• International journal of steel structures
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• v.18 no.4
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• pp.1431-1439
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• 2018

For floating buildings may fl oat on the water for a long time, they are constantly affected by various environmental loads such as wind and wave loads. In this study to find the wave effect on the floating building, five models are designed using steel moment resisting frame. It is assumed that the lower part of the floating building is a reinforced concrete pontoon, while the upper part is a three-story steel frame. To analyze floating buildings affected by wind and wave loads, hydro-dynamic and substructure analysis are performed. As input loads, this study set limits that the mean wind velocity is 35 m/s and the significant wave height is 0.5 m for the residential building. From the hydrodynamic analysis, the time-history acceleration of building is obtained and transformed into a base ground input for a substructure analysis of the superstructure of the building. Finally the mean of the maximum from 30 dynamic analysis of the floating buildings are used to be compared with the results of the same model on the ground. It was shown that the dynamic results with wind and wave loads are not always lesser than the static results which are calculated with static equivalent wind load for a building that is located on the ground.

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.19 no.2
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• pp.28-31
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• 2015

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.315-321
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• 2012

The utility-interactive inverter with critical loads should supply continuous and stable voltage to critical loads even during the grid fault. The conventional control method which performs current control for grid-connected mode and voltage control for stand-alone mode undergoes the critical load voltage variation during grid fault. The critical load voltage may have large transient when the inverter performs mode transfer after the islanding detection. Recently, the indirect current control method which does not have the transient state during not only islanding detection but also the mode transfer has been proposed. However, since the voltage control is maintained even during the grid-connected mode it is difficult to detect the islanding. This paper proposes an active anti-islanding method suitable for the indirect current control method which does not have NDZ(Non-Detection Zone).

• Journal of the Society of Naval Architects of Korea
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• v.52 no.6
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• pp.509-519
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• 2015

Mooring stability of floating dock for construction of Ichthys CPF (central processing facilities), an ultra large offshore structure, was studied. Normal and typhoon conditions were considered for mooring analysis. There have been changes in construction stages of the CPF as project progresses. These changes were reflected on the mooring stability analysis for both conditions. In order to secure the mooring stability of the floating dock for Ichthys CPF under typhoon, maximum loads of mooring chains and maximum offset of the floating dock with Ichthys CPF were examined. Also the shapes of the catenary mooring were investigated to check interferences among mooring chains. As it was confirmed that the mooring loads were within SWL (safe working load) of mooring chains and underwater sinkers, the mooring stability of the floating dock for construction of Ichthys CPF was secured. By achieving security of mooring stability of the floating dock, it is assured that Ichthys project is on its way to success.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.665-674
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• 2002

The back-to-back and box-shaped headers used in light gauge steel structures have some disadvantages, i.e., construction efficiency and cost competitiveness. As such, cold-formed steel L-shaped headers have been developed and are used actively in advanced nations. However, this system has not been used in Korea because of inadequate investigation and adaptation efforts and lack of application example. Thus, this research evaluated the structural performance of L-header using buckling analyses and bending tests. Test results were compared using the AISI design criteria. Test results showed that local buckling and distortional buckling governed buckling behavior in gravity loads and uplift loads, respectively. These results were consistent with the calculated nomial strengths using the AISI design criteria.

• KIEAE Journal
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• v.10 no.1
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• pp.25-31
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• 2010

An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. The composite beams tested in this study were designed to reduce the depth of the slab and beam. The slabs are constructed on top of the edges of the Structural Composite Hybrid System, instead of on top of the steel flange, decreasing the depth of the beams. When concrete is cast on the metal deck plate located on the edges of the precast concrete, the weight of the concrete slabs and other construction loads must be supported by the contacts between the steel and the precast concrete. This interface must not exhibit bearing failures, shear failures, and failures caused by torque due to the loading of the precast concrete. When the contact area between the concrete and the bottom flange of the steel beam is small, these failures of the concrete are likely and must be prevented. The premature failure of precast concrete must not also be present when the weight of the concrete slabs and other construction loads is loaded. This paper presents a load carrying capacity of Structural Composite Hybrid System in order to observe the failure mode. The symmetrically distributed loading that caused the failure of the composite beam was found. The paper also provides design recommendations of such type of composite structure.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.227-238
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• 2024

Sparse regularization methods have proven effective in addressing the ill-posed equations encountered in moving force identification (MFI). However, the complexity of vehicle loads is often ignored in existing studies aiming at enhancing MFI accuracy. To tackle this issue, a double 𝑙₁ regularization method is proposed for MFI based on a response spectrum-based weighted dictionary in this study. Firstly, the relationship between vehicle-induced responses and moving vehicle loads (MVL) is established. The structural responses are then expanded in the frequency domain to obtain the prior knowledge related to MVL and to further construct a response spectrum-based weighted dictionary for MFI with a higher accuracy. Secondly, with the utilization of this weighted dictionary, a double 𝑙₁ regularization framework is presented for identifying the static and dynamic components of MVL by the alternating direction method of multipliers (ADMM) method successively. To assess the performance of the proposed method, two different types of MVL, such as composed of trigonometric functions and driven from a 1/4 bridge-vehicle model, are adopted to conduct numerical simulations. Furthermore, a series of MFI experimental verifications are carried out in laboratory. The results shows that the proposed method's higher accuracy and strong robustness to noises compared with other traditional regularization methods.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.297-302
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• 2011

Railway construction in the random vibration natural phenomena, as well as a relatively regular train loads for dynamic loads, such as a usability and safety should be ensured. Vibration due to train loads and seismic vibrations caused by wind compared to the typically very small in size, rather than the safety of the structure affects the usability. Recently in the downtown area, ground and underground facilities, such as a permanent facility that may cause excessive vibration increases, associated with the construction of these transportation facilities on ground vibrations of structures has been increasing concern and complaint. More recently, high-speed train vibration and noise due to furnace is increasing. In order to solve this problem, such as soundproof considering several feet, but by applying the vibration and noise reduction measures insufficient for the study is Free. In this study, track structure, track, and the inside of the building to support the system, the different forms of neurological history and share about the history cheonanahsan high-speed rail, if passed by the bus stop on the train loads of noise, and the history of interior noise and vibration measurement / analysis of measurement results to assess the relative comparison with the relevant provisions were reviewed. Based on this history, future plans for the design of the bridge to reflect the results of a study is intended to provide information. Waiting for the analysis of vibration and noise reduction, cheonanahsan history passed quietly in the train, on average, appeared to 67.53dB and 65.41dB nervous week on average, were measured with the history. Nervous week waiting room of history and the history cheonanahsan radically different shapes and sizes, so a direct comparison is impossible, but the vibration caused by the disc on the base of the polyurethane elastomer disk is not supported by GERB SYSTEM Waiting more effective in reducing the noise level considered in The main materials for railway and for the localization will help to ensure affordability is considered.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.47-58
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• 2012

Dynamic behaviors of a corrugated steel plate tunnel lining system are examined under wind loads due to passing vehicles. Applied wind loads are simulated by applying the time functions as a vehicle moves through the tunnel. Wind loads are described by the pressure and suction as a vehicle arrives and leaves target positions in the tunnel. The tunnel lining is modeled using the simplified shell elements that retain the characteristics of the corrugated shapes. The displacements of the tunnel lining are evaluated under various conditions regarding wind velocity and the passing vehicles. The responses are found to increase as the vehicle velocity and wind velocity increase. A maximum displacement of 25mm occurs when two vehicles are crossing at the speed of 120km/h. A row of vehicles running consecutively minimally affects the dynamic responses with less than 2.5% of the dynamic responses enlarged and attributed to one running vehicle. It should be noted that the dynamic responses of the tunnel lining should be considered when there is no shotcrete applied.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.187-196
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• 2000

In this paper, stability analysis is carried out for the out of plane behaviors under compressive loads to the direction of the generator in anisotropic cylindrical shells. It is not easy to obtain the analytic solutions about the stability analysis of anisotropic cylindrical shells consisted of composite materials. For solving this problems, this paper used the finite difference method which is one of the numerical methods. Geometrical property of cylindrical shells transforms the compressive loads into the inplane behaviors. This paper studied the change of stiffness in the direction of the circumferential and stability of shells according to change of fiber angle, curvature, subtended angle and aspect ratio. From result of this study, anisotropic cylindrical shells under compressive loads to the direction of the generator vary greatly with respect to the change of the circumferential stiffness. Therefore, it will be more safe to strengthen the circumferential stiffness of anisotropic cylindrical shells under compressive loads.