• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.95-100
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• 2011

Currently, office buildings in Korea tend to adopt as their outer wall the curtain wall structure which can be easily constructed and has beautiful external appearance as well. However, the problem is that the curtain wall structure does not have a uniform composition unlike the wall of existing reinforced concrete structures and has a frame made of metal with high heat conduction. Therefore, it is expected that the structure will be highly influenced by the thermal bridge. Thereupon, this study analyzes how to set up the composition of the wall system and heat transmission rate in consideration of the thermal characteristics of the curtain wall structure and applies it in practice by simulation in order to propose a guideline for the energy simulation method of the curtain wall structure and analyze its differences from existing simulation methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.157-158
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• 2009

In this study, We analyze structural behavior feature of column under reinforced-bar and concrete strength and load conditions and analyze optimal column diameter and construction cost through parameter study. In case we use the 40MPa high strength concrete instead of 27MPa concrete in pier, the results show positive effect in appearance of pier and cost because of small column diameter and low construction cost. Also, practical effect is proved by applying this results in pier of Shin Hou Bridge on Hum-Sung ${\sim}$ Chung-Ju highway construction work.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.

• Structural Engineering and Mechanics
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• v.75 no.1
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• pp.19-32
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• 2020

Due to repetitive traffic loadings and environmental attacks, reinforced concrete (RC) bridge deck slabs are suffering from severe degradation, which makes structural repairing an urgency. In this study, the fatigue performance of an RC bridge deck repairing technique using ultra-high performance fiber reinforcement concrete (UHPFRC) overlay is assessed experimentally with a wheel-type loading set-up as well as analytically based on finite element method (FEM) using a crack bridging degradation concept. In both approaches, an original RC slab is firstly preloaded to achieve a partly damaged RC slab which is then repaired with UHPFRC overlay and reloaded. The results indicate that the developed analytical method can predict the experimental fatigue behaviors including displacement evolutions and crack patterns reasonably well. In addition, as the shear stress in the concrete/UHPFRC interface stays relatively low over the calculations, this interface can be simply simulated as perfect. Moreover, superior to the experiments, the numerical method provides fatigue behaviors of not only the repaired but also the unrepaired RC slabs. Due to the high strengths and cracking resistance of UHPFRC, the repaired slab exhibited a decelerated deterioration rate and an extended fatigue life compared with the unrepaired slab. Therefore, the proposed repairing scheme can afford significant strengthen effects and act as a reference for future practices and engineering applications.

• Computers and Concrete
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• v.21 no.4
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• pp.471-484
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• 2018

Refined analysis depicting mass transportation and physicochemical reaction and reasonable computing load with acceptable DOFs are the two major challenges of numerical simulation for concrete durability. Mesoscopic numerical simulation for chloride diffusion considering binder, aggregate and interfacial transition zone is unable to be expended to the full structure due to huge number of DOFs. In this paper, a multiscale approach of combining both mesoscopic model including full-graded aggregate and equivalent macroscopic model was introduced. An equivalent conversion of chloride content at the Interfacial Transition Layer (ITL) connecting both models was considered. Feasibility and relative error were discussed by analytical deduction and numerical simulation. Case study clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Difference for single-scale simulation and multiscale approach was observed. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of rebar placement, rebar diameter, concrete cover and exposure period.

• Journal of KIBIM
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• v.4 no.3
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• pp.1-9
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• 2014

As BIM application continues to increase in civil engineering, in this study, 3D information model for RC(Reinforced Concrete) bridge pylon was developed and verified its effectiveness at the structural-design stage. To define 3D information model of RC A-Type pylon, characteristics of pylon were analyzed and 3D model structure was constructed. The 3D information model, one of the core product of BIM, manages all information generated during all life-cycle of a structure and consequently maximizes the efficiency of utilizing information. Also, this study proposes interface module between input data in structural analysis and 3D model of RC pylon. The module can create the input data for non-linear structural analysis. It is essential to study on method of developing 3D information model and propose a structural analysis model by utilizing 3D model for the effective use of BIM techniques in construction industry. The results of this study can be used as the base data for developing the 3D information model of RC pylon in the structural analysis field.

• Structural Engineering and Mechanics
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• v.15 no.6
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• pp.629-651
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• 2003

Current design specifications prescribe that the upper and lower reinforcement mat is required in the same amount to resist negative and positive moment in bridge decks. This design concept is primarily based on the unrealistic assumption that the girder plays a role of rigid support against deck deflection. In reality, however, girders are flexible and the deflection of girders affect the behavior of deck slabs. In the present study, an analytical method was developed to take the effect of the girder flexibility on the deck behavior into account. The method was formulated based on the slope-deflection equations of plates and harmonic analysis. Unlike the conventional finite element analysis, the input and output schemes are simple and convenient. The validity of the presented study was verified by a series of comparative studies with finite element analyses and experimental tests. It was shown from the analyses that the negative transverse moments of decks were significantly reduced in many cases when the girder flexibility were appropriately taken into consideration whereas the positive moments tend to increase. This poses a strong need to improve the conventional design concept of decks on rigid girders to those on flexible girders.

• Structural Engineering and Mechanics
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• v.31 no.5
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• pp.545-566
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• 2009

Bridge columns are subjected to combined actions of axial force, shear force and bending moment during earthquakes, caused by spatially-complex earthquake motions, features of structural configurations and the interaction between input and response characteristics. Combined actions can have significant effects on the force and deformation capacity of RC columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. This paper evaluates the seismic response of three prototype reinforced concrete bridges using comprehensive numerical models that are capable of simulating the complex soil-structural interaction effects and nonlinear behavior of columns. An analytical approach that can capture the shear-flexural interacting behavior is developed to model the realistic nonlinear behavior of RC columns, including the pinching behavior, strength deterioration and stiffness softening due to combined actions of shear force, axial force and bending moment. Seismic response analyses were conducted on the prototype bridges under suites of ground motions. Response quantities of bridges (e.g., drift, acceleration, section force and section moment etc.) are compared and evaluated to identify the effects of vertical motion, structural characteristics and the shear-flexural interaction on seismic demand of bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.227-236
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• 2002

The purpose of this study makes a retrofit and rehabilitation practice trough the analysis and the improvement for the underlying problem of current retrofit and rehabilitation methods. Therefore, the deterioration process, the damage cause, the condition classification, the fatigue mechanism and the applied quantity of strengthening methods for RC deck slabs were analyzed. Artificial neural networks are efficient computing techniques that are widely used to solve complex problems in many fields. In this study, a back-propagation neural network model for estimating a management on existing reinforced concrete bridge decks from damage cause, damage type, and integrity assessment at the initial stage is need. The training and testing of the network were based on a database of 36. Four different network models were used to study the ability of the neural network to predict the desirable output of increasing degree of accuracy. The neural networks is trained by modifying the weights of the neurons in response to the errors between the actual output values and the target output value. Training was done iteratively until the average sum squared errors over all the training patterns were minimized. This generally occurred after about 5,000 cycles of training.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.247-254
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• 2010

Due to lightweight and high durability of glass-fiber reinforced polyester (GFRP) materials, they are promising alternatives to conventional construction materials such as steel, concrete and wood. As good application examples of GFRP materials, several types of temporary arch bridges were suggested and verified by finite element analyses in our previous study where snap-fit GFRP decks were applied. In this paper, we conduct a structural performance test to verify safety and serviceability of the temporary arch bridge, where snap-fit GFRP decks are assembled by bolts. The structural problems occurred in this test are also discussed and improvement of temporary arch bridges is suggested to resolve the occurred structural problems.