• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.596-601
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• 1998

Rubber has been widely used as a good device for reducing the vibration in various fields including the anti seismic device like LRB. The damping characteristic is needed to be mathematically modeled to predict the dynamic behavior of the isolated system. In this paper, The frequency response function was obtained experimentally by the resonant method and simulation was performed with the hysteretic model using the resonant test result. the hysteretic behavior of the rubber can be explained by the change of the static stiffness obtained in the DC by the concept of the transfer function.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.2
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• pp.279-299
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• 2019

Recently occurred earthquake Gyeongju and Pohang served as a momentum to remind that Korean peninsular is not a safety zone from earthquake anymore. The importance of seismic design, therefore, have been realized and researches regarding design response spectrum have been actively carried out by many researchers and engineers. Current tunnel seismic design method is conducted to check safety of tunnel structure by dynamic numerical analysis with condition of completed lining installation, so, it is impossible to consider safety of tunnel behavior under construction. In this study, therefore, dynamic numerical analysis considering seismic wave propagations has been performed after back analysis using results from field monitoring of tunnel under construction in fractured zone and 1st reinforcement (shotcrete, rockbolt) behaviour are analyzed. Waves are classified by period characteristic (short and long). As a result, the difference depending on period characteristic is minor, and increasements of displacement are obtained at crown displacement due to seismic wave is 28~31%, 14~16% at left side of tunnel in the fractured zone, 13~27% at right side of tunnel in the bed rock, respectively. In case of shotcrete axial force is increased 113~115% at tunnel crown, 102% at left side, 106~110% at right side, respectively. Displacement and axial force of rockbolts which are selected by type of anchored grounds (only fractured zone, fractured zone and bed rock, only bedrock) are analyzed, as a result, rockbolt which is anchored to fractured zone and bed rock at the same time are weaker than any other case.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.91-99
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• 2010

In this study, the advanced numerical algorithm is developed which can performed the static and dynamic stochastic finite element analysis by considering the effect of uncertainties included in the member stiffness of steel cable-stayed bridges and seismic load. After conducting the linear and nonlinear initial shape analysis, the advanced numerical algorithm is the assessment tool which can performed structural the response analysis considering the static linearity and non-linearity of before or after induced intial tensile force, and examined the reliability assessment more efficiently. The verification of the developed numerical algorithm is evaluated by analyzing the regression analysis and coefficient of correlation using the direct monte carlo simulation. Also, the dynamic response characteristic and coefficient of variation of the steel cable-stayed bridge is calculated by considering the uncertainty of random variables using the developed numerical algorithm. In addition, the quantitative structural safety of the steel cable-stayed bridges is evaluated by conducting the reliability assessment based upon the dynamic stochastic finite element analysis result.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.73-82
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• 2015

In evaluating lateral behavior on the seismic and wind load, the purpose of sensitivity analysis is to find critical variables and to identify characteristic response with variability of variables. The sensitivity analysis is very important in structural diagnosis, repair and reinforcement field. This study investigates the sensitivity by linear static analysis applying the TDA method in changing angles of diagrid braces on the same height structures. In case of mid rise model, under the seismic load, the brace member is determined as a major variable at $58^{\circ}$ but a high rise model, under the wind load, has the brace member as a major variable at $67.4^{\circ}$. In addition, location of critical sensitivity on the mid rise model is distributed over middle section, while it is distributed lower section on the high rise model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.39-47
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• 1990

The generation of artificial accelerograms considering the characteristic of earthquakes in the Korean peninsula for a time history analysis of structures is accomplised by the stochastic method. The engineering data such as a representative shape of envelope function and an effective duration are investigated from the instrumental records. The maximum ground acceleration value is based on seismic zoning map which are constructed for the Korean peninsula. The acceleration-time histories are generated for two different types of earthquake motions and two types of soil conditions. In the study, the maximum ground acceleration value of 0.2 g and effective durations of 24 seconds are used. The validity of the artificial accelerograms is obtained by the comparison with the required envelope functions and the design response spectrum.

• International Journal of High-Rise Buildings
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• v.1 no.1
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• pp.37-51
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• 2012

New generation of tall and complex buildings systems are now introduced that are reflective of the latest development in materials, design, sustainability, construction, and IT technologies. While the complexity in design is being overcome by the availability and advances in structural analysis tools and readily advanced software, the design of these buildings are still reliant on minimum code requirements that yet to be validated in full scale. The involvement of the author in the design and construction planning of Burj Khalifa since its inception until its completion prompted the author to conceptually develop an extensive survey and real-time structural health monitoring program to validate all the fundamental assumptions mad for the design and construction planning of the tower. The Burj Khalifa Project is the tallest structure ever built by man; the tower is 828 meters tall and comprises of 162 floors above grade and 3 basement levels. Early integration of aerodynamic shaping and wind engineering played a major role in the architectural massing and design of this multi-use tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria established at the onset of the project design. Understanding the structural and foundation system behaviors of the tower are the key fundamental drivers for the development and execution of a state-of-the-art survey and structural health monitoring (SHM) programs. Therefore, the focus of this paper is to discuss the execution of the survey and real-time structural health monitoring programs to confirm the structural behavioral response of the tower during construction stage and during its service life; the monitoring programs included 1) monitoring the tower's foundation system, 2) monitoring the foundation settlement, 3) measuring the strains of the tower vertical elements, 4) measuring the wall and column vertical shortening due to elastic, shrinkage and creep effects, 5) measuring the lateral displacement of the tower under its own gravity loads (including asymmetrical effects) resulting from immediate elastic and long term creep effects, 6) measuring the building lateral movements and dynamic characteristic in real time during construction, 7) measuring the building displacements, accelerations, dynamic characteristics, and structural behavior in real time under building permanent conditions, 8) and monitoring the Pinnacle dynamic behavior and fatigue characteristics. This extensive SHM program has resulted in extensive insight into the structural response of the tower, allowed control the construction process, allowed for the evaluation of the structural response in effective and immediate manner and it allowed for immediate correlation between the measured and the predicted behavior. The survey and SHM programs developed for Burj Khalifa will with no doubt pioneer the use of new survey techniques and the execution of new SHM program concepts as part of the fundamental design of building structures. Moreover, this survey and SHM programs will be benchmarked as a model for the development of future generation of SHM programs for all critical and essential facilities, however, but with much improved devices and technologies, which are now being considered by the author for another tall and complex building development, that is presently under construction.

• Journal of the Korean GEO-environmental Society
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• v.18 no.5
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• pp.55-60
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• 2017

It is critical for Korea to make effective use of limited space as it has dense population and high traffic volume compared to its terrestrial area. To resolve this issue, diverse types of underground structures have increasingly been applied so far, and one of the most representative structures is double-deck tunnel. It has upper and lower roads separated by middle slab that shows dynamic behavior according to the vehicle and earthquake loads. In case of the characteristics of earthquake response, it is necessary to have exploratory study as it has high loads, complex working mechanism, and difficult theoretical approach. In order to understand the characteristics of earthquake response based on the supporting conditions of middle slab in double-deck tunnel, this study conducts indoor shaking table test with 3 test cases: (1) fix both brackets, (2) free and fix at each bracket and (3) free at both brackets for 2 seismic waves of artificial and Gyeongju earthquake. The result shows if the middle slab is free at both brackets, the acceleration response is reduced 41% for artificial earthquake and 60% for Gyeongju earthquake compared to the one with fix at both brackets.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.1
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• pp.29-42
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• 2005

Considering the effect by uncertainty in the structures, it is reasonable that the safety examination has to be performed by using method of reliability evaluation. Therefore, in this study, program is developed which can perform the reliability analysis or the dynamic response analysis more efficiently by formularizing the stochastic finite element analysis suitable for the existing reliability analysis about the cable stayed bridge suffering the seismic loads. Based on this program, the characteristic of dynamic responses is analyzed quantitatively by examining the average, the standard deviation and the coefficient of variance about the displacement, the resistance and the tension of cable according to the random variables. and the safety of cable stayed bridge is evaluated by examining of reliability index and failure probability

• Computational Structural Engineering
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• v.7 no.3
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• pp.95-103
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• 1994

The safety related components in the nuclear power plant should be designed to withstand the seismic load. Among these components the integrity of reactor internals under earthquake load is important in stand points of safety and economics, because these are classified to Seismic Class I components. So far the modelling methods of reactor internals have been investigated by many authors. In this paper, the dynamic behaviour of reactor internals of Yong Gwang 1&2 nuclear power plants under SSE(Safe Shutdown Earthquake) load is analyzed by using of the simpled Global Beam Model. For this, as a first step, the characteristic analysis of reactor internal components are performed by using of the finite element code ANSYS. And the Global Beam Model for reactor internals which includes beam elements, nonlinear impact springs which have gaps in upper and lower positions, and hydrodynamical couplings which simulate the fluid-filled cylinders of reactor vessel and core barrel structures is established. And for the exciting external force the response spectrum which is applied to reactor support is converted to the time history input. With this excitation and the model the dynamic behaviour of reactor internals is obtained. As the results, the structural integrity of reactor internal components under seismic excitation is verified and the input for the detailed duel assembly series model could be obtained. And the simplicity and effectiveness of Global Beam Model and the economics of the explicit Runge-Kutta-Gills algorithm in impact problem of high frequency interface components are confirmed.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.361-373
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• 2014

As the height and beam span of buildings built in the construction market increase, increasingly higher quality is being required of the construction materials. In response to this trend, 800MPa tensile strength class steel was developed in domestic company. Currently, experiments applying flexural member, compression member, and connections are continuously conducted, but a design guideline for high strength steel has yet to be established. Among those construction materials, for the high strength steel beam-to-column connections, the evaluation of implementing ductile connections for the high strength steel beam-to-column connections is producing pessimistic results and the number of related researches is inadequate because of the high yield ratio, which is the characteristic of high strength steel. This study on implementation of ductile connections made of high strength steel was conducted using the connection detail as the variable, for the purpose of enhancing the deformation capacity of high strength steel beam-to-column connections. Cyclic loading test and nonlinear finite element analysis were conducted with full-scale mock-up connection models with the applied connection details. As a result, the structural performance of high-strength steel beam-to-column connection with presented detail was contented with demand of Special Moment Frames of KBC standard.