• Wind and Structures
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• v.30 no.4
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• pp.423-432
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• 2020

A steel high-rise building (HRB) with 15 stories was analyzed under the dynamic load of wind or four different earthquakes taking into consideration the effect of soil-structure interaction (SSI) and using tuned mass damper (TMD) devices to resist these types of dynamic loads. The behavior of the steel HRB as a lightweight structure subjected to dynamic loads is critical especially for wind load with effect maximum at the top of the building and reduced until the base of the building, while on the contrary for seismic load with effect maximum at the base and reduced until the top of the building. The TMDs as a successful passive resistance method against the effect of wind or earthquakes is used to mitigate their effects on the steel high-rise building. Lateral displacements, top accelerations and straining actions were computed to judge the effectiveness of the TMDs on the response of the steel HRB subjected to wind or earthquakes.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.393-406
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• 1993

In resistance spot welding process, size of molten nuggest have been utilized to assess the integrity of the weld quality. However real-time monitoring of the nugget size is an extremely difficult problem. This paper describes the design of an artificial neural networks(ANN) estimator to predict the nugget size for on-line use of weld quality monitoring. The main task of the ANN estimator is to realize the mapping characteristics from the sampled dynamic resistance signal to the actual negget size through training. The structure of the ANN estimator including the number of hidden layers and nodes in a layer is determined by an estimation error analysis. A series of welding experiments are performed to assess the performance of the ANN estimator. The results are quite promissing in that real-time estimation of the invisible nugget size can be achieved by analyzing the dynamic resistance signal without any conventional destructive testing of welds.

• International journal of steel structures
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• v.18 no.4
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• pp.1306-1317
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• 2018

For determining the in-plane buckling resistance of a concrete-filled steel tubular (CFST) arch, the current technical code GB50923-2013 specifies the use of an equivalent beam-column method which ignores the effect of rise-to-span ratio. This may induce a gap between the calculated result and actual stability capacity. In this study, a FE model is used to predict the buckling behavior of CFST truss arches subjected to uniformly distributed loads. The influence of rise-to-span ratio on the capacity of truss arches is investigated, and it is found that the stability capacity reduces as rise-to-span ratio declines. Besides, the calculations of equivalent slenderness ratio for different truss sections are made to consider the effect of shear deformation. Moreover, based on FE results, a new design equation is proposed to predict the in-plane strength of CFST parabolic truss arches under uniformly distributed loads.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.43-51
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• 2017

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.867-875
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• 2014

Planing crafts were specifically designed to achieve relatively high speeds on the water. When a planing craft is running at high speed, dynamic pressure on the bottom makes the boat rise on the surface of the water. This reduces the area of the sinking surface of the boat to increase air resistance. Air resistance means the resistance that occurs when the hull and deck house over the surface of the water come in contact with the air current. In this paper, we carried out a CFD numerical analysis to find optimal deck houses that decreased air-resistance on the water when planing crafts are running at high speed. We finally developed the deck house shape of high-speed planing crafts that optimally decreased air resistance.

• Structural Engineering and Mechanics
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• v.8 no.5
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• pp.477-490
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• 1999

The uncertainties associated with structural parameters and dynamic loading are identified and discussed. Structural parametric uncertainties are treated as random variables and dynamic wind load is simulated as a random process. Dynamic wind-induced responses of structures with parametric uncertainties are investigated by using stochastic finite element method. The formulas for structural dynamic reliability analysis considering the randomness of structural resistance and loading are proposed. Two numerical examples of high-rise structures are presented to illustrate the proposed methodology. The calculated results demonstrate that the variation in structural parameters indeed influences the dynamic response and the first passage probability evaluation of structures.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.243-257
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• 2016

The aim of this study is to investigate the seismic resistance of dry stone arches under in-plane seismic loading. For that purpose, several numerical analyses were performed using the combined finite-discrete element method (FDEM). Twelve types of arches with different ratios of a rise at the mid-span to the span, different thicknesses of stone blocks and different numbers of stone blocks in the arch were subjected to an incremental dynamic analysis based on excitation from three real horizontal and vertical ground motions. The minimum value of the failure peak ground acceleration that caused the collapse of the arch was adopted as a measure of the seismic resistance. In this study, the collapse mechanisms of each type of stone arch, as well as the influence of the geometry of stone blocks and stone arches on the seismic resistance of structures were observed. The conclusions obtained on the basis of the performed numerical analyses can be used as guidelines for the design of dry stone arches.

• Steel and Composite Structures
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• v.37 no.4
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• pp.447-462
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• 2020

In this paper, a simplified seismic design method for low-rise dual frame-steel plate shear wall (SPSW) structures is proposed in the framework of performance-based seismic design. The dynamic response of a low-rise structure is mainly dominated by the first-mode and the structural system can be simplified to an equivalent single degree-of-freedom (SDOF) oscillator. The dual frame-SPSW structure was decomposed into a frame system and a SPSW system and they were simplified to an equivalent F-SDOF (SDOF for frame) oscillator and an equivalent S-SDOF (SDOF for SPSW) oscillator, respectively. The analytical models of F-SDOF and S-SDOF oscillators were constructed based on the OpenSees platform. The equivalent SDOF oscillator (D-SDOF, dual SDOF) for the frame-SPSW system was developed by combining the F-SDOF and S-SDOF oscillators in parallel. By employing the lateral force resistance coefficients and seismic demands of D-SDOF oscillator, the design approach of SPSW systems was developed. A 7-story frame-SPSW system was adopted to verify the feasibility and demonstrate the design process of the simplified method. The results also show the seismic demands derived by the equivalent dual SDOF oscillator have a good consistence with that by the frame-SPSW structure.

• Journal of Advanced Engineering and Technology
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• v.11 no.4
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• pp.279-285
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• 2018

A shear connection between the steel beam and concrete slab determines the stability of composite beams. An extensive numerical study to evaluate the resistance of the shear connection in a solid slab at high temperature was conducted. Three-dimensional thermo-mechanical finite element models were developed using a dynamic explicit method and concrete damaged plasticity model. Temperature-dependent plasticity parameters of the concrete model were proposed, and the accuracy of the developed model was obtained against experimental data. This investigation has revealed that a stud shearing failure occurs regardless of temperatures, and its shearing location changes in accordance with a rise in temperature. A new strength reduction formula has been presented to estimate the resistance of the shear connection at high temperatures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.140-143
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• 2006

Load/Unload(L/UL) technology includes the benefits, that is, increased areal density, reduced power consumption and improved shock resistance. The main issues of L/UL are no slider-disk contact and no media damage. To make sure L/UL stability, we consider many design parameters in L/UL systems. This paper is focused on disk design parameters through designing a disk bump in outer guard band(OGB). In the case of bump design on the disk, we create a bump by changing bump design parameters as like size and amplitude. From dynamic analysis, we choose optimal bump model with the highest flying height and the longest rising time. When a slider passes over a bump in dynamic system, the slider rise above bump according to bump shape. On the basis of this rising effect on the bump, we apply bump design to classical L/UL system having slider-disk contact possibility. This study is based on the simulation, we finally realize improved slider unloading performance by applying slider dynamic result on unload simulation.