• Earthquakes and Structures
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• v.27 no.4
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• pp.331-344
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• 2024

The performance of reinforced concrete buildings subjected to earthquake excitations depends on the structural behaviour of the superstructure as well as the type of foundation and the properties of soil on which the structure is founded. The consideration of the effects due to the interaction between the structure and soil- foundation alters the seismic response of reinforced concrete buildings subjected to earthquake motion. Evaluation of the structural response of buildings for quantitative assessment of the seismic fragility has been a demanding problem for the engineers. Present research deals with development of fragility curve for building specific vulnerability assessment based on different damage parameters considering the effect of soil-structure interaction. Incremental Dynamic Analysis of fixed base and flexible base RC building models founded on different soil conditions was conducted using finite element software. Three sets of fragility curves were developed with maximum roof displacement, inter storey drift and plastic energy dissipated as engineering demand parameters. The results indicated an increase in the likelihood of exceeding various damage limits by 10-40% for flexible base condition with soft soil profiles. Fragility curve based on energy dissipated showed a higher probability of exceedance for collapse prevention damage limit whereas for lower damage states, conventional methods showed higher probability of exceedance. With plastic energy dissipated as engineering demand parameter, it is possible to track down the intensity of earthquake at which the plastic deformation starts, thereby providing an accurate vulnerability assessment of the structure. Fragility modification factors that enable the transformation of existing fragility curves to account for Soil-Structure Interaction effects based on different damage measures are proposed for different soil conditions to facilitate a congenial vulnerability assessment for buildings with flexible base conditions.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.59-64
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• 2018

The damages to the reinforced earth retaining wall are divided into the front wall, foundation, drainage and upper slope. Damage of reinforced earth retaining wall is mainly caused by damage caused by drainage problem in the field. Recently, damage caused by snow removal materials have been occurred. Recently, the amount of snow removal materials used in winter is increasing due to abnormal weather. This chlorides degrades the concrete structure, where the reinforced earth retaining wall was no exception. There has recently been a case in which the front wall of the reinforced earth retaining wall deteriorates due to the chlorides introduced into the back filling portion through the drainage passage. Therefore, in this study, the cause of damages of reinforced earth retaining wall constructed in bridge abutment was analyzed, and an analytical study was conducted on the countermeasure. As a result, it was found that chlorides, which was introduced through the drainage system in the expansion joint of the bridge shift part or the upper structure, is infiltrated into the back part of the reinforced earth retaining wall and damaged. Therefore, it is suggested to improve the drainage system and restored the stiffness of the front wall.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.15-23
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• 2006

Sand Compaction Pile and Stone Column method have been used in widely during several decades as a technique to reinforce soft soils and increasing ultimate bearing capacity, accelerate consolidation settlement of the foundation ground. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, development the geogrid reinforced stone column system for settlement reduction and wide range of application of stone columns. To develop this system, triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate and confine pressure. Then, 3-dimensional numerical analysis were evaluated for application of the GRSC (geogrid reinforced stone column) system as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on types and reinforcing depth change of geogrid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.15-20
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• 2019

This paper evaluated the construction costs of 11 design cases to decrease the horizontal forces applied to the abutment. They include two abutment types, which are to improve backfill materials for a reversed T-shaped abutment and geosynthetic Reinforced Abutment for Railways (RAR). The first type of economic analysis was that the internal friction angles of backfill materials were increased from Φ=35° to Φ=40° and 50° for a reversed T-shaped abutment. In addition, the second type was the cases with the design of geosynthetic RAR. When friction angles of 40° or 50° were applied through the improvement of the backfill material, the decrease in construction cost of the abutment was not large (2.0~3.9%), even though the horizontal forces applied to the abutment had decreased to 18~48%. In the case of applying the RAR, however, a maximum 30% cost reduction was evaluated by the decrease in horizontal force to "0" theoretically. The cost reduction resulted from the decrease in wall thickness, base slab size, and number and material change of pile foundation for the abutment.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.5-14
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• 2007

The purpose of this study is to evaluate the normalized behaviors of existing bridge foundations reinforced by micropiles. In order to do numerical method a finite element program was used to predict the micropile behavior and quantify their reinforcing effects on existing bridge foundations. In addition, the installation effects of battered micropiles on existing foundations were compared with vertically reinforced bridge foundations. Based on the study performed, it was found that the use of battered micropiles more efficiently reduces displacement of existing foundations than vertically installed micropiles under vertical and horizontal loadings, respectively. The batter angle of micropiles was also found to be most effective at about $15^{\circ}{\sim}20^{\circ}$ in reducing the vertical displacement. The horizontal reinforcing effect continues to be larger with an increase in batter angles. So, it is believed that the results presented could give an idea to enhance In-service performance of existing bridge foundations reinforced by micropiles.

• Advances in nano research
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• v.16 no.6
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• pp.623-638
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• 2024

This study investigates the thermal post-buckling behavior of concrete eccentric annular sector plates reinforced with graphene oxide powders (GOPs). Employing the minimum total potential energy principle, the plates' stability and response under thermal loads are analyzed. The Haber-Schaim foundation model is utilized to account for the support conditions, while the transform differential quadrature method (TDQM) is applied to solve the governing differential equations efficiently. The integration of GOPs significantly enhances the mechanical properties and stability of the plates, making them suitable for advanced engineering applications. Numerical results demonstrate the critical thermal loads and post-buckling paths, providing valuable insights into the design and optimization of such reinforced structures. This study presents a machine learning algorithm designed to predict complex engineering phenomena using datasets derived from presented mathematical modeling. By leveraging advanced data analytics and machine learning techniques, the algorithm effectively captures and learns intricate patterns from the mathematical models, providing accurate and efficient predictions. The methodology involves generating comprehensive datasets from mathematical simulations, which are then used to train the machine learning model. The trained model is capable of predicting various engineering outcomes, such as stress, strain, and thermal responses, with high precision. This approach significantly reduces the computational time and resources required for traditional simulations, enabling rapid and reliable analysis. This comprehensive approach offers a robust framework for predicting the thermal post-buckling behavior of reinforced concrete plates, contributing to the development of resilient and efficient structural components in civil engineering.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1607-1614
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• 2011

As the connection between spread footing and pile is very important structural connection, it acts as the inter-loading medium to transfer the rail loads applied by superstructure to ground through the body pile of foundation. The experimental study is the method how to reinforce the pile cap between steel pile and footing utilizing perfobond plate with protruding keys. It were experimented on the compression punching tests and bending moment tests against the vertical loading and horizontal loadings acting on head of steel tube pipe. As a result, the tension capacity of the perfobond plate exhibited the superior performance due to the interlocking or dowel effects by the sheared keys of perfobond plate, and there were showing the sufficient strength and ductile capacity against the bending moment of horizontal loading tests. Therefore, it is judged that "the embedded method of perfobond plate in pile cap and footing" which is utilizing the shear connection of perfobond plate with protruding keys has a sufficient structural stability enough to be replaced with the current specification of reinforced method of pile cap with vertically deformed rebar against the vertical compression loads and bending moments that are able to occur in the combination structure of steel pile and the footing foundation.

• Computers and Concrete
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• v.20 no.2
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• pp.119-127
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• 2017

Time-dependent buckling of embedded straight concrete columns armed with Silicon dioxide($SiO_2$) nano-particles exposed to fire is investigated in the present study for the fire time. The column is simulated mathematically with Timoshenko beam model. The governing mass conservation equations to describe heat and moisture transport in concrete containing free water, water vapor, and dry air in conjunction with the conversion of energy are considered. The characteristics of the equivalent composite are determined using Mori-Tanaka approach. The foundation around the column is simulated with spring and shear layer. Employing nonlinear strains-displacements, energy methods and Hamilton's principal, the governing equations are derived. Differential quadrature method (DQM) is used in order to obtain the critical buckling load and critical buckling time of structure. The influences of volume percent of $SiO_2nano-particles$, geometrical parameters, elastic foundation and concrete porosity are investigated on the time-dependent buckling behaviours of structure. Numerical results indicate that reinforcing the concrete column with $SiO_2nano-particles$, the structure becomes stiffer and the critical buckling load and time increase.

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.71-80
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• 2001

The quantitative analysis of bearing capacity with stone column-mat is not ease because the bearing capacity of stone column is affected by so many parameters. The bearing capacity of stone column is mainly governed by horizontal resistance along the interface with soil. Also, this foundation system is affected by geometric factors such as column spacing, embedment ratio and failure surface inclination. Therefore, in this study, critical length and the effect of failure surface inclination was studied with single and group end bearing stone columns by loading tests. Results of model tests are compared to the present theoretical methods and are examined with FEM analysis.

• Smart Structures and Systems
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• v.22 no.1
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• pp.105-120
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• 2018

In this paper, the nonlinear free and forced vibration responses of sandwich nano-beams with three various functionally graded (FG) patterns of reinforced carbon nanotubes (CNTs) face-sheets are investigated. The sandwich nano-beam is resting on nonlinear Visco-elastic foundation and is subjected to thermal and electrical loads. The nonlinear governing equations of motion are derived for an Euler-Bernoulli beam based on Hamilton principle and von Karman nonlinear relation. To analyze nonlinear vibration, Galerkin's decomposition technique is employed to convert the governing partial differential equation (PDE) to a nonlinear ordinary differential equation (ODE). Furthermore, the Multiple Times Scale (MTS) method is employed to find approximate solution for the nonlinear time, frequency and forced responses of the sandwich nano-beam. Comparison between results of this paper and previous published paper shows that our numerical results are in good agreement with literature. In addition, the nonlinear frequency, force response and nonlinear damping time response is carefully studied. The influences of important parameters such as nonlocal parameter, volume fraction of the CNTs, different patterns of CNTs, length scale parameter, Visco-Pasternak foundation parameter, applied voltage, longitudinal magnetic field and temperature change are investigated on the various responses. One can conclude that frequency of FG-AV pattern is greater than other used patterns.