• Geomechanics and Engineering
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• 제9권2호
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• pp.145-167
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• 2015

Digital simulation has recently become the preferred method for designing complex and dynamic systems. Simulation packages provide interactive, block-diagram environment for modeling and simulating dynamic models. The block diagrams in simulation models are flowcharts which describe the components of dynamic systems and their interaction. This paper is the first part of the study for determining the seismic behavior of soil systems. The aim of this part is to present the constructed block diagrams for discrete-time analysis of seismic site amplification in layered media for vertically propagating shear waves. Detailed block diagrams are constructed for single and multiple soil layers by considering wave propagation with and without damping, respectively. The block diagrams for recursive filter to model attenuation in discrete-time form are also constructed. Finite difference method is used for strain calculation. The block diagrams are developed by utilizing Simulink which is a software add-on to Matlab.

• 한국지진공학회논문집
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• 제23권1호
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• pp.19-29
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• 2019

Recent earthquakes in Korea caused some damages to stone pagodas and thereby awakened the importance of earthquake preparedness. Korean stone pagodas which have been built with very creative style of material use and construction method are worthy of world heritage. Each stone pagoda consists of three parts: top; body; and base. However each tower is uniquely defined by its own features, which makes it more difficult to generalize the seismic assessment method for stone pagodas. This study has focused on qualitative preliminary evaluation of stone pagodas that enables us to compare the relative seismic performance across major aspects among many various Korean pagodas. Specifically an analytical model for multi-block stone pagodas is to be proposed upon the investigation of structural characteristics of stone pagoda and their dynamic behavior. A strategy for seismic evaluation of heritage stone pagodas is to be established and major evaluation factors appropriate for the qualitative evaluation are identified. The evaluation factors for overall seismic resisting behavior of stone pagodas are selected based on the dynamic motions of a rigid block and its limit state. Numerical simulation analysis using discrete element method is performed to analyze the sensitivity of each factor to earthquake and discuss some effects on seismic performance.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.275-283
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• 2002

In this study, the shaking table tests of block systems on the rigid base have been performed to identify the seismic response and the dynamic behavior of the piled multi-block systems. To understand the characteristics of seismic response of piled multi-block systems, it is necessary to understand the dynamic behavior of single block system. Therefore, the skating table test of the single block system has been performed first. Moreover, by performing the shaking table tests of multi-block systems, the characteristics of dynamic behavior of piled multi-block systems have been analyzed. Also in this study, the distinct element method(DEM) has been used to analyze the nonlinear behavior of the piled multi-block systems. The results of the shaking table tests show that the response of the multi-block systems is very complicated. But by using DEM, the behavior of piled multi-block systems has been predicted and described well.

• 한국지진공학회논문집
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• 제22권6호
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• pp.333-343
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• 2018

In this paper, we study the existing results of the structure-soil-structure interaction (SSSI) effect on seismic responses of structures and summarize important parameters. The parameters considered in this study are a combination of buildings in the power block of a nuclear power plant, the characteristics of earthquake ground motions and its direction, and the characteristics embedded under the ground. Based on these parameters, the seismic analysis model of the structures in the power block of the nuclear power plant is developed and the structure-soil-structure interaction analyses are performed to analyze the influence of the parameters on the seismic response. For all analyses, the soil-structure interaction (SSI) analysis program CNU-KIESSI, which was developed to enable large-sized seismic analysis, is used. In addition, the SSI analyses is performed on individual structures and the results are compared with the SSSI analysis results. Finally, the influence of the parameters on the seismic response of the structure due to the SSSI effect is reviewed through comparison of the analysis results.

• Earthquakes and Structures
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• 제24권3호
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• pp.205-215
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• 2023

Currently, many studies are underway at home and abroad on the seismic performance evaluation and dry construction method of the masonry structure. In this study, a dry stack masonry wall system without mortar using concrete blocks is proposed, and investigate the seismic performance of dry filling wall frames through experimental studies. First, two types of standard blocks and key blocks were designed to assemble dry walls of concrete blocks. And then, three types of experiments were manufactured, including pure frame, 1/2 height filling wall frame, and full height filling wall frame, and cyclic load experiments in horizontal direction were performed to analyze crack patterns, load displacement history, rebar deformation yield, effective stiffness change, displacement ductility, and energy dissipation capacity. According to the experimental results, the full height filling wall frame had the largest horizontal resistance against the earthquake load and showed a high energy dissipation capacity. However, the 1/2 height filling wall frame requires attention because the filling wall constrains the effective span of the column, limiting the horizontal displacement of the frame. In addition, the concrete block was firmly assembled in the vertical direction of the wall as the horizontal movement between the concrete blocks was allowed within installation margin, and there was no dropping of the assembled concrete block.

• 대한기계학회논문집A
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• 제33권11호
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• pp.1288-1293
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• 2009

This paper discusses about modeling method to simulate a nonlinear behavior like sliding or rocking of two stacked body system under earthquake condition. A double body system design can be an option to reduce seismic response of a component in comparison to a single body system for free standing structures. Therefore, according to the priority of components, the structure is to be designed by proper ratio of partition in their height for improvement of seismic capability and structural integrity. Nonlinear modeling and analysis using simple rigid body and dynamic system has been performed to check the trend in such cases. As a result, one of the two bodies can be chosen to reduce the seismic response from energy absorption of the other one by appropriate application of friction ratios not only in slip-slip condition but in slip-rock condition.

• Earthquakes and Structures
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• 제6권1호
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• pp.71-87
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• 2014

Interaction between closely-spaced buildings subject to earthquake induced strong ground motions, termed in the literature as "seismic pounding", occurs commonly during major seismic events in contemporary congested urban environments. Seismic pounding is not taken into account by current codes of practice and is rarely considered in practice at the design stage of new buildings constructed "in contact" with existing ones. Thus far, limited research work has been devoted to quantify the influence of slab-to-slab pounding on the inelastic seismic demands at critical locations of structural members in adjacent structures that are not aligned in series. In this respect, this paper considers a typical case study of a "new" reinforced concrete (R/C) EC8-compliant, torsionally sensitive, 7-story corner building constructed within a block, in bi-lateral contact with two existing R/C 5-story structures with same height floors. A non-linear local plasticity numerical model is developed and a series of non-linear time-history analyses is undertaken considering the corner building "in isolation" from the existing ones (no-pounding case), and in combination with the existing ones (pounding case). Numerical results are reported in terms of averages of ratios of peak inelastic rotation demands at all structural elements (beams, columns, shear walls) at each storey. It is shown that seismic pounding reduces on average the inelastic demands of the structural members at the lower floors of the 7-story building. However, the discrepancy in structural response of the entire block due to torsion-induced, bi-directionally seismic pounding is substantial as a result of the complex nonlinear dynamics of the coupled building block system.

• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.21-33
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• 2015

This study aimed to present a reinforced concrete block system that reduces the flange thickness of the existing form block used in new buildings and optimizes the web form, and can thus capable of being used in the seismic retrofit of new and existing buildings. By conducting a compression test and finite element analysis based on the block and grouted concrete strength, it attempted to determine the compression capacity of the form block that can be used in new construction and seismic retrofit. As a result, the comparison of the strength equation from Architectural Institute of Japan to the prism compression test showed that the mortar coefficient of 0.55 was suitable instead of 0.75 recommended in the equation. The stress-strain relation of the block was proposed as a bi-linear model based on the compression test result of the single form block. Using the proposed model, finite element analysis was conducted on the prism specimens, and it was shown that the proposed model predicted the compression behavior of the form block appropriately.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.448-454
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• 2000

Piled multi-block system has been frequently adopted in the historic structures or monuments of cultural heritage. It is well known that such a structural system is very vulnerable to the earthquake shaking. If the structure is of slender type, then it may experience overturning at very low level intensity of ground shaking. One of the methods used to protect such structures from earthquake is seismic isolation system. But the behavior of multi-block systems mounted on the isolated basis is not well understood yet. In this paper we investigate the dynamic behavior of single slender rigid block mounted on the three different isolation systems, i.e., P-F system, FPS and LRB system. Sliding at the isolation interface of P-F system and FPS is formulated based on Coulomb friction. The mounted single block is assumed undergoing rocking or sticking only. Impacting of a single block is described using distinct element method (DEM). Free vibrations due to a prescribed initial conditions are studied. Responses to the harmonic excitation and earthquake motions are calculated

• 한국지반공학회논문집
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• 제38권5호
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• pp.19-33
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• 2022

지진시 성토사면의 잔류변위 예측에 가장 많이 사용되는 방법은 Newmark변위법이다. Newmark변위법은 지진시 강체원호의 관성력에 의한 미끌어짐량을 산정하는 방법으로 한계상태평형이론에 근거하여 산정된다. 따라서, 원호의 미끌어짐이 발생하지 않는 항복가속도 이하의 지진이 발생하는 경우 잔류변위가 발생하지 않는다고 가정한다. Newmark 변위법은 최초 제안 이후 지진응답해석기법의 결과를 도입하는 방향으로 개선되었다. 본 논문에서는 방조제 예제 단면에 대해서 Newmark변위법의 적용방법과 비선형응답이력 해석을 통한 내진성능평가 결과의 차이를 살펴보았다. 검토 결과, 설계안전율이 큰 방조제 제체에서는 Newmark변위법에 의한 잔류변위는 거의 발생하지 않았다. 반면, 비선형 응답이력해석의 결과는 비교적 유의미한 잔류변위를 나타냄을 알 수 있었다.