• Earthquakes and Structures
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• v.8 no.5
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• pp.1255-1276
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• 2015

The importance of considering soil-structure interaction effect in the analysis and design of RC frame buildings is increasingly recognized but still not penetrated to the grass root level owing to various complexities involved. It is well established fact that the soil-structure interaction effect considerably influence the design of multi-storey buildings subjected to lateral seismic loads. The shear walls are often provided in such buildings to increase the lateral stability to resist seismic lateral loads. In the present work, the linear soil-structure analysis of a G+5 storey RC shear wall building frame resting on isolated column footings and supported by deformable soil is presented. The finite element modelling and analysis is carried out using ANSYS software under normal loads as well as under seismic loads. Various load combinations are considered as per IS-1893 (Part-1):2002. The interaction analysis is carried out with and without shear wall to investigate the effect of inclusion of shear wall on the total and differential settlements in the footings due to deformations in the soil mass. The frame and soil mass both are considered to behave in linear elastic manner. It is observed that the soil-structure interaction effect causes significant total and differential settlements in the footings. Maximum total settlement in footings occurs under vertical loads and inner footings settle more than outer footings creating a saucer shaped settlement profile of the footings. Each combination of seismic loads causes maximum differential settlement in one or more footings. Presence of shear wall decreases pulling/pushing effect of seismic forces on footings resulting in more stability to the structures.

• Earthquakes and Structures
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• v.10 no.2
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• pp.483-494
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• 2016

Historical structures that function as a bridge from past to present are the cultural and social reflections of societies. Masonry bridges are one of the important historical structures. These bridges are vulnerable against to seismic action. In this study, linear and non-linear dynamic analyses of historical Nadir Bridge are assessed. The bridge is modelled with three dimensional finite elements. For the seismic effect, artificial acceleration records are generated considering the seismic characteristics of the region where the bridge is located. Seismic response of the bridge is investigated.

• Earthquakes and Structures
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• v.19 no.2
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• pp.103-117
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• 2020

The effect of the foundation size on the efficiency of seismic base isolation using a layer of stone pebbles is experimentally investigated. Four scaled models of buildings with different stiffnesses (from very stiff to soft) were tested, each with the so-called small and large foundation, and exposed to four different accelerograms (different predominant periods and durations). Tests were conducted so that the strains in the model remained elastic and afterwards the models were tested until collapse. Each model was tested for the case of the foundation being supported on a rigid base and on an aseismic layer. Compared to the smaller foundation, the larger foundation results in a reduced rocking effect, higher earthquake forces and lower bearing capacity of the tested models, with respectable efficiency (reduced strain/stress, displacement and increase of the ultimate bearing capacity of the model) for the considered seismic base isolation compared to the foundation on a rigid base.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.129-134
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• 2002

The seismic performance evaluation and retrofit process are very important for old bridge. If the result is not appropriate, a retrofit process requires. Among the various retrofit methods, this paper selects a seismic isolator and evaluates a seismic performance of bridge. In case of applied seismic isolators to bridge, it proved that seismic capacity is increased by isolators A period of bridge is increased, and a seismic response is decreased. A method of evaluation is capacity spectrum method. By means of a graphical procedure, capacity spectrum estimates a performance level of structure by comparing the capacity of structure with the demand of earthquake ground motion on the structure. The objective of this study is to compare a seismic performance of a non-seismic designed bridge and seismic isolated bridge and to verify a effect of seismic isolator

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.712-722
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• 2020

Purpose: The damage from earthquakes with a magnitude of 5.0 or greater Korea has increased in South Korea. When a earthquake occurs, internal facilities and electric equipment besides urban structures will be damaged. Thus, in this paper, an earthquake-induced seismic isolation device with double slip fiction surfaces which can reduce the damage of electric power equipment such as distribution panel and then the seismic performance was evaluated. Method: To evaluate the seismic performance shaking table test was performed, a seismic performance comparison was performed according to the presence or absence of a seismic isolation device. The attenuation effect of the seismic isolation device are analyzed by comparing response acceleration and displacement for different frequencies and acceleration levels. Result: As a result of the test, the acceleration amplification was up to 42% less than when the seismic isolation device was installed in comparison to the other case without the seismic device. This is believed that the amplification energy has reduced because the displacement between the double slip friction surfaces of the seismic device play a role in dissipating the seismic energy. Conclusion: The seismic device with double slip friction surfaces has a greater earthquake attenuation effect in strong earthquakes than in weak ones, so the greater the frequency, the better the earthquake attenuation effect. Therefore, it is judged that earthquake energy can be decreased by applying to electric equipment such as distribution panels.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1231-1238
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• 2022

In this study, the reinforcement effect of the compression-only bridge seismic reinforcement method, which is mainly applied to old bridges, was studied through SSI analysis. As the analysis conditions, acceleration magnitudes of 0.1g, 0.15g, and 0.2 g were applied, and long-period and short-period seismic waves were applied. As a result of the analysis according to the assumed ground characteristics and structure size, the horizontal displacement at the reinforced section was reduced by about 9%, and the long-period seismic wave had a 95% larger displacement than the short-period seismic wave. In addition, an increase in acceleration of 0.1g resulted in a displacement of about 50%, and a large increase in displacement was observed in long-period seismic waves. As a result of the analysis, in the case of the compression-only bridge seismic reinforcement method, there was a reinforcing effect, so the field applicability was excellent.

• Structural Engineering and Mechanics
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• v.20 no.6
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• pp.655-672
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• 2005

Seismic random responses due to the wave passage effect are extensively investigated by using the pseudo excitation method (PEM). Two examples are used. The first is very simple but also very informative, while the second is a realistic suspension bridge. Numerical results show that the seismic responses vary significantly with wave speed, especially for low velocity or large span. Such variations are not monotonic, especially for flexible structures. The contributions of the dynamic and quasi-static components depend heavily on the seismic wave velocity and the natural frequencies of structures. For the lower natural frequency cases, the dynamic component has significant effects on the dynamic responses of the structure, whereas the quasi-static component dominates for higher natural frequencies unless the wave speed is also high. It is concluded that if insufficient data on local seismic wave velocity is available, it is advisable to select several possible velocity values in the seismic analysis and to choose the most conservative of the results thus obtained as the basis for design.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.5
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• pp.197-207
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• 2013

The seismic performance of school buildings has been a matter of common interest socially and academically. The structural system of the school buildings is representative of the domestic low-rise reinforced concrete moment resisting frames, which apply extensively infills in their masonry walls. The masonry infilled walls are divided into full masonry infill in the transverse direction and partial masonry infill in the longitudinal direction. The masonry infilled walls are usually not included in structural analysis during the design process, but affect significantly the seismic performance because they behave with surrounding frames simultaneously during earthquakes. Many researchers have studied the effect of the masonry infilled walls, but several issues have been missed such as the increase of asymmetry by adding the full masonry infill, the size of the mean strength of the full masonry infill, and short column effect by the partial masonry infill. The issues were analytically investigated and the results showed that they should be checked at least by nonlinear pushover analysis in the seismic performance evaluation process. The results also confirm the weakness of the guideline of Korean Educational Development Institute where the seismic performance is basically assessed without structural analysis.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.69-76
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• 2018

The paper presents preliminary investigation results for the effect of the baseline correction in the acceleration excitation method on finite element seismic analysis results (such as accumulated equivalent plastic strain, equivalent plastic strain considering cyclic plasticity, von Mises effective stress, etc) of nuclear safety Class I components. For investigation, finite element elastic-plastic time-history seismic analysis is performed for a surge line including a pressurizer lower head, a pressurizer surge nozzle, a surge piping, and a hot leg surge nozzle using the Chaboche hardening model. Analysis is performed for various seismic loading methods such as acceleration excitation methods with and without the baseline correction, and a displacement excitation method. Comparing finite element analysis results, the effect of the baseline correction is investigated. As a result of the investigation, it is identified that finite element analysis results using the three methods do not show significant difference.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.4
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• pp.169-177
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• 2021

In this paper, horizontal seismic responses of a structure built on a sunken mat foundation were compared with those built on a solid embedded mat foundation to investigate the effect of a sunken mat foundation on the horizontal response of a structure. Seismic analyses of a structure laid on the embedded mat foundation were performed by utilizing a pseudo-3D finite element software of P3DASS. Three bedrock earthquake records downloaded from the Pacific Earthquake Engineering Research Center database were scaled to reproduce weak-moderate earthquakes. Weak, medium, and stiff soil layers were considered for the seismic analyses of the structure-foundation-soil system. Parametric studies were performed for foundation radius, foundation embedment depth, and shear wave velocity of a soil layer to investigate their effect on the seismic response spectrum. The study result showed that the design spectrum of a structure built on a sunken mat foundation was similar to that with a solid embedded mat foundation showing a slight difference due to almost the same seismic base motion beneath both embedded foundations.