In recent years, the number of earthquakes has increased worldwide. There has been an extreme increase on the Korea Peninsula, which is considered a safety zone for earthquakes. In particular, in the event of earthquakes, most structures on the Korea Peninsula are severely damaged, because most are not designed to withstand them. Damage to and destruction of civil structures, such as bridges, nuclear facilities, and dams, is worse than that of other structures. It is necessary to evaluate and predict the extent of damage by earthquake magnitude, as the magnitude of earthquakes is increasing as well as the frequency. A major feature of the occurrence of earthquakes is uncertainty. For this reason, it is necessary to adopt a stochastic approach, and studies using this approach are increasing. However, although there have been several studies on bridges and nuclear facilities, there have been few studies on probabilistic seismic risk evaluation for multi-functional weirs. Thus, this study presents 3D multi-functional weirs and performs a time history analysis by using LS-DYNA, a general structure analysis program. Probabilistic seismic fragility assessment is conducted by Monte Carlo simulation.

In Korea, the occurrence frequency of earthquakes has recently increased, compared with the past. So, the various damages for cultural properties due to earthquake can be expected, and especially fortress structure is vulnerable to earthquake. Therefore, the resonable seismic characteristics evaluation is required to secure the safety for fortress structure with the various construction and configuration types. Also, we should consider the various applied load conditions as design variables. To this end, this study classifies fortress structures according to the construction and configuration types, and then applies the discrete element method to model and analyze fortress structures. Finally, the seismic characteristics is evaluated through slip condition due to the analysis results considering the various design variables.

3D프린팅 공법은 설계 데이터 및 제품의 특성에 따라 액체 또는 분말가루 형태의 폴리머, 금속 등의 재료를 사용한다. 3D프린팅 공법의 제조방식은 적층방식으로 입체구조물을 층층이 쌓아올려 3차원형상을 제조하는 방식을 말한다. 3D프린팅 기술은 30년(1980년대) 전에 개발된 기술이지만 최근 몇 년 사이에 업계의 관심이 집중되고 있다. 3D프린팅 기술의 적용범위는 기계 산업분야에서 의료분야, 항공 분야, 건설 및 토목분야 등으로 그 범위가 점점 확대되어가 고 있다 컨투어크래프팅(Contour Crafting)은 미국 남가주대학에서 15년(2000) 전에 세라믹재료를 이용하여 개발된 3D프린팅 공법이다. Trowel 구조를 도입하여 3D프린팅 공법의 핵심적 단점인 외부표면을 매끄럽게 하면서 3D자유형상을 제작하는 것이다. 현재의 이 공법은 시멘트를 이용 하여 구조물의 부가구성물뿐만이 아니라 전체구조물을 자동으로 만드는 것을 목적으로 한다. 또한 각층의 두께 및 폭이 일반 3D프린팅 공법과 비교할 수 없이 크고 넓게 함으로 건설 및 토목분야의 적용이 가능하다. 특히, 콘크리트재료를 이용하여 토목용 2차구조물 제작에 대한 기초적인 조사 및 개념을 상세히 설명된다

Recently, the damage caused by typhoons and strong winds, which frequently occur as a result of global climate change, is on the rise. Soundproofing and windshield walls installed on roads often fail to function because of damage due to strong winds. Therefore, in this study, strong wind fragility evaluation was performed to predict the probability of failure of soundproof / windproof walls from wind loads. A three-node bending experiment was carried out to investigate the material characteristics of the aluminum frame which was installed on the actual soundproof wall. Based on the results of this experiment, the resistance performance of target structure was calculated, and the frame damage was selected as the performance limit state. Wind loads acting on 4m x 1m individual element soundproof wall was compared with the resistance capacity by Monte Carlo simulation method. In the future, the evaluation of the strong wind safety of the sound barrier structure should be proceeded by setting the limit state and performing the vulnerability evaluation through the additional experimental data. This work can become guideline information for future design of soundproof and windproof wall.

Numerical behavior of FRP(Fiber Reinforced Polymer) panel in steel frame structure was evaluated through the finite element analysis in this study. In order to numerical analysis, a experimental test results was used to develop a three dimensional finite element model of steel frame specimen. Numerical results of the steel frame specimen was well predicted the experimental behavior of steel frame specimen. Based on the developed three dimensional finite element model of steel frame specimen, the behavior of FRP panel in the steel frame specimen was evaluated. From the numerical analysis results, strength of the steel frame specimen with FRP panel was governed by FRP panel. Also, diagonal compression behavior governed the FRP panel in the steel frame specimen in the numerical analysis results.

As an alternative to conventional explosive methods for demolition of concrete structures and rocks, the use of non-explosive demolition agents can be considered to reduce noise, vibration, and dust emissions during the demolition process. In this study, we conduct finite element analysis for crack initiation and propagation caused by the expansion of non-explosive demolition agents in square concrete structures. The predicted crack patterns are compared with the experimental results in the literature. The minimum values of the required expansion pressure of non-explosive demolition agents are also estimated, which depend upon the arrangement of non-explosive demolition agents and empty holes. Furthermore, we investigate the effect of empty holes on the fragmentation of concrete structures, and discuss the effective arrangement of non-explosive demolition agents and empty holes for fragmentation improvement.

Wind tower structure has relatively simple shape compared to other structures, but due to its characteristics, various and irregular environmental loads are applied. These loads cause vibrations at tower, and can cause failure of the structure if over vibration occurs. Vibration occurred at structures is gradually exhausted by damping of the structures, and if high damping is ensured, the failure of the structure due to over vibration can be prevented. In this study, the vibration reduction effects are to be analyzed through FEM analysis by examining the top displacement, bottom moment, and bottom fatigue damage of the structure depending on damping ratio of the wind tower structure.

This study investigates dynamic characteristics of a 2MW wind turbine structure by long-term response monitoring with accelerometers, tiltmeter and strain gauges. The object wind turbine structure is located in Jeju Island, Korea. The natural frequency and damping ratio were evaluated by least-square frequency domain decomposition and random decrement technique using acceleration response data. As a result, it was found that natural frequencies with 1st, 2nd and 3rd modes, and blade passing frequencies with 1P, 2P and 3P were clearly showed from power spectral densities of acceleration reponses. Furthermore, 1st model frequencies were almost constant with increase in standard deviations of acceleration responses. Another notable observation was that when standard deviations of acceleration responses were small, damping ratios showed to diverge. However, when standard deviations of acceleration responses had large values, damping ratios were converged to about 0.5%.

Floating PV generation system, renewable energy power plant, is able to overcome the disadvantages of ground PV generation system and improve generating efficiency. The frame structural system is an established technology among a diversity of structural technologies which has been developed for related fields. In this paper, the both structural safety and characteristics of floating PV generation structures depend on the different placement angle of solar module are investigated to improve the commercial viability, the structural safety, and characteristics of floating PV generation structures. In addition, for the estimation of structural safety, FE analyses are conducted. From the results, the lower placement angle of solar module improves the structural safety of floating PV generation system.

A behavior of FRP(Fiber Reinforced Polymer) panel in a steel frame structure was evaluated through the finite element analysis in this study. In order to numerical analysis, a experimental test results was used to develop a three dimensional finite element model of steel frame specimen. Numerical results of the steel frame specimen was well predicted the experimental behavior of steel frame specimen. Based on the developed three dimensional finite element model of steel frame specimen, the behavior of FRP panel in the steel frame specimen was evaluated. From the numerical analysis results, strength of the steel frame specimen with FRP panel was governed by FRP panel. Also, diagonal compression behavior governed the FRP panel in the steel frame specimen in the numerical analysis results.

In this paper, a study on noise reduction characteristics of the precast floating track system, being developed as measures to mitigate noise and vibration of existing as well as constructing elevated railroad stations, is presented using numerical analysis. One of the most prominent sound analysis program, Virtual Lab., is utilized in investigating noise reduction performance of the precast floating track system, and structural velocity data, obtained from vibration analysis on a model-updated elevated railroad station considering vehicle-track-structure interaction, are used for the input of the sound analysis. The sound analysis is performed using the finite element method, and noise reduction performance before and after installing the precast floating track system is compared at three enclosed areas in the Daecheon Station, selected as a representative of elevated railroad stations in this nation. From the comparison result, it is seen that the precast floating track system can decrease noise by average of 5dB∼8dB when the Saemaeul train passing through the station and 10dB∼15dB when the KTX train passing through. Also, the noise reduction characteristics is different depending on the type of train and the distance from the track.

When reinforcing an existing reinforced concrete beam-column building with a precast concrete panel, special connection between the PC member and the RC member is required to solve the time dependent deformation of the RC member and to receive the large shear forces. The aim of this study is to obtain the shear strength of upper connection between the existing RC beam-column and infilled PC wall panels in experimentally and theoretically. Thus, the static shear loading tests were conducted on the 6 specimens with the plate connection. Shear failure was resulted from the weakest portion of interior PC panel, exterior RC, and the connection, when the PC portion which located at the center of specimen was pulled upward from the bottom. T he experimental result was compared with analytical result from ACI 318M-14 Chapter 17 for the shear strength of post-installed anchor and PCI Handbook 7th edition 6.8 Structural Steel Corbel (PCI Design Handbook 7th edition, 2010) for the strength of cast-in H-beam. The analytical and experimental results show final failure at the same location. The failure loading of experiment showed larger than average 6% to that of the analysis.

In order to modeling seismic isolation system such as lead-rubber bearing (LRB), bilinear model is widely used by many researchers. In general, an actual force-displacement relationship for LRB has a smooth hysteretic shape. So, Bouc-Wen model with smooth hysteretic shape represents more accurately actual hysteretic shape than bilinear model. In this study, seismic responses for seismically isolated nuclear power plant (NPP) with LRB modelled by Bouc-Wen and bilinear models are compared with those of NPP without seismic isolation system. To evaluate effect of earthquake characteristics for seismic responses of NPP isolated by LRB, 5 different site class earthquakes distinguished by Geomatrix 3rd Letter Site Classification and artificially generated earthquakes corresponding to standard design spectrum by Reg. Guide 1.60 are used as input earthquakes. From the seismic response results of seismically isolated NPP, it can be observed that maximum displacements of seismic isolation modelled by Bouc-Wen model are larger than those by bilinear model. Seismic responses of NPP with LRB is significantly reduced than those without LRB. This reduction effect for seismic responses of NPP subjected to Site A (rock) earthquakes is larger than that to Site E (soft soil) earthquakes.

본 연구의 목적은 시스템 식별기술과 칼만필터링을 기반으로 계측된 가속도응답을 이용하여 구조물에 작용하는 모달하중을 역으로 추정하는 기법을 제시하는데 있다. 하중추정 과정에서 가속도응답은 모드응답으로 분해되며 각 모드응답에 대한 모달하중을 역으로 추정한다. 역해석과정에서 발생하는 ill-posed문제를 피하기 위하여 가상진동기에 의해 구조물의 고유진동수와 감쇠비를 보다 정밀하게 구하기 위한 시스템 식별법을 사용하였다. 본 연구에서 제안된 기법의 적용성을 위하여 40층의 철골구조물에 태풍이 작용 했을 때 계측된 가속도를 사용하였다. 적용결과에 의하면 본 연구에서 제안된 하중추정법에 의하여 모달하중 추정이 가능함을 알 수 있었다.

OBJECTIVES : Fixed roadside objects are a threat to drivers when their vehicles deviate from the road. Therefore, such roadside objects need to be suitably dealt with to decrease accidents. This study determines the factors affecting the severity of accidents because of fixed roadside objects. METHODS : This study analyzed the crash severity impact of fixed roadside objects by using ordered probit regression as the analysis methodology. In this research, data from 896 traffic accidents reported in the last three years were used. These accidents consisted of sole-car accidents, fixed roadside object accidents, and lane-departure accidents on the national highway of Korea. The accident severity was classified as light injury, severe injury, and death. The factors relating to the road and the driver were collected as independent variables. RESULTS: The result of the analysis showed that the variables of the crash severity impact are the collision location (left side), gender of the driver (female), alcohol use, collision facility (roadside trees, traffic signals, telephone poles), and type of road (rural segments). Additionally, the collision location (left side), gender of the driver (female), alcohol use, collision facility (street trees, traffic signals, telephone poles), and type of road (rural segments), in order of influence, were found to be the factors affecting the crash severity in accidents due to fixed roadside objects. CONCLUSIONS: An alternative solution is urgently required to reduce the crash severity in accidents due to fixed roadside objects. Such a solution can consider the appropriate places to install breakaway devices and energy-absorbing systems.