• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.98-107
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• 2000

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the ground response analysis In this study, ground response analyses based on the equivalent linear method were carried out to evaluate the effects of various ground conditions on the site amplification. Four major factors including the depth of the site(very soft and dense soil), the impedance ratio between soil layer and bed rock, linear analysis versus equivalent linear analysis, and the location of soft soil layer were deeply discussed. Based on the analysis results, the importance of various local site conditions on the site amplification was emphasized.

• Wind and Structures
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• 제38권3호
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• pp.193-202
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• 2024

Modern high-rise tower designs incorporating recessed balcony cavity spaces can be prone to high-frequency and narrow-band Rossiter aerodynamic excitations under glancing incident winds that can harmonize and compete with recessed balcony volume acoustic Helmholtz modes and facade elastic responses. Resulting resonant inertial wind loading to balcony facades responding to these excitations is additive to the peak design wind pressures currently allowed for in wind codes and can present as excessive facade vibrations and sub-audible throbbing in the serviceability range of wind speeds. This paper presents a methodology to determine Cavity Amplification Factors to account for façade resonant inertial wind loads resulting from balcony cavity aero-acoustic-elastic resonances by drawing upon field observations and the results of full-scale monitoring and model-scale wind tunnel tests. Recessed balcony cavities with single orifice type openings and located within curved façade tower geometries appear particularly prone. A Cavity Amplification Factor of 1.8 is calculated in one example representing almost a doubling of local façade design wind pressures. Balcony façade and tower design recommendations to mitigate wind induced aero-acoustic-elastic resonances are provided.

• 한국도로학회논문집
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• 제14권2호
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• pp.29-36
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• 2012

다양한 종류의 차량하중을 대상으로 도로의 평탄성과 차량의 속도가 도로에 작용하는 동적하중에 미치는 영향을 분석하기 위하여 경인고속도로의 교통량자료 분석을 통하여 통과빈도가 높은 대표 중차량 개념의 2축, 3축, 4축 그리고 5축 차량을 선정하였다. 선정된 대표 중차량을 대상으로 도로의 평탄성과 주행차량의 속도에 따른 동적 축하중을 TruckSim 프로그램을 통하여 산정한 후, 각 대표 중차량을 대상으로 도로 평탄성 변화에 따른 동적하중에 대한 정적하중의 비인 동적하중 증가계수를 산정하였다. 본 연구를 통해 산정된 동적하중 증가계수로부터 예측한 동적하중은 3축 대표 중차량에서 IRI가 3.5이고 주행차량 속도가 100km/h일 때 정적하중에 비해 최대 36%에 해당하는 추가적인 동적하중이 가해지는 것으로 나타났고, 다양한 차종에 대한 동적하중 증가계수의 특성을 분석한 결과 축간거리가 짧고 각 축에 가해지는 하중분담률이 높을수록 동적하중 증가계수가 증가함을 알 수 있었다.

• 한국강구조학회 논문집
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• 제22권1호
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• pp.87-97
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• 2010

본 연구는 비대칭 비가새 골조를 대상으로 강구조 설계기준에서 제시하고 있는 하중증폭계수를 적용한 2차 해석법의 타당성을 해석적 방법을 통해 평가하는데 그 목적이 있다. 이를 위해 KBC 2005에서 제안하고 있는 B1 및 B2 계수를 적용한 2차 해석과 KBC 2009에서 제안하고 있는 하중증폭계수를 적용한 직접해석을 5층 2스팬 및 5층 4스팬 비대칭 비가새 강구조 골조에 대해 실시하고, 그 해석 결과를 2차 비탄성 해석 결과와 비교하여 기준에서 제안된 2차 해석법들을 평가하였다. 해석의 주요 변수로는 골조 형상, 기둥 축력비, 해석방법, 기둥수평위치 등이 적용되었다. 연구 결과 구조물의 비대칭성은 B2 계수 및 제안된 해석법의 유효성에 영향을 미치는 것으로 나타났으며, 특히 기둥삭제 및 경사 기둥의 경우 오차의 범위가 증가하는 것으로 나타났다.

• Earthquakes and Structures
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• 제12권6호
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• pp.713-723
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• 2017

Steel plate shear walls (SPSWs) are effective lateral systems which have high initial stiffness, appropriate ductility and energy dissipation capability. Recently, steel plate shear walls with low yield point strength (LYP), were introduced and they attracted the attention of designers. Structures with this new system, besides using less steel, are more stable. In the present study, the effects of plates with low yield strength on the seismic design parameters of steel frames with steel plate shear walls are investigated. For this purpose, a variety of this kind of structures with different heights including the 2, 5, 10, 14 and 18-story buildings are designed based on the AISC seismic provisions. The structures are modeled using ANSYS finite element software and subjected to monotonic lateral loading. Parameters such as ductility (${\mu}$), ductility reduction ($R_{\mu}$), over-strength (${\Omega}_0$), displacement amplification ($C_d$) and behavior factor (R) of these structures are evaluated by carrying out the pushover analysis. Analysis results indicate that the ductility, over-strength and behavior factors decrease by increasing the number of stories. Also, the displacement amplification factor decreases by increasing the number of stories. Finally, the results were compared with the suggestions provided in the AISC code for steel plate shear walls. The results indicate that the values for over-strength, behavior and displacement amplification factors of LYP steel plate shear wall systems, are larger than those proposed by the AISC code for typical steel plate shear wall systems.

• Earthquakes and Structures
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• 제15권1호
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• pp.1-8
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• 2018

A new site classification system and site coefficients based on local site conditions in Korea were developed and implemented as a part of minimum design load requirements for general seismic design. The new site classification system adopted bedrock depth and average shear wave velocity of soil above the bedrock as parameters for site classification. These code provisions were passed through a public hearing process before it was enacted. The public hearing process recommended to modify the naming of site classes and adjust the amplification factors so that the level of short-period amplification is suitable for economical seismic design. In this paper, the new code provisions were assessed using dynamic centrifuge tests and by comparing the design response spectra (DRS) with records from 2016 Gyeongju earthquake, the largest earthquake in history of instrumental seismic observation in Korea. The dynamic centrifuge tests were performed to simulate the representative Korean site conditions, such as shallow depth to bedrock and short-period amplification characteristics, and the results corroborated with the new DRS. The Gyeongju earthquake records also showed good agreement with the DRS. In summary, the new code provisions are reliable for representing the site amplification characteristic of shallow bedrock condition in Korea.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1169-1175
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• 2019

The minimum detectable activity (MDA) value was derived according to the flow rate of the sample and degree of amplification of the device by sending the sample directly from the collection site to the detection part through a pump. This method can lead to reduction in time and cost compared to the existing measurement method that uses a pre-treatment process. In this study, experiments were conducted on $^3H$ and $^{90}Sr$, which are the major pure beta-emitting radionuclides, by setting the sample flow rate and the amplification gain as factors. The MDA values were derived according to the flow rates, considering that the flow rate can affect the MDA values. There were no change in the MDA under different flow rates of 0, 600, 800, and 1000 mL/min. Therefore, it was confirmed that the flow rate may not be considered when collecting samples for monitoring in actual field. As the degree of amplification of the amplifier increased, the time required to reach the target MDA decreased. When the amplification was quadrupled, the detection efficiency increased by approximately 23.4 times, and the time to reach the MDA decreased to approximately 1/550 times. This method offers the advantage of real-time on-site monitoring.

• Interaction and multiscale mechanics
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• 제3권4호
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• pp.389-403
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• 2010

Based on the Model Coupled Method (MCM), a case study has been carried out on a Concrete-Filled Steel Tubular (CFST) tied arch bridge to investigate the vibration problem. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements, and the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees-of-freedom. A well-known power spectral density of road pavement profiles defined the road surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated, and the dynamic amplification factors were computed for displacement and internal force. The impact effects of the vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some of the components were analyzed in the frequency domain. From the results some valuable conclusions have been drawn.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.8-14
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• 1997

The dynamic responses of highway bridges are varying depending on the features of either traveling vehicles or bridges. In this study, the probabilistic characteristics of dynamic amplification factors of highway bridges due to traveling heavy vehicles have been examined through analytical simulation processes. The truck with tandem axle and tractor with semitrailer are selected as the representative heavy vehicles, which are modeled with three dimensional 7-DOF and 12-DOF models, respectively. The analytical results have been compared with the experimental results of dynamic loading tests and the validity of the analytical models has been examined. Parametric studies on the means and extreme values of amplification factors have been performed with various traffic conditions such as vehicle types, vehicle weights, surface profiles, vehicle velocity, etc.

• Steel and Composite Structures
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• 제33권4호
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• pp.525-535
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• 2019

The seismic performance of steel frames equipped with a particular type of bending dissipative braces (BDBs) having U elements, which has recently been introduced and tested by the authors, is investigated. For this purpose, two structural systems, i.e., simple and dual steel building frames, both with diagonal BDBs and different number of stories, are considered. After providing a design method of this new BDB, the detailed structural models are developed in the OpenSees platform to perform nonlinear dynamic analyses. Seismic performance factors like ductility, overstrength, response modification and deflection amplification factors are calculated using incremental dynamic analysis (IDA). In addition, to assess the damage probability of the structural models, their seismic fragilities are developed. The results show high energy dissipation capacity of both structural systems while the number of U elements needed for the bracing system of each story in the moment frames are less than those in the corresponding non-moment (simple) frames. The average response modification and deflection amplification factors for both structural schemes are obtained about 8.6 and 5.4, respectively, which are slightly larger than the corresponding recommended values of ASCE for the typical buckling-restrained braces (BRBs).