• Smart Structures and Systems
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• v.15 no.5
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• pp.1215-1232
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• 2015

In the present paper, a method for identifying damage in a multi storeyed shear building structure is presented using minimum number of modal parameters of the structure. A damage at any level of the structure may lead to a major failure if the damage is not attended at appropriate time. Hence an early detection of damage is essential. The proposed identification methodology requires experimentally determined sparse modal data of any particular mode as input to detect the location and extent of damage in the structure. Here, the first natural frequency and corresponding partial mode shape values are used as input to the model and results are compared by changing the sensor placement locations at different floors to conclude the best location of sensors for accurate damage identification. Initially experimental data are simulated numerically by solving eigen value problem of the damaged structure with inclusion of random noise on the vibration characteristics. Reliability of the procedure has been demonstrated through a few examples of multi storeyed shear structure with different damage scenarios and various noise levels. Validation of the methodology has also been done using dynamic data obtained through experiment conducted on a laboratory scale steel structure.

• Tunnel and Underground Space
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• v.6 no.2
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• pp.157-165
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• 1996

In order to analyze the effects of ground vibration caused by underground blasting having an effect on structure, the particle velocity and acceleration are calculated by using DYNPAK program. The DYNPAK program analyzes nonlinear transient dynamic problem and adopts the very popular and easily implemented, explicit, central difference scheme. In this program, the material behavior is assumed to be elasto-viscoplastic. Using the particle acceleration history, modal analysis method is applied to the forced vibration response of multiple-degree-of-freedom(MDOF) systems using unclupled equations of motion expressed in terms of the system's natural circular frequencies and modal damping factors. AS a means of evaluating the vibration behavior of building structure subjected to underground blasting, the time response of the displacements relative to the ground of five-story building is determined. It is concluded that the amount of explosives consumed per round, the location of structure, the properties of rock medium, the stiffness fo structure, etc. act on the important factors influencing on the safety of building and that the response of a structure subjected to a forced excitation can usually be obtained with reasonable accuracy by the modal analysis of only a few mode of the lower frequencies of the system.

• International Journal of High-Rise Buildings
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• v.1 no.3
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• pp.229-235
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• 2012

In this paper the progressive collapse potential of building structures designed for real construction projects were evaluated based on arbitrary column removal scenario using various alternate path methods specified in the GSA guidelines. The analysis model structures are a 22-story reinforced concrete moment frames with core wall building and a 44-story interior concrete core and exterior steel diagrid structure. The progressive collapse resisting capacities of the model structures were evaluated using the linear static, nonlinear static, and nonlinear dynamic analyses. The linear static analysis results showed that progressive collapse occurred in the 22-story model structure when an interior column was removed. However the structure turned out to be safe according to the nonlinear static and dynamic analyses. Similar results were observed in the 44-story diagrid structure. Based on the analysis results, it was concluded that, compared with nonlinear analysis procedures, the linear static method is conservative in the prediction of progressive collapse resisting capacity of building structure based on arbitrary column removal scenario.

• Computers and Concrete
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• v.9 no.4
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• pp.245-255
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• 2012

The damping effect of a Concrete-filled Rectangular Steel Tube (CRST) frame structure is studied in this paper. Viscous dampers are employed to insure the function of the building especially subjected to earthquakes, for some of the main vertical elements of the building are not continuous. The shaking table test of a 1:15 scale model was conducted under different earthquake excitations to recognize the seismic behavior of this building. And the vibration damping effect was also investigated by the shaking table test and the simulation analysis. The nonlinear time-history analysis of the shaking table test model was carried out by the finite element analysis program CANNY. The simulation model was constructed in accordance with the tested one and was analyzed under the same loading condition and the simulation effect was then validated by the tested results. Further more, the simulation analysis of the prototype structure was carried out by the same procedure. Both the simulated and tested results indicate that there are no obvious weak stories on the damping equipped structure, and the dampers can provide the probability of an irregular CRST frame structure to meet the requirements of the design code on energy dissipation and deformation limitation.

• Structural Engineering and Mechanics
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• v.71 no.2
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• pp.131-138
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• 2019

It is necessary to predict subway induced vibration if a new subway is to be built. To obtain the vibration response reliably, a three-dimensional (3D) FEM model, consisting of the tunnel, the soil, the subway load and the building above, is established in MIDAS GTS NX. For this study, it is a six-story frame structure built above line 3 of Guangzhou metro. The entire modeling process is described in detail, including the simplification of the carriage load and the determination of model parameters. Vibration measurements have been performed on the site of the building and the model is verified with the collected data. The predicted and measured vibration response are used together to assess vibration level due to the subway traffic in the building. The No.1 building can meet work and residence comfort requirement. This study demonstrates the applicability of the numerical train-tunnel-soil-structure model for the serviceability assessment of subway induced vibration and aims to provide practical references for engineering applications.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.9-12
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• 2010

Conventional apartment building projects have favored wall slab structure for the ease of construction and economic viability. However, wall slab structure, consisting of bearing walls, makes remodeling a difficult challenge. In addition, as the amendment to the Building Act in November, 2005 incentivized easy-to-remodel Rahmen structure design for apartment building in terms of floor area ratio and the number of stories, were are seeing more use of PC construct method in apartment building projects gradually. However, PC construction method requires complex connections between beams and columns, making it difficult to install and remove formwork. Furthermore, it is not possible to reuse forms after removal, generating lots of construction wastes, and it is necessary to install new forms again when the size of connection changes in line with modification of column cross-section. Researchers in Korea and elsewhere in the world have focused on structural performance of connection in PC construction method, with little attention to alternative approaches to improving connection forms for PC construction method. Accordingly, this research aims to study an approach to improving connection forms for PC construction method.

• Journal of architectural history
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• v.28 no.6
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• pp.7-18
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• 2019

This study is to find out the design concept of asymmetrical building with 4 purlins mainly in Sungkyunkwan(Confucian Shrines), Changgyeonggung palace and Changdeokgung palace The results are as follows: First, asymmetrical building with 4 purlins has the same height pillars, which was useful to control the side lenght and put a higher pillar without limit. Second, the side length of the asymmetrical building with 4 purlins is between 12 to 14 Ja[尺]. It's relatively longer than the minimum length(12 Ja) of 5 purlins architecture seen in later Joseon dynasty. Third, asymmetrical building with 4 purlins was not an anomalous structure when compared to 3 purlins and 5 purlins. It was actually a traditional style, unlike the current architectural recognition nowadays, which mainly focused on the balanced roof structure. These examples show that the architectures in Early Joseon dynasty were planned and constructed first according to the plane division that fit in a specific use or space.

• Structural Engineering and Mechanics
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• v.14 no.1
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• pp.21-38
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• 2002

A control algorithm combining viscous and non-linear Reid damping mechanisms has been recently proposed by the authors to command active friction dampers. In this paper, friction dampers and the proposed algorithm are applied to control the seismic responses of a nonlinear 20-story building. Piezoelectric stack actuators are used to implement the control algorithm. The capacity of each damper is determined by the practical size of piezoelectric actuators and the availability of power supply. The saturation effect of the actuators on the building responses is investigated. To minimize the peak story drift ratio or floor acceleration of the building structure, a practical sequential procedure is developed to sub-optimally place the dampers on various floors. The effectiveness of active friction dampers and the efficiency of the proposed sequential procedure are verified by subjecting the building structure to four earthquakes of various intensities. The performance of 80 dampers and 137 dampers installed on the structure is evaluated according to 5 criteria. Numerical simulations indicated that the proposed control algorithm effectively reduces the seismic responses of the uncontrolled 20-story building, such as inelastic deformation. The sub-optimal placement of dampers based on peak acceleration outperforms that based on peak drift ratio for structures subjected to near-fault ground motions. Saturation of piezoelectric actuators has adverse effect on floor acceleration.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.73-74
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• 2017

Below-grade concrete structure in residential buildings are exposed to various cracking conditions in between installation, construction and usage. Leakage follows the cracks along the exterior wall and floor slabs, and leakage occurring in this conditioning brings about discomfort to the users inside the building. This study analyzes a survey on the causes of leakage in below-grade concrete structure and proposes a solution method.

• Journal of the Korean Professional Engineers Association
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• v.28 no.2
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• pp.13-20
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• 1995

This paper Is to help the structural engineers for a better understanding of "Earthquake" with regard to the nature o( earthquake and the effect of earthquake on building structures. This reveals that the damage Inflicted upon by earthquake varies with many factors such as : magnitude of earthquake, distance from epicenter, site conditions, building structural characteristics and etc.. It is emphasized that in order to resist very strong earthquake, the ductility demand in the building structure Is important, and the proper duc-tility enables the structure to demonstrate inelastic rotation capacity of the joints and thus the structure may absorb and dissipate the seismic energy. This also presents a comparison between the current Americal UBC Code and the Korean Code, and the author expresses some points of concern on each code. Since earthquake almost invariably strikes at times and places, it is suggested that the current Korean Build-ing Code should be revised to enforce more stringent regulation against possible strong earthquake in the Korean peninsula.