• 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 Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.111-114
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• 2005

This paper presents a comparison of experimental value by hemispherical grounding simulation system and calculated value by CDEGS program for ground potential rise of structure. When a test current flowed through structure grounding electrodes, ground potential rise was measured and analyzed for types of structure using the hemispherical grounding simulation system in real time, and was computed by means of CDEGS program. The model structures were designed and fabricated with two types on a scale of one-one hundred sixty. When the experimental data were compared with the theoretical values, the similar profile was shown. Therefore, the confidence of measurement was obtained. The distributions of ground surface potential are dependent on the resistivity and absorption percentage in concrete attached to structure.

• Coupled systems mechanics
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• v.7 no.3
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• pp.281-295
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• 2018

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

• Coupled systems mechanics
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• v.6 no.4
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• pp.523-537
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• 2017

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

• Advances in concrete construction
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• v.9 no.3
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• pp.235-248
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• 2020

Progressive collapse in a structure occurs when load bearing members are failed and the adjoining structural elements cannot resist the redistributed forces and fails subsequently, that leads to complete collapse of structure. Recently, construction using precast concrete technology is adopted increasingly because it offers many advantages like faster construction, less requirement of skilled labours at site, reduced formwork and scaffolding, massive production with reduced amount of construction waste, better quality and better surface finishing as compared to conventional reinforced concrete construction. Connections are the critical elements for any precast structure, because in past, major collapse of precast structure took place because of connection failure. In this study, behavior of four different precast wet connections with U shaped reinforcement bars provided at different locations is evaluated. Reduced 1/3^rd scale precast beam column assemblies having two span beam and three columns with removed middle column are constructed and examined by performing experiments. The response of precast connections is compared with monolithic connection, under column removal scenario. The connection region of test specimens are filled by cast-in-place micro concrete with and without polypropylene fibers. Performance of specimen is evaluated on the basis of ultimate load carrying capacity, maximum deflection at the location of removed middle column, crack formation and failure propagation. Further, Finite element (FE) analysis is carried out for validation of experimental studies and understanding the performance of structural components. Monolithic and precast beam column assemblies are modeled using non-linear Finite Element (FE) analysis based software ABAQUS. Actual experimental conditions are simulated using appropriate boundary and loading conditions. Finite Element simulation results in terms of load versus deflection are compared with that of experimental study. The nonlinear FE analysis results shows good agreement with experimental results.

• The Korean Journal of Ceramics
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• v.6 no.1
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• pp.1-5
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• 2000

Particle packing properties are important to develop high technology products in the field of cement and concrete. Two types of particle packing models for aggregates with sand and cement were introduced: the loose and the dense aggregate packing. Aggregate packing models with randomly generated sand and cement particles in the interstices of aggregates fit the Furnas model very well. Different aggregate models show different packing properties with the experimental results. Main reason for the difference with the experimental results is due to sand rearrangement in the loose aggregate packing model and to aggregate relaxation in the dense aggregate packing model. In the experimental situation, aggregates seem to be more disordered and have a relaxed packing structure in the dense packing, and sands seem to have a more rearranged packing structure in the loose packing model.

• Computers and Concrete
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• v.27 no.4
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• pp.385-393
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• 2021

Reinforcement corrosion is the main cause of the durability failure of reinforced concrete (RC) structure. In this paper, a three-dimensional (3D) numerical model of macro-cell corrosion is established to reveal the corrosion mechanisms of steel reinforcement in RC structure. Modified Direct Iteration Method (MDIM) is employed to solve the system of partial differential equations for reinforcement corrosion. Through the sensitivity analysis of electrochemical parameters, it is found that the average corrosion current density is more sensitive to the change of cathodic Tafel slope and anodic equilibrium potential, compared with the other electrochemical parameters. Furthermore, both the anode-to-cathode (A/C) ratio and the anodic length have significant influences on the average corrosion current density, especially when A/C ratio is less than 0.5 and anodic length is less than 35 mm. More importantly, it is demonstrated that the corrosion rate of semi-circumferential corrosion is much larger than that of circumferential corrosion for the same A/C ratio value. The simulation results can give a unique insight into understanding the detailed electrochemical corrosion processes of steel reinforcement in RC structure for application in service life prediction of RC structures in actual civil engineer.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.283-293
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• 2016

Owing to an increase in the air tightness of recent buildings, the natural ventilation rate was significantly lowered and the removal of accumulated moisture became difficult in these buildings. The hygrothermal performance of these buildings should be carefully considered to provide comfortable indoor environment by removing the moisture condensation risk and the mold growth potential. In this study, hygrothermal performance of two selected wall structures was investigated based on WUFI simulation program. The results displayed that the indoor temperature had impact on the moisture accumulation in the insulation layer for both modeled walls, showing that lower indoor temperature resulted in higher moisture accumulation, especially in the wood frame structure. Also, the yearly moisture accumulation profile exhibited a downward shift throughout the year by adding a vapour retarder with a lower sd-value. In addition, both of the two walls have condensation risk in winter, due to low temperature level. The wood frame structure has a bigger fluctuation and higher condensation risk than the concrete structure.

• Computers and Concrete
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• v.27 no.4
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• pp.369-383
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• 2021

This article deals with the frequency analysis of viscoelastic sandwich disk with graphene nano-platelets (GPLs) reinforced viscoelastic concrete (GPLRVC) face sheets and honeycomb core. The honeycomb core is made of aluminum due to its low weight and high stiffness. The rule of the mixture and modified Halpin-Tsai model are engaged to provide the effective material constant of the concrete. By employing Hamilton's principle, the governing equations of the structure are derived and solved with the aid of the Generalize Differential Quadrature Method (GDQM). In this paper, viscoelastic properties are modeled according to Kelvin-Voigt viscoelasticity. The deflection as the function of time can be solved by the fourth-order Runge-Kutta numerical method. Afterward, a parametric study is carried out to investigate the effects of the outer to inner radius ratio, hexagonal core angle, thickness to length ratio of the concrete, the weight fraction of GPLs into concrete, and the thickness of honeycomb core to inner radius ratio on the frequency of the viscoelastic sandwich disk with honeycomb core and FG-GPLRVC face sheet.

• Structural Engineering and Mechanics
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• v.56 no.5
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• pp.707-726
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• 2015

There is a growing trend of considering uncertainty in optimization process since last few decades. In this regard, Robust Design Optimization (RDO) scheme has gained increasing momentum because of its virtue of improving performance of structure by minimizing the variation of performance and ensuring necessary safety and feasibility of constraint under uncertainty. In the present study, RDO of reinforced concrete folded plate and shell structure has been carried out incorporating uncertainty in the relevant parameters by Monte Carlo Simulation. Folded plate and shell structures are among the new generation popular structures often used in aesthetically appealing constructions. However, RDO study of such important structures is observed to be scarce. The optimization problem is formulated as cost minimization problem subjected to the force and displacements constraints considering dead, live and wind load. Then, the RDO is framed by simultaneously optimizing the expected value and the variation of the performance function using weighted sum approach. The robustness in constraint is ensured by adding suitable penalty term and through a target reliability index. The RDO problem is solved by Sequential Quadratic Programming. Subsequently, the results of the RDO are compared with conventional deterministic design approach. The parametric study implies that robust designs can be achieved by sacrificing only small increment in initial cost, but at the same time, considerable quality and guarantee of the structural behaviour can be ensured by the RDO solutions.