• 한국지진공학회논문집
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• 제18권2호
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• pp.73-78
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• 2014

In this paper, the stochastic 1D site response analysis method using Monte Carlo simulation and considering thespatial variation of shear wave velocity profile isproposed. To consider thespatial variation of shear wave velocity profile for 1D site response analysis, the proposed method generates random shear wave velocity profiles representing the target site, and Monte Carlo simulation is used to calculate theprobability distribution of the site response analysis results such as thepeak ground acceleration. Through the field application, The applicability of the proposed method is verified through field application.

• Earthquakes and Structures
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• 제4권4호
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• 한국지반공학회논문집
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• 제36권10호
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• pp.41-56
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• 2020

지진 경보 시스템이 빠르고 정확하게 가동하기 위해서는 충분한 수량의 계측 시스템 확보와 더불어서 적절한 계측 데이터 해석기술 개발이 요구된다. 신규 지진계를 설치시 많은 비용이 소모되기 때문에, 열차 내 가속도계 등을 대체재로 지진 경보 시스템에 활용하는 것이 효율적이다. 그러나 열차에 설치된 가속도계의 경우, 지진계와는 달리 열차 주행시 진동 데이터가 포함되어 있다. 또한, 지진 발생시 성토구간에 의해서 변화된 지진응답을 계측하게 된다. 본 연구에서는 위의 특성들이 포함된 열차 가속도계 데이터에 기반한 지진감지 기술을 제안하고자 한다. 우선, 성토구간의 지진응답 해석기법을 활용하여 열차가 성토구간을 지날 때 지진이 발생하는 것을 구현한 가상의 열차 가속도 데이터를 구축하였다. 구축한 가속도 데이터를 Short time Fourier Transform(STFT)와 Wavelet Transform(WT)을 활용하여 시간-주파수 분석을 수행하였다. 분석 결과, STFT가 장주기 지진 감지에 적합한 반면, WT의 경우 단주기 지진 감지에 유용함을 확인하였다.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.51-69
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• 2001

Whereas the potential of static inelastic analysis methods is recognised in earthquake design and assessment, especially in contrast with elastic analysis under scaled forces, they have inherent shortcomings. In this paper, critical issues in the application of inelastic static (pushover) analysis are discussed and their effect on the obtained results appraised. Areas of possible developments that would render the method more applicable to the prediction of dynamic response are explored. New developments towards a fully adaptive pushover method accounting for spread of inelasticity, geometric nonlinearity, full multi-modal, spectral amplification and period elongation, within a framework of fibre modelling of materials, are discussed and preliminary results are given. These developments lead to static analysis results that are closer than ever to inelastic time-history analysis. It is concluded that there is great scope for improvements of this simple and powerful technique that would increase confidence in its employment as the primary tool for seismic analysis in practice.

• Steel and Composite Structures
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• 제26권2호
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• pp.197-211
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• 2018

The study presents the earthquake performance of the Bosphorus Bridge under multi-point earthquake excitation considering the spatially varying site-specific earthquake motions. The elaborate FE model of the bridge is firstly established depending on the new considerations of the used FEM software specifications, such as cable-sag effect, rigid link and gap elements. The modal analysis showed that singular modes of the deck and the tower were relatively effective in the dynamic behavior of the bridge due to higher total mass participation mass ratio of 80%. The parameters and requirements to be considered in simulation process are determined to generate the spatially varying site-specific ground motions. Total number of twelve simulated ground motions are defined for the multi-support earthquake analysis (Mp-sup). In order to easily implement multi-point earthquake excitation to the bridge, the practice-oriented procedure is summarized. The results demonstrated that the Mp-sup led to high increase in sectional forces of the critical components of the bridge, especially tower base section and tensile force of the main and back stay cables. A close relationship between the dynamic response and the behavior of the bridge under the Mp-sup was also obtained. Consequently, the outcomes from this study underscored the importance of the utilization of the multi-point earthquake analysis and the necessity of considering specifically generated earthquake motions for suspension bridges.

• Earthquakes and Structures
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• 제10권6호
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• pp.1331-1346
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• 2016

Historical masonry structures have an important value for cultures and it is essential for every society to strengthen them and confidently transfer to the future. For this reason, determination of the seismic earthquake response, which is the most affecting factor to cause the damage at these structures, gain more importance. In this paper, the seismic earthquake behaviour of Kaya Çelebi Mosque, which is located in Turkey and the restoration process has still continued after 2011 Van earthquake, is determined. Firstly the dynamic modal analysis and subsequently the seismic spectral analysis are performed using the finite element model of the mosque constructed with restoration drawings in SAP2000 program. Maximum displacements, tensile, compressive and shear stresses are obtained and presented with contours diagrams. Turkish Earthquake Code and its general technical specifications are considered to evaluate the structural responses. After the analyses, it is seen that the displacements and compressive/shear stresses within the code limits. However, tension stresses exceeded the maximum values at some local regions. For this mosque, this is in tolerance limits considering the whole structure. But, it can be said that the tension stresses is very important for this type of the structures, especially between the stone and mortar. So, some additional strengthening solutions considering the originality of historical structures may be applicable on maximum tensile regions.

• Earthquakes and Structures
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• 제17권1호
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• pp.75-89
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• 2019

The paper presents experimental and numerical studies carried out on low-rise RC frames, typically found in developing countries. Shake table tests were conducted on 1:3 reduced scaled two-story RC frames that included a code conforming SMRF model and another non-compliant model. The later was similar to the code conforming model, except, it was prepared in concrete having strength 33% lower than the design specified, which is commonly found in the region. The models were tested on shake table, through multiple excitations, using acceleration time history of 1994 Northridge earthquake, which was linearly scaled for multi-levels excitations in order to study the structures' damage mechanism and measure the structural response. A representative numerical model was prepared in finite element based program SeismoStruct, simulating the observed local damage mechanisms (bar-slip and joint shear hinging), for seismic analysis of RC frames having weaker beam-column joints. A suite of spectrum compatible acceleration records was obtained from PEER for incremental dynamic analysis of considered RC frames. The seismic performance of considered RC frames was quantified in terms of seismic response parameters (seismic response modification, overstrength and displacement amplification factors), for critical comparison.

• Structural Monitoring and Maintenance
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• 제9권2호
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• pp.107-127
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• 2022

Structural health monitoring (SHM) has been related to damage identification with either operational loads or other environmental loading playing a significant complimentary role in terms of structural safety. In this study, a non-parametric method of time frequency analysis on the measurement is used to address the time-frequency representation for modal parameter estimation and system damage identification of structure. The method employs the wavelet decomposition of dynamic data by using the modified complex Morlet wavelet with variable central frequency (MCMW+VCF). Through detail discussion on the selection of model parameter in wavelet analysis, the method is applied to study the dynamic response of both steel structure and reinforced concrete frame under white noise excitation as well as earthquake excitation from shaking table test. Application of the method to building earthquake response measurement is also examined. It is shown that by using the spectrogram generated from MCMW+VCF method, with suitable selected model parameter, one can clearly identify the time-varying modal frequency of the reinforced concrete structure under earthquake excitation. Discussions on the advantages and disadvantages of the method through field experiments are also presented.

• 한국지진공학회논문집
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• 제12권6호
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• pp.55-63
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• 2008

본 연구에서는 지반-구조물 상호작용을 고려한3차원 지반-구조계의 지진응답 해석을 수행하고 그 기법의 적용성과 타당성을 검토한다. 이를 위해 구조물과 구조물 주변의 근역지반을3차원 유한요소로서 모델링하고 원역지반에 대해서는 기 개발한 3차원 동적 무한요소를 적용한다. 모든 입사 성분P, SV 그리고 SH파가 고려되었을 때, 등가 지진하중은 무한요소에 의해 구해진 무한 지반의 동적 강성과 자유장 해석을 통해 구해진 지반의 응력과 변위응답을 이용하여 구해진다. 검증 및 적용 예제는 적층 자유장의 지반응답해석과 전형적 원자로 격납건물의 지반-구조물 상호작용을 고려한 층응답 스펙트럼을 구하는 것으로 하였다. 해석 결과는 다른 기법에 의해 구해진 값들과 비교하였으며, 본 기법의 정확성과 정밀성을 확인할 수 있다.

• 한국지진공학회논문집
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• 제7권1호
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• pp.57-63
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• 2003

현수교의 지진응답 산정 시 몇 가지 해석법 간에 발생될 수 있는 차이를 파악하고자 하나의 예제 현수교에 대해 비교 연구를 수행하였다. 주된 검토항목은 선형과 비선형 응답응답스펙트럼법과 동적해석법, 그리고 감쇠율과 감쇠고려 방안이다. 검토 결과 대상 물리량이나 가진 방향에 따라 약간의 차이는 있지만 전체적으로 감쇠율과 감쇠 고려방안 등 감쇠와 관련된 변수가 지진응답에 큰 영향을 미치고 있음을 확인하였다. 반면 응답스펙트럼과 동적해석법, 선형 및 비선형해석법 등 구조해석법에 관련된 변수는 상대적으로 지진응답에 미치는 영향이 적은 것으로 확인되었다. 대상 현수교의 경우에도 응답스펙트럼법이 안전측의 결과를 줄 수 있을 것으로 기대되지만 이 경우 도로교설계기준에 제시된 설계응답스펙트럼을 감쇠율에 따라 적절히 보정하는 사전 작업이 필요랄 것으로 판단되었다.