• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.777-782
• /
• 2007

Displacement amplification factor can be used to estimate inelastic displacement demands from elastic displacement demands, The simple formula for displacement amplification factor considering hysteretic behavior of structural system and earthquake characteristics is proposed. And the effects of several parameters such as displacement ductility, strain hardening ratio, period, characteristics of earthquakes and hysteretic models for the displacement amplification factor are evaluated. Accuracy of the proposed formula is evaluated by comparing the displacement amplification factors estimated by existing and proposed formula with those calculated from inelastic time history analysis. The displacement amplification factors by proposed formulas provide a good agreement with those calculated by inelastic time history analysis.

• Steel and Composite Structures
• /
• 제37권1호
• /
• pp.91-98
• /
• 2020

Steel plate shear walls are recently used as efficient seismic lateral resisting systems. These lateral resistant structures are implemented to provide more strength, stiffness and ductility in limited space areas. In this study, the seismic behavior of the multi-story steel frames with steel plate shear walls are investigated for buildings with 4, 8, 12 and 16 stories using verified computational modeling platforms. Different number of steel moment bays with distinctive lengths are investigated to effectively determine the deflection amplification factor for low-rise and high-rise structures. Results showed that the dissipated energy in moment frames with steel plates are significantly related to the inside panel. It is shown that more than 50% of the dissipated energy under various ground motions is dissipated by the panel itself, and increasing the steel plate length leads to higher energy dissipation capability. The deflection amplification factor is studied in details for various verified parametric cases, and it is concluded that for a typical multi-story moment frame with steel plate shear walls, the amplification factor is 4.93 which is less than the recommended conservative values in the design codes. It is shown that the deflection amplification factor decreases if the height of the building increases, for which the frames with more than six stories would have less recommended deflection amplification factor. In addition, increasing the number of bays or decreasing the steel plate shear wall length leads to a reduction of the deflection amplification factor.

• Earthquakes and Structures
• /
• 제8권2호
• /
• pp.443-462
• /
• 2015

Some model building codes stipulate that the design displacement of a building can be computed using the elastic static analysis results multiplied by the deflection amplification factor, $C_d$. This approach for estimating the design displacement is essential and appealing in structural engineering practice when nonlinear response history analysis (NRHA) is not required. Furthermore, building codes stipulate the consideration of accidental torsion effects using accidental eccentricity, whether the buildings are symmetric-plan, or asymmetric-plan. In some model building codes, the accidental eccentricity is further amplified by the torsional amplification factor $A_x$ in order to minimize the discrepancy between statically and dynamically estimated responses. Therefore, this warrants exploration of the reliability of statically estimated design displacements in accordance with the building code requirements. This study uses the discrepancy curves as a way of assessing the reliability of the design displacement estimates resulting from the factors $C_d$ and $A_x$. The discrepancy curves show the exceedance probabilities of the differences between the statically estimated design displacements and NRHA results. The discrepancy curves of 3-story, 9-story, and 20-story example buildings are investigated in this study. The example buildings are steel special moment frames with frequency ratios equal to 0.7, 1.0, 1.3, and 1.6, as well as existing eccentricity ratios ranging from 0% to 30%.

• Structural Engineering and Mechanics
• /
• 제42권1호
• /
• pp.121-129
• /
• 2012

All contemporary seismic Codes have adopted smooth design acceleration response spectra, which have derived by statistical analysis of many elastic response spectra of natural accelerograms. The above smooth design spectra are characterized by two main branches, an horizontal branch that is 2.5 times higher than the peak ground acceleration, and a declining parabolic branch. According to Eurocode EN/1998, the period range of the horizontal, flat branch is extended from 0.1 s, for rock soils, up to 0.8 s for softer ones. However, from many natural recorded accelerograms of important earthquakes, the real spectral amplification factor appears to be much higher than 2.5 and this means that the spectrum leads to an unsafe seismic design of the structures. This point is an issue open to question and it is the object of the present study. In the present paper, the spectral amplification factor of the smooth design acceleration spectra is re-calculated on the grounds of a known "reliability index" for a desired probability of exceedance. As a pilot scheme, the seismic area of Greece is chosen, as it is the most seismically hazardous area in Europe. The accelerograms of the 82 most important earthquakes, which have occurred in Greece during the last 38 years, are used. The soil categories are taken into account according to EN/1998. The results that have been concluded from these data are compared with the results obtained from other strong earthquakes reported in the World literature.

• Steel and Composite Structures
• /
• 제21권5호
• /
• pp.1069-1084
• /
• 2016

This paper introduces a new and effective design amplification factor-based approach for reliable optimum design of trusses. This paper may be categorized as in the family of decoupled methods that aiming for a reliable optimum design based on a Design Amplification Factor (DAF). To reduce the computational expenses of reliability analysis, an improved version of Response Surface Method (RSM) was used. Having applied this approach to two planar and one spatial truss problems, it exhibited a satisfactory performance.

• 한국지진공학회논문집
• /
• 제24권3호
• /
• pp.123-128
• /
• 2020

Analysis of the 2016 Gyeongju earthquake and the 2017 Pohang earthquake showed the characteristics of a typical high-frequency earthquake with many high-frequency components, short time strong motion duration, and large peak ground acceleration relative to the magnitude of the earthquake. Domestic nuclear power plants were designed and evaluated based on NRC's Regulatory Guide 1.60 design response spectrum, which had a great deal of energy in the low-frequency range. Therefore, nuclear power plants should carry out seismic verification and seismic performance evaluation of systems, structures, and components by reflecting the domestic characteristics of earthquakes. In this study, high-frequency amplification factors that can be used for seismic verification and seismic performance evaluation of nuclear power plant systems, structures, and equipment were analyzed. In order to analyze the high-frequency amplification factor, five sets of seismic time history were generated, which were matched with the uniform hazard response spectrum to reflect the characteristics of domestic earthquake motion. The nuclear power plant was subjected to seismic analysis for the construction of the Korean standard nuclear power plant, OPR1000, which is a reactor building, an auxiliary building assembly, a component cooling water heat exchanger building, and an essential service water building. Based on the results of the seismic analysis, a high-frequency amplification factor was derived upon the calculation of the floor response spectrum of the important locations of nuclear power plants. The high-frequency amplification factor can be effectively used for the seismic verification and seismic performance evaluation of electric equipment which are sensitive to high-frequency earthquakes.

• 대한건축학회논문집:구조계
• /
• 제35권12호
• /
• pp.137-148
• /
• 2019

Korean piloti-type buildings are comprised of pilotis in the first story and shear walls in the upper stories. This vertical irregularity causes excessive lateral plastic deformation on the first story while the upper stories stay elastic. Meanwhile, asymmetric position of structural components such as core walls and columns of RC piloti-type buildings tends to produce torsional irregularities of the structures. Korean Building Code(KBC2016) requires the special seismic load and torsional amplification factor to apply to the piloti-type buildings lower than six-story or 20m if it has vertical and torsional irregularities when the building corresponds to seismic design category C or D. Many Korean low-rised RC buildings fall into the class. Therefore, the special earthquake load and torsional amplification factor are often applied to a building simultaneously. However, it has not been studied enough how much influence each parameter has on buildings with vertical and torsional irregularities at the same time. The purpose of this study is to evaluate the effect of factor special seismic load and torsional amplification on seismic performance of irregular buildings. In this study, a damaged 4^th story piloti-type building by the Pohang earthquake was selected and the earthquake response analysis was carried out with various seismic design methods by the KBC 2016. The effect of the design parameters on seismic performance was analyzed by the dynamic analysis of models with special seismic load and torsional amplification factor based on the selected building. It was concluded that the application of the torsional amplification factor to the reference model to which special seismic design was applied, does not significantly affect the seismic performance.

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

• Structural Engineering and Mechanics
• /
• 제84권2호
• /
• pp.155-165
• /
• 2022

The use of electricity and communication between electronic devices is increasing daily, which makes the stability of electrical power supply vital. Since the 1990s, large earthquakes have occurred frequently causing considerable direct damage to electrical power facilities as well as secondary damage, such as difficulty in restoring functions due to the interruption of electric power supply. Therefore, it is very important to establish measures to protect electrical power facilities, such as transformers and switchboards, from earthquakes. In this study, a 154 kV transformer whose service life had expired was installed on the base fabricated by simulating the field conditions and conducting the shaking table tests. The dynamic characteristics and seismic behavior of the 154 kV transformer were analyzed through the resonance frequency search test and seismic simulation test that considers the front, rear, left, and right directions. Since the purpose of this study is to analyze the acceleration amplification in the bushing due to the acceleration amplification, the experimental results were analyzed focusing on the acceleration response and the converted acceleration amplification ratio rather than the failure due to the displacement response of the transformer. The seismic force amplification at the transformer bushing was evaluated by simulating the characteristics of electrical power facilities in South Korea, and compared with the IEC TS 61463 acceleration amplification factor. Finally, the amplification factor at zero period acceleration (ZPA) modified for each return period was summarized. The results of this study can be used as data to define the amplification factor at ZPA of the transformer bushing, simulating the characteristics of electrical power facilities in Korea.

• 대한전기학회논문지
• /
• 제36권10호
• /
• pp.741-747
• /
• 1987

The high-power Nd:glass system with five-stage amplifier was designed and its amplification characteristics was studied for developing high-power Nd:glass laser system as an energy driver of inertial confinement fusion(ICF). In order to study the amplification characteristics of remporal and spacial Gaussian laser beam, the dependence of them on pumping efficiency and rod loss were studied and discussed. The output energy of this system using phosphate Nd glass rod(LHG-7,LHG-8) and silicate Nd glass rod(LSG-91H), respectively, was calculated by the computer simulation using Avizonis-Grotbeck and Frantz Nodvik equations. As results of this simulation, it was found that the shorter the risetime of laser pulse, the larger the amplification factor and that the larger peak value of laser pulse, the lower the amplification factor. The output inergies of 179J, 344J, and 7J were obtained by the designed five-stage amplified high-power Nd:glass laser system using glass rods of LHG-7,LHG-8, and LSG-91H, respectively. From the results it was found that the laser system using the LHG-8 glass rod was the most excellent one among the systems and the cross section for stimulated emission of the gain coefficient was essentially important parameter for the amplification characteristics.