• Smart Structures and Systems
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• v.4 no.5
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• pp.685-696
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• 2008

This paper deals with the numerical model of a bracing-friction damper system and its deployment using the optimal slip load distribution for the seismic retrofitting of a damaged building. The Slotted Bolted Connection (SBC) type friction damper system was tested to investigate its energy dissipation characteristic. Test results coincided with the numerical ones using the conventional model of a bracing-friction damper system. The placement of this device was numerically explored to apply it to the assumed damaged-building and to evaluate its efficiency. It was found by distributing the slip load that minimizes the given performance indicies based on structural response. Numerical results for the damaged building retrofitted with this slip load distribution showed that the seismic design of the bracing-friction damper system under consideration is effective for the structural response reduction.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1259-1281
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• 2014

This research has been conducted in order to investigate the effects of peak ground velocity (PGV) of near-field earthquakes on base-isolated structures mounted on Single Friction Pendulum (SFP), Double Concave Friction Pendulum (DCFP) and Triple Concave Friction Pendulum (TCFP) bearings. Seismic responses of base-isolated structures subjected to simplified near field pulses including the forward directivity and the fling step pulses are considered in this study. Behaviour of a two dimensional single story structure mounting on SFP, DCFP and TCFP isolators investigated employing a variety range of isolators and the velocity (PGV) of the forward directivity and the fling step pulses as the main variables of the near field earthquakes. The maximum isolator displacement and base shear are selected as main seismic responses. Peak seismic responses of different isolator types are compared to emphasize the efficiency of each one under near field earthquakes. It is demonstrated that rising the PGVs increases the isolator displacement and base shear of structure. The effects of the forward directivity are greater than the fling step pulses. Furthermore, TCFP isolator is more effective to control the near field effects than the other friction pendulum isolators are. This efficiency is more significant in pulses with longer period and greater PGVs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.389-394
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• 2011

Existing FPS(Friction Pendulum System) is isolation system which is possible to isolate structures by pendulum characteristic from ground vibration. Structural natural frequency could be decided by designing the radius of curvature of FPS. Thus, response vibration could be reduced by changing natural frequency of structures from FPS. But effective periods of recorded seismic wave were various and estimation of earthquake characteristic could be difficult. If effective periods of seismic wave correspond to natural frequency of structures with FPS, resonance can be occurred. Therefore, CFPBS(Cone-type Friction Pendulum Bearing System) was developed for controlling the response acceleration and displacement by the slope of friction surfaces. Structural natural frequency with CFPBS can be changed according to position of ball on the friction surface which was designed cone-type. Therefore, Divergence of response could be controlled by CFPBS which had constantly changing natural frequency with low modal participation factor in wide-range. In this study, Seismic performance of CFPBS was evaluated by numerical analysis and shaking table test.

• Journal of Korean Association for Spatial Structures
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• v.16 no.4
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• pp.83-89
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• 2016

Middle size of membrane retractable roof is under 25m span which consists of various moving systems. Trolley is the system that leads the membrane to parking place, transferring the load from the membrane to structural cable. When membrane closes roof completely, thus, structural behavior of trolley, which may contain various material with different friction coefficients, should be investigated by vertical load. Nummerical simulation of trolley prototypes, in this research, was performed by incrementation of vertical load. Consequently, this paper studied proper friction characteristics and provided the effective inner materials of trolley.

• Structural Engineering and Mechanics
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• v.22 no.5
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• pp.517-539
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• 2006

Friction problems involving rubber components are frequently encountered in industrial applications. Their treatment within the framework of numerical simulations by means of the Finite Element Method (FEM) is the main issue of this paper. Special emphasis is placed on the choice of a suitable material model and the formulation of a contact model specially designed for the particular characteristics of rubber friction. A coupled thermomechanical approach allows for consideration of the influence of temperature on the frictional behavior. The developed tools are implemented in the commercial FE code ABAQUS. They are validated taking the sliding motion of a rubber tread block as example. Such simulations are frequently encountered in tire design and development. The simulations are carried out with different formulations for the material and the frictional behavior. Comparison of the obtained results with experimental observations enables to judge the suitability of the applied formulations on a structural scale.

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.74-78
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• 2010

In this paper, 2-axis driving mechanism, which uses voice coil motor (VCM), is proposed to measure the friction force. The proposed VCM actuator consists of two parts; structural part and magnetic circuit part. Structural part is simplified to perform the friction experiments. Magnetic circuit part is composed of two parts. The experiments are accomplished by changing the mass of moving part. Through the experiments, optimal dimension is selected. Finally, the experimental results are verified and the optimal case is applied to the 2-axis driving mechanism, optical image stabilization actuator.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.95-102
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• 2017

The friction pendulum system(FPS) is a kind of seismic isolation devices for isolating structures from an earthquake. To analyze the effect of friction materials used in the friction pendulum system, fragility analysis of LNG tank with seismic isolation system was conducted. In this study, titanium dioxide($TiO_2$) nanoparticles were incorporated into polyvinylidene fluoride(PVDF) matrix to produce friction materials attached to the FPS. The base moment of the concrete outer tank and the acceleration of the structure were evaluated from different mixing ratios of constituents for the friction materials. The seismic fragility curves were developed based on two types of limit state. It is confirmed that evaluation of combined fragility curves with several limit states can be applied to select the optimum friction material satisfying the required performance of the FPS for various infrastructure.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.242-243
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• 2009

Friction stir welding and friction stir processing is a new solid state processing technique for ioining and micro..structural modification in metallic materials. It has been applied not only joining for light metals but also modification of the microstructure to enhance mechanical properties. In thin study, we investigated the mechanical properties for applied friction stir welding and processing under various parameters such as probe diameter, probe type, traveling speed and rotating speed for 5456-H116 AI allov. As a result of experiments, optimum condition of friction stir welding is traveling speed of 15mm/min, rotating speed of 500RPM at 6mm diameter probe. Moreover, in the case of friction stir processing, the optimum condition is traveling speed of 15mm/min, rotating speed of 250RPM at full screw probe. As above mentioned, the mechanical characteristics enhanced with the decreasing of traveling speed and the increasing of friction areas because of plastic flow due to high friction heat. These result can be used as reference data for ship repairment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3502-3507
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• 2013

If a sky-bridge is rigidly connected to adjacent buildings, the irregularity of the connected structures is increased resulting in providing a worse seismic behavior. Therefore, a friction pendulum system (FPS) or lead rubber bearing (LRB) is frequently used for the connection system between a sky-bridge and building structures. These connection systems should be carefully designed to prevent a skyfall of a sky-bridge subjected to severe seismic loads. In this paper, the inevitable structural design procedures for a sky-bridge connection system using a friction pendulum system without uplift resistance capacity have been investigated. To this end, Nuri Dream Square building structure is used as a example structure. The structural design process of a friction pendulum system for fail safe of a sky-bridge has been proposed in this paper by evaluating structural responses of the sky-bridge and building structures subjected to earthquake loads.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.131-138
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• 2006

Structural bracing concept equipped with a new and efficient friction based energy dissipation device is referred to Friction SliP Brace (FSB) where the behavior of the brace components is elastic until the axial resistant force in the brace exceeds the friction force developed at the frictional interface of the device. In this study, the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction SliP Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The clamping action regulated by the developed algorithm is altered during the response of the building. The results indicate that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage. Providing predetermined constant incremental strengths to the building by AFSB medium improves response by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations.