• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.233-244
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• 2019

Steel jacketing technique is a retrofitting method often employed for static and seismic strengthening of existing reinforced concrete columns. When no continuity is given to angle chords as they cross the floor, the jacket is considered "indirectly loaded", which means that the load acting on the column is transferred partially to the external jacket through interface shear stresses. The evaluation of load transfer mechanism between core and jacket is not straightforward to be modeled, due to the absence of knowledge of a proper constitutive law of the concrete-to-steel interface and to the difficulties in taking into account the mechanical nonlinearities of materials. This paper presents an incremental analytical/numerical approach for evaluating the compressive response of RC columns strengthened with indirectly loaded jackets. The approach allows calculating shear stresses at the interface between core and jacket and predicting the axial capacity of retrofitted columns. A proper constitutive law is proposed for modelling the interaction between the steel and the concrete. Based on plasticity rules and the non-linear behaviour of materials, the column is divided into portions. After a detailed parametric analysis, comparisons are finally made by theoretical predictions and experimental results available in the literature, showing a good agreement.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.749-752
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• 1999

A new interface circuit for variable resistive sensors is proposed. The interface circuit compose of only two strain gages, a voltage-to-current converter, and current mirror with two outputs. A new dual slope A/D converter based on linear operational transconductance amplifier for the testing of prototype interface circuit is also described. The theory of operation is presented and experimental results are used to verify the theoretical predictions. The results show close agreement between predicted behaviour and experimental performance.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.59-67
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• 2009

Three-dimensional (3D) numerical analyses have been conducted to study the behaviour of a single pile to tunnelling. The numerical analysis has included soil slip at the pile-soil interface. In the numerical analyses the interaction between the tunnel and the pile constructed in weathered soil and rock has been analysed. The study includes the pile settlement, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to the tunnel advancement has been rigorously analysed. Due to changes in the relative shear displacement at the pile-soil interface during the tunnel advancement, the shear stress and the axial force distributions along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilised near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour to tunnelling obtained from the numerical analyses will be reported and discussed.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.119-131
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• 2019

Time dependent creep settlements are one of the most important causes of material deteriorations for the huge water structures such as concrete faced rockfill dams (CFRDs). For this reason, performing creep analyses of CFRDs is vital important for monitoring and evaluating of the future and safety of such dams. In this study, it is observed how changes viscoplastic behaviour of a CFR dam depending the time. Ilısu dam that is the longest concrete faced rockfill dam (1775 m) in the world is selected for the three dimensional (3D) analyses. 3D finite difference model of Ilısu dam is modelled using FLAC3D software based on the finite difference method. Two different special creep material models are considered in the numerical analyses. Wipp-creep viscoplastic material model and burger-creep viscoplastic material model were rarely used for the creep analyses of CFRDs in the last are taken into account for the concrete slab and rockfill materials-foundation, respectively. Moreover, interface elements are defined between the concrete slab-rockfill materials and rockfill materials-foundation to provide interaction condition for 3D model. Firstly, dam and foundation are collapsed under its self-weight and static behaviour of the dam is evaluated for the empty reservoir conditions. Then, reservoir water is modelled considering maximum water level of the dam and time-dependent creep analyses are performed for maximum reservoir condition. In this paper, maximum principal stresses, vertical-horizontal displacements and pore pressures that may occur on the dam body surface during 30 years (from 2017 to 2047) are evaluated in detail. According to numerical analyses, empty and maximum reservoir conditions of Ilısu dam are compared with each other in detail. 4 various nodal points are selected under the concrete slab to better seen viscoplastic behaviour changes of the dam and viscoplastic behaviour differences of these points during 30 years are graphically presented. It is clearly seen that horizontal-vertical displacements and principal stresses for maximum reservoir condition are more than the empty reservoir condition of the dam and significant pore pressures are observed during 30 years for maximum reservoir condition. In addition, horizontal-vertical displacements, principal stresses and pore pressures for 4 nodal points obviously increased until a certain time and changes decreased after this time.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2313-2314
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• 2008

In this paper, the behaviour of charge carriers near the metal/polymer interface and its effects on conduction and breakdown phenomena are discussed. The metal/polymer interface strongly affects carrier injection, space charge formation and breakdown phenomena. Based on their experimental results, the physical backgrounds of the interfacial phenomena are explained.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.929-936
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• 2004

A major limitation of available component-based platforms Is that they do not provide suitable means for describing and reasoning on the concurrent behaviour of interacting component-based system. Indeed while these platforms provide convenient ways to describe the typed signatures of components, e.g. like CORBA's IDL, they offer a quite low-level support to describe the concurrent behaviour of component. The ability to describe and verify the concurrent behaviour of interacting components is key aspect In the development of large component-based software system. This study propose a component interface specification using process algebra and configuration's role which allows one to prove correctness of software architecture generated at design level as well as to define compatibility relations by our evolution rule and $\pi$-graph. Also, we shown on an appropriateness of a specification techniques and definitions proposed in this paper by case-study.

• Journal of Adhesion and Interface
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• v.5 no.2
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• pp.5-14
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• 2004

Since flexible adhesives are used more and more in structural applications, designers should have a better understanding of its behaviour under various conditions as ultimate load, fatigue load, long-term load and environmental conditions. This paper focuses on long-term load conditions and its effect on flexible adhesives. The creep properties of both PU (PolyUrethane) and SMP (Silyl Modified Polymers) adhesives used for identical applications are considered. To investigate the creep behaviour tests under various conditions were done. The results of those tests are presented and compared. To evaluate these results an empirical method is proposed and discussed. An example illustrates the potential of this method. It is also shown that with use of a probabilistic calibration technique this method results into a simple rule, which can be used to calculate the creep for practical applications. For the studied adhesives, the creep performance of the SMP adhesive is shown to be of the same level or slightly better than of the two PU adhesives. In addition to this empirical method, the principles of a more complex theoretical based method are introduced. The potential of this method is illustrated and future research activities are drawn.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.147-152
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• 2003

The purpose of this paper is to develope an understanding of fundamental mechanism of shear behaviour between granite and concrete interfaces. The interface of pile socketed in rock can be modeled in laboratory tests by resolving the axisymmetric pile situation into the two dimensional situation under CNS(constant normal stiffness) direct shear condition. In this paper, the granite core samples were used to simulate the interface condition of piles socketed In granite. The samples were prepared in the laboratory to simulate field condition, roughness(angle, height), stress boundary condition, and then tested by CNS direct shear tests. This paper gives some points about shearing behaviour of socket piles into domestic granite through the analysis of CNS tests results.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.11a
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• pp.75-81
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• 1995

DYLAM and its related applications are reviewed in detail and found to have many favourable characteristics. Concerning human factor analysis, the study demonstrates that DYLAM methodology represents an appropriate tool to study man-machine behaviour provided that DYLAM is used to model machine behaviour and an appropriate operator interface human factor model is included. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neural network predicative model, is implemented and used to analyse dynamically the CANDU pressurizer system.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.27-34
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• 2010

A finite element analysis has been conducted to clarify the behaviour of a single pile in heaving ground related to ground excavation. The numerical analysis has included soil slip at the pile-soil interface, analysing the interaction between the pile and the clay has been studied. The study includes the upward movement of the pile, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to a decrease in the vertical soil stress has been rigorously analysed. Due to the reductions in the vertical soil stress after excavation, the relative shear displacement and the shear stress along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilized near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour in heaving ground analysed from the numerical analyses has been reported.