• Title, Summary, Keyword: thermal loads

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Evaluation of Thermal and Visual Environment for the Glazing and Shading Device in an Office Building with Installed of Venetian Blind (베네시안 블라인드가 적용된 오피스 건물의 외피 투과체 계획을 위한 열·빛 환경 평가에 대한 연구)

  • Kim, Chul-Ho;Kim, Kang-Soo
    • KIEAE Journal
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    • v.15 no.6
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    • pp.101-109
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    • 2015
  • Purpose: Glazing and shading devices influence a lot on the thermal and visual environment in office buildings. Solar heat and daylight are contrary concept, therefore proper arrangement of thermal and optical performance is needed when designing a glazing and shading devices. The purpose of this study is to examine the conditions of the glazing and shading devices available for promoting the reduction of cooling loads + lighting loads and the improvement in thermal comfort and visual comfort for the summer season in an office building installed with venetian blind. Method: This study established 12 simulation cases which have different glazings and the positions of venetian blind for evaluating different thermal and optical performance. And by using EnergyPlus v8.1 and Window v7.2 program, we quantitatively analyzed cooling loads + lighting loads, thermal comfort and visual comfort in an office building installed with the glazing and shading devices. Result: Consequently, Case 9(Double Low-E+Exterior Blind) is the best arrangement of solar heat gain and daylight influx, thereby becomes the most excellent case of reducing cooling+lighting loads(46.8%) and simultaneously becomes the enhancement case in thermal comfort. Also, DGI(Daylight glare index) under clear sky conditions in summer was evaluated to be 19.6, and thereby satisfied the recommendation level of allowing visual comfort.

Estimation of Design Thermal Loads on PSC Box Girder Bridges by Statistical Extrapolation of Analytical Data (해석 데이터의 통계적 방법을 통한 PSC 박스거더교의 설계 온도 하중 추정)

  • 황의승;임창균;이영수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.497-500
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    • 2000
  • This paper describes the procedures to estimate for the design thermal loads on prestressed concrete box girder bridges on th basis of the extreme analysis of the temperature data obtained from long-term thermal analyses. Long-term thermal analyses using the environmental data for three years were conducted, and the extreme distributions of th thermal loads are then determined by the tail-equivalence method, and the thermal loads corresponding to selected return period are calculated. Finally, the results are compared to the specifications suggested in a current design code for thermal loads.

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Thermal Fatigue Test of an Annular Structure

  • Hwang Jeong-Ki;Suh Chang-Min;Kim Chae-Ho
    • Journal of Mechanical Science and Technology
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    • v.20 no.1
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    • pp.59-65
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    • 2006
  • A half-scaled large test model for the main components of the real annular structure was built and the thermal behaviors were experimented and obtained by thermal cyclic loads. The model design and the test conditions for the thermal loads were determined to take into consideration the thermal and mechanical loads acting on the real annular structure by finite element analyses. Temperature profiles and strains of the main components of the model were measured at an early stage of the test and periodically throughout the test in the given test conditions. After completion of the thermal cyclic tests, no evidence of crack initiation and propagation were identified by a dye penetration test. The measured strains at the critical parts were slightly increased proportionally with the increase in the number of the thermal cycles.

Thermoelastic dynamic analysis of wavy carbon nanotube reinforced cylinders under thermal loads

  • Moradi-Dastjerdi, Rasool;Payganeh, Gholamhassan
    • Steel and Composite Structures
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    • v.25 no.3
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    • pp.315-326
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    • 2017
  • In this work, thermoelastic dynamic behavior of functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylinders subjected to mechanical pressure loads, uniform temperature environment or thermal gradient loads is investigated by a mesh-free method. The material properties and thermal stress wave propagation of the nanocomposite cylinders are derived after solving of the transient thermal equation and obtaining of the time history of temperature field of the cylinders. The nanocomposite cylinders are made of a polymer matrix and wavy single-walled carbon nanotubes (SWCNTs). The volume fraction of carbon nanotubes (CNTs) are assumed variable along the radial direction of the axisymmetric cylinder. Also, material properties of the polymer and CNT are assumed temperature-dependent and mechanical properties of the nanocomposite are estimated by a micro mechanical model in volume fraction form. In the mesh-free analysis, moving least squares shape functions are used to approximate temperature and displacement fields in the weak form of motion equation and transient thermal equation, respectively. Also, transformation method is used to impose their essential boundary conditions. Effects of waviness, volume fraction and distribution pattern of CNT, temperature of environment and direction of thermal gradient loads are investigated on the thermoelastic dynamic behavior of FG-CNTRC cylinders.

Nonlinear finite element analysis of reinforced concrete structures subjected to transient thermal loads

  • Zhou, C.E.;Vecchio, F.J.
    • Computers and Concrete
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    • v.2 no.6
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    • pp.455-479
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    • 2005
  • This paper describes a 2D nonlinear finite element analysis (NLFEA) platform that combines heat flow analysis with realistic analysis of cracked reinforced concrete structures. The behavior models included in the structural analysis are mainly based on the Modified Compression Field Theory and the Distributed Stress Field Model. The heat flow analysis takes into account time-varying thermal loads and temperature-dependent material properties. The capability of 2D nonlinear transient thermal analysis is then implemented into a nonlinear finite element analysis program VecTor2(C) for 2D reinforced concrete membranes. Analyses of four numerical examples are performed using VecTor2, and results obtained indicate that the suggested nonlinear finite element analysis procedure is capable of modeling the complete response of a concrete structure to thermal and mechanical loads.

Evaluation of thermal comfort and cooling loads for a multistory building

  • Lykartsis, Athanasios;B-Jahromi, Ali;Mylona, Anastasia
    • Advances in Energy Research
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    • v.5 no.1
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    • pp.65-77
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    • 2017
  • The latest UK Climate Projections (UKCP09) show that mean daily temperatures will increase everywhere in the United Kingdom. This will significantly affect the thermal and energy performance of the current building stock. This study examines an institutional fully glazed building and looks into the changes in the cooling loads and thermal comfort of the occupants during the occupied hours of the non-heating period. Furthermore, it investigates the effect of relative humidity (RH) on thermal comfort. The Design Summer Year (DSY) 2003 for London Heathrow has been used as a baseline for this study and the DSY 2050s High Emissions scenario was used to examine the performance of the building under future weather conditions. Results show a 21% increase of the cooling loads between the two examined scenarios. Thermal comfort appears to be slightly improved during the months of May and September and marginally worsen during the summer months. Results of the simulation show that a relative humidity control at 40% can improve the thermal comfort for 53% of the occupied hours. A comparison of the thermal comfort performance during the hottest week of the year, shows that when the relative humidity control is applied thermal comfort performance of the 2050s is similar or better compared to the thermal comfort performance under the baseline.

Estimation of C(t)-Integral in Transient Creep Condition for Pipe with Crack Under Combined Mechanical and Thermal Stress (II) - Elastic-Plastic-Creep - (복합응력이 작용하는 균열 배관에 대한 천이 크리프 조건에서의 C(t)-적분 예측 (II) - 탄-소성-크리프 -)

  • Song, Tae-Kwang;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1065-1073
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    • 2009
  • In this paper, the estimation method of C(t)-integral for combined mechanical and thermal loads is proposed for elastic-plastic-creep material via 3-dimensional FE analyses. Plasticity induced by initial loading makes relaxation rate different from those produced elastically. Moreover, the interactions between mechanical and thermal loads make the relaxation rate different from those produced under mechanical load alone. To quantify C(t)-integral for combined mechanical and thermal loads, the simplified formula are developed by modifying redistribution time in existing work done by Ainsworth et al..

Temperature variation in steel beams subjected to thermal loads

  • Abid, Sallal R.
    • Steel and Composite Structures
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    • v.34 no.6
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    • pp.819-835
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    • 2020
  • The effects of atmospheric thermal loads on the response of structural elements that are exposed to open environments have been recognized by research works and design specifications. The main source of atmospheric heat is solar radiation, which dominates the variation of the temperature of air, earth surface and all exposed objects. The temperature distribution along the depth of steel members may differ with the geometry configuration, which means that the different-configuration steel members may suffer different thermally induced strains and stresses. In this research, an experimental steel beam was instrumented with many thermocouples in addition to other sensors. Surface temperatures, air temperature, solar radiation and wind speed measurements were recorded continuously for 21 summer days. Based on a finite element thermal analysis, which was verified using the experimental records, several parametric studies were directed to investigate the effect of the geometrical parameters of AISC standard steel sections on their thermal response. The results showed that the overall size of the beam, its depth and the thickness of its elements are of significant effect on vertical temperature distributions and temperature differences.

Effects of Vehicle Loads on Thermal Buckling Behavior of Continuous Welded Rail Tracks (장대레일 궤도의 온도좌굴 거동에 미치는 열차하중의 영향)

  • Choi, Dong Ho;Kim, Ho Bae
    • Journal of Korean Society of Steel Construction
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    • v.12 no.6
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    • pp.727-736
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    • 2000
  • The present study investigates the influences of vehicle induced loads on the thermal buckling behavior of straight and curved continuous welded rail (CWR) tracks. Quasi-static loads model is assumed to determine the uplift region, which occurs due to the vertical track deflection induced by wheel loads of vehicle. The lateral loads of vehicle induced by weight, the speed, the superelevation and curvature of track, and other dynamic vehicle track interaction, are included in the ratio of lateral to vertical vehicle load. Parametric numerical analyses are perfomed to calculate the upper and lower critical buckling temperatures of CWR tracks, and the comparison between the results of this work and the previous results without vehicle is also included.

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A study of the rail and bridge stability according to rail conditions on the bridge (교량상 레일 조건에 따른 레일 및 교량의 안전성 연구)

  • Min, Kyung-Ju;Kim, Young-Kook;Woo, Yong-Keun
    • Proceedings of the KSR Conference
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    • pp.505-515
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    • 2009
  • In railway bridges, various loads including train load, transverse load and braking force are applied to continuous CWR or semi-continuous longer rail located on non-continuous bridge superstructures. The rail-girder interaction due to thermal expansion is also very complex in railway bridges because the thermal characteristics for each of the rails and girder are quite different. Recently, the bridge retrofits for seismic loads were performed on bridges not designed for these loads. These retrofits may however have limitations with respect to rail-girder interactions because, in general these retrofits address issues related only to seismic loads. In this study of seismic evaluations for railway bridges, the load effects on the bridge rails from the road beds through the continuous rails shall be considered. Practical methods will be proposed which will increase the railway stability. For this, rail-girder interaction analyses due to train loads, temperature changes and seismic loads were performed and the results reviewed from a practical point of view.

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