral acceleration responses of earthquakes which can induce structural damages. Ground motion records representing hazards of low-to-moderate seismic regions were selected and organized with several influential factors affecting the response spectra. The empirical equation and estimator coefficients for acceleration response spectra were then proposed using a robust nonlinear optimization coupled with a regression analysis. For analytical verification of the prediction equation, response spectra used for low-to-moderate seismic regions were estimated and the predicted results were comparatively evaluated with measured response spectra. As a result, the predicted shapes of response spectra can simulate the graphical shapes of measured data with high accuracy and most of predicted results are distributed inside range of correlation of variation (COV) of 30% from perfectly correlated lines.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.305-312
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• 1999

A four-story reinforced concrete frame building model is designed for the gravity loads. only Static nonlinear pushover analyses are performed in two orthogonal horizontal directions. The overall capacity curves are converted into ADRS spectra and compared with demand spectra. At several points the deformed shape moment and shear distribution are calculated. It is observed that the seismic capacity may not meet the design requirements in soft soil condition and may collapse in MCE. It is concluded that limited but adequate amount of ductility need be provided in the seismic design in low to moderate seismicity regions.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.178-185
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• 1999

Minimum life-cycle cost helps to evaluate cost effectiveness of base-isolated bridges under specific condition. Life-cycle cost mainly consists of the initial construction cost and the expected damage cost. Damage cost estimation needs proper model of input ground motion failure probability evaluation method and limit states definition. We model the input ground motion as spectral density function compatible with the response spectra defined at each seismicity and site condition. Spectrum analysis and crossing theory is suitable for reseating calculation of failure probabilities in the process of cost minimization. Limit states of base-isolated bridges re defined for superstructure isolator and pier respectively The method is applied to both base-isolated bridges and conventional bridges under the same conditions to investigate cost effectiveness of base isolation in low and moderate seismic region. the results show that base-isolation of bridges are more effective in low and moderate seismic region and that the site effects on the economical efficiency may not be negligible in such a region.