• 지질공학
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• 제26권2호
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• pp.177-185
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• 2016

고분해능 시추공 변형률계로부터 측정된 변형 신호를 이용하여 지진에 의한 응력 변화 해석의 가능성에 대해 고찰하였다. 응력 변화 분석을 위해 2010년 4월 4일 발생한 El Mayor-Cucapah 지진(M_w=7.2)에 의한 변형 신호가 기록된 자료를 이용하여 주압축응력 방향과 크기를 산정하였다. 분석 결과는 지진 전후의 응력 변화 양상에 대한 차이점과 지진 발생과 동시에 특징적인 응력 변화 양상을 보였다. 지진 발생 전후 응력 방향 변화는 지진 해로 규명되는 최대주응력 방향에서의 응력 증가와 연관성이 있는 것으로 해석된다. 지진 발생 시 응력 크기 변화는 주방향에서 10⁻³-10⁻² MPa 수준의 응력 급상승, 하강으로 나타났다. 산정된 응력 크기 변화량에 대한 검증을 위해 지진과 관련된 매개변수를 이용하여 응력 전파를 모사할 수 있는 쿨롱 응력 전파 모델링을 실시하였다. 시추공 측정 결과로부터 계산된 전단응력 변화량은 (0.3-0.8) × 10⁻²MPa의 증가가 있었으며 이는 쿨롱 응력 전파 모델을 통해 얻어진 전단응력 증가량 (0.1-0.6) × 10⁻²MPa과 상당히 유사함을 확인하였다. 따라서 시추공 변형률계 자료가 설치 지역에서 작용하는 주응력의 영향과 지진에 의해 변화하는 응력 변화를 충분히 반영하고 있음을 시사하며 시추공 변형률계 자료로부터 얻어지는 유의미한 응력 정보는 지진 관련 연구에서 활용될 수 있을 것으로 기대한다.

• Structural Engineering and Mechanics
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• 제32권5호
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• pp.587-608
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• 2009

Modern earthquake-resistant design aims to isolate architectural precast concrete panels from the structural system so as to reduce the interaction with the supporting structure and hence minimize damage. The present study seeks to maximize the cladding-structure interaction by developing an energy-dissipating cladding system (EDCS) that is capable of functioning both as a structural brace, as well as a source of energy dissipation. The EDCS is designed to provide added stiffness and damping to buildings with steel moment resisting frames with the goal of favorably modifying the building response to earthquake-induced forces without demanding any inelastic action and ductility from the basic lateral force resisting system. Because many modern building facades typically have continuous and large openings on top of the precast cladding panels at each floor level for window system, the present study focuses on spandrel type precast concrete cladding panel. The preliminary design of the EDCS was based on existing guidelines and research data on architectural precast concrete cladding and supplemental energy dissipation devices. For the component-level study, the preliminary design was validated and further refined based on the results of nonlinear finite element analyses. The stiffness and strength characteristics of the EDCS were established from a series of nonlinear finite element analyses and are discussed in detail in this paper.

• Earthquakes and Structures
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• 제5권2호
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• pp.225-237
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• 2013

Excessive vibrations induced by earthquake excitation and wind load are an obstacle in design and construction of tall and super tall buildings. An innovative vibration control structure system (Mega-Sub Controlled Structure System-MSCSS) was recently proposed to further improve humans comfort and their safeties during natural disasters. Preliminary investigations were performed using a two dimensional equivalent simplified model, composed by 3 mega-stories. In this paper, a more reasonable and realistic scaled model is design to investigate the dynamical characteristics and controlling performances of this structure when subjected to strong earthquake motion. The control parameters of the structure system, such as the modulated sub-structures disposition; the damping coefficient ratio (RC); the stiffness ratio (RD); the mass ratio of the mega-structure and sub-structure (RM) are investigated and their optimal values (matched values) are obtained. The MSCSS is also compared with the so-called Mega-Sub Structure (MSS) regarding their displacement and acceleration responses when subjected to the same load conditions. Through the nonlinear time history analysis, the effectiveness and the feasibility of the proposed mega-sub controlled structure system (MSCSS) is demonstrated in reducing the displacement and acceleration responses and also improving human comfort under earthquake loads.

• Steel and Composite Structures
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• 제37권4호
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• pp.463-479
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• 2020

Currently, there are many lateral resisting systems utilized in resisting lateral loads being produced in an earthquake. Such systems can significantly reduce the roof's displacement when placed at an optimum location. Since in the design of tall buildings, the minimum distance between adjacent buildings is important. In this paper, the critical excitation method is used to determine the best location of the belt truss system while calculating the minimum required distance between two adjacent buildings. For this purpose, the belt truss system is placed at a specific story. Then the critical earthquakes are computed so that the considered constraints are satisfied, and the value of roof displacement is maximized. This procedure is repeated for all stories; i.e., for each, a critical acceleration is computed. From this set of computed roof displacement values, the story with the least displacement is selected as the best location for the belt truss system. Numerical studies demonstrate that absolute roof displacements induced through critical accelerations range between 5.36 to 1.95 times of the San Fernando earthquake for the first example and 7.67 to 1.22 times of the San Fernando earthquake for the second example. This method can also be used to determine the minimum required distance between two adjacent buildings to eliminate the pounding effects. For this purpose, this value is computed based on different standard codes and compared with the results of the critical excitation method to show the ability of the proposed method.

• Structural Engineering and Mechanics
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• 제8권4호
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• pp.361-382
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• 1999

This paper reviews aspects of current design procedures for seismic design of structures, and specifically examines their relevance to the design of light framed residential buildings under earthquake loading. The significance of the various structural contributions made by the components of cold formed steel framed residential structures subjected to earthquake induced loadings has been investigated. This is a common form of residential construction worldwide. Particular attention is given to aspects related to ductility and overstrength, the latter arising principally from the contributions of the designated "non-structural" components. Based on both analytical and experimental data obtained from research investigations on steel framed residential structures, typical ranges of the ductility reduction factor and overstrength ratios are determined. It is concluded that the latter parameter has a very significant influence on the seismic design of such structures. Although the numerical ranges for the inelastic seismic parameters given in this paper were obtained for Australian houses, the concepts and the highlighted aspects of seismic design methodology are more widely applicable.

• Structural Engineering and Mechanics
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• 제51권6호
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• pp.909-922
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• 2014

In this paper, we present an alternative seismic design strategy for cable stayed bridges with concrete pylons when subjected to strong ground motions. The comparison of conventional seismic design using supplemental dampers (strategy A) and the new strategy using nonlinear seismic design of pylon columns (strategy B) is exemplified by one typical medium span cable stayed bridge subjected to strong ground motions from 1999 Taiwan Chi-Chi earthquake and 2008 China Wenchuan earthquake. We first conducted the optimization of damper parameters according to strategy A in response to the distinct features that strong ground motions contain. And then we adopted strategy B to carry out seismic analysis by introducing the elastic-plastic elements that allowing plasticity development in the pylon columns. The numerical results show that via strategy A, the earthquake induced structural responses can be kept in the desired range provided with the proper damping parameters, however, the extra cost of unusual dampers will be inevitable. For strategy B, the pylon columns may not remain elastic and certain plasticity developed, but the seismic responses of the foundation will be greatly decreased, meanwhile, the displacement at the top of pylon seems to be not affected much by the yielding of pylon columns, which indicates the pylon nonlinear design can be an alternative design strategy when strong ground motions have to be considered for the bridge.

• 지구물리
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• 제7권3호
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• pp.185-192
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• 2004

2001년 1월부터 2004년 2월까지 한반도 남부 지역에서 발생한 지진의 모멘트규모를 계산하여 기상청과 한국지질자원연구원의 지역규모와의 관계를 분석하였다 분석 결과 기상청의 지역규모는 한국지질자원연구원의 지역규모에 비해 모멘트규모와의 상관성이 낮은 것으로 나타났다 또한 발표된 지역규모와 계산된 모멘트규모의 회귀 분석을 통해 모멘트규모 환산식을 유도하였다 유도된 모멘트규모 환산식은 지진목록의 규모 단일화에 이용될 수 있고 규모가 단일화된 지진목록은 지진활동 특성 분석 지진재해도나 감쇄식 등에 필요한 인자로서 활용될 수 있다

• Structural Engineering and Mechanics
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• 제44권6호
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• pp.763-774
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• 2012

Reinforced concrete frame structures with masonry infill walls constitute the significant portion of the building stock in Turkey. Therefore it is very important to understand the behavior of masonry infill frame structures under earthquake loads. This study presents an experimental work performed on reinforced concrete (RC) frames with different types of masonry infills, namely standard and locked bricks. Earthquake effects are induced on the RC frames by quasi-static tests. Results obtained from different frames are compared with each other through various stiffness, strength, and energy related parameters. It is shown that locked bricks may prove useful in decreasing the problems related to horizontal and vertical irregularities defined in building codes. Moreover tests show that locked brick infills maintain their integrity up to very high drift levels, showing that they may have a potential in reducing injuries and fatalities related to falling hazards during severe ground shakings.

• Structural Engineering and Mechanics
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• 제36권4호
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• pp.481-497
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• 2010

The shaking table tests were conducted on two small-scale models (Model 1 and Model 2) to examine the earthquake-induced damage of a concrete gravity dam, which has been planned for the construction with the recommendation of the peak ground acceleration of the maximum credible earthquake of 0.42 g. This study deals with the numerical simulation of shaking table tests for two smallscale dam models. The plastic damage constitutive model is used to simulate the crack/damage behavior of the bentonite-concrete mixture material. The numerical results of the maximum failure acceleration and the crack/damage propagation are compared with experimental results. Numerical results of Model 1 showed similar crack/damage propagation pattern with experimental results, while for Model 2 the similar pattern was obtained by considering the modulus of elasticity of the first and second natural frequencies. The crack/damage initiated at the changing point in the downstream side and then propagated toward the upstream side. Crack/damage accumulation occurred in the neck area at acceleration amplitudes of around 0.55 g~0.60 g and 0.65 g~0.675 g for Model 1 and Model 2, respectively.

• 한국지진공학회논문집
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• 제13권4호
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• pp.37-45
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• 2009

구조 시스템을 구성하는 구조부재들의 상대적인 중요도를 판별하는 것은 성능기반 지진공학에서 매우 중요한 과정이다. 확률기법의 하나인 First-Order Second Moment 방법을 이용하여, 각 구조부재들의 불확실한 성능 때문에 발생하는 구조 시스템의 요구 성능의 불확실성을 예측할 수 있고, 이런 과정을 통해서 구조부재의 중요도를 판별할 수 있다. 특정한 구조부재의 불확실한 성능에 대한 구조 시스템의 요구성능이 민감할수록 그 구조부재의 중요도는 높아진다는 점을 이용하여 중요부재를 판별한다. 따라서 요구성능의 민감도가 상대적으로 큰 구조부재는 그렇지 않은 부재보다 더 중요하다고 할 수 있다. 개발된 중요부재 판별법은 연성 철근콘크리트 프레임의 중요부재를 판별하는 과정에 적용함으로써 방법을 검증하였고, 적용 가능성을 보여주었다.