• Wind and Structures
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• 제23권6호
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• pp.523-542
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• 2016

Snowdrift formation on roofs should be considered in snowy and windy areas to ensure the safety of buildings. Presently, the prediction of snowdrifts on roofs relies heavily on field measurements, wind tunnel tests and numerical simulations. In this paper, a new snowdrift modeling method by using CFD (Computational Fluid Dynamics) coupled with DEM (Discrete Element Method) is presented, including material parameters and particle size, collision parameters, particle numbers and input modes, boundary conditions of CFD, simulation time and inlet velocity, and coupling calculation process. Not only is the two-way coupling between wind and snow particles which includes the transient changes in snow surface topography, but also the cohesion and collision between snow particles are taken into account. The numerical method is applied to simulate the snowdrift on a typical stepped flat roof. The feasibility of using coupled CFD with DEM to study snowdrift is verified by comparing the simulation results with field measurement results on the snow depth distribution of the lower roof.

• Wind and Structures
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• 제5권6호
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• pp.493-514
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• 2002

Seven hip roof building models for $10^{\circ}$, $15^{\circ}$, $20^{\circ}$, $25^{\circ}$, $30^{\circ}$, $35^{\circ}$ and $40^{\circ}$ roof pitch with large overhangs of 1.1 m were tested in a wind tunnel at the university of Roorkee, India to investigate wind pressure distributions over hip roofs for various roof pitch and wind direction. The results show that the roof pitch and wind direction do significantly affect the magnitude and distribution of the roof pressures. The $40^{\circ}$ roof pitch has been found to experience the highest peak suctions at the roof corners amongst the seven hip roofs tested. Pressures on $15^{\circ}$, $20^{\circ}$ and $30^{\circ}$ hip roofs are comparable with those reported by Xu and Reardon (1998). Meecham et al. (1991) for $18.4^{\circ}$ hip roof is compatible with $15^{\circ}$ hip roof of the present study. Holmes's works (1994) on gable roof have also been compared with the present work. Zoning for codification has also been attempted since IS875 (Part-3) does not include this information. A comparison for design value has also been made with BRE Report No. 346.

• Structural Engineering and Mechanics
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• 제63권2호
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• pp.195-206
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• 2017

This paper presents the parametric numerical analysis on the ultimate bearing capacity of the purlin-sheet roofs connected by standing seam clips. The effects of several factors on failure modes and ultimate bearing capacity of the purlins are studied, including setup of anti-sag bar, purlin type, sheet thickness and connection type et al. A simplified design formula is proposed for predicting the ultimate bearing capacity of purlins. Results show that setting the anti-sag bars can improve the ultimate bearing capacity and change the failure modes of C purlins significantly. The failure modes and ultimate bearing capacity of C purlins are significantly different from those of Z purlins, in the purlin-sheet roof connected by standing seam clips. Setting the anti-sag bars near the lower flange is more favorable for increasing the ultimate bearing capacity of purlins. The ultimate bearing capacity of C purlins increases slightly with sheet thickness increasing from 0.6 mm to 0.8 mm. The ultimate bearing capacity of the purlin-sheet roofs connected by standing seam clips is always higher than those by self-drilling screws. The predictions of the proposed design formulas are relatively in good agreement with those of EN 1993-1-3: 2006, compared with GB 50018-2002.

• 환경영향평가
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• 제19권6호
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• pp.591-605
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• 2010

Cool roofs are currently being emerged as one of important mechanism to save energy in relation to the building. This paper reviews worldwide experiences (USA, Japan and EU etc) for the potential benefits cool roofs offer in relation to building energy saving for comparison purposes. It is confirmed that there is a significant potential to the energy saving by introducing the cool roof in a Korean climate because of similarity in terms of HDD (Heating Degree Day) and CDD (Cooling Degree Day) as those countries reviewed. Such a comparative study highlights that the type of measurements performed and the quantitative parameters reported from the countries should be standardized in Korean context in order to implement further comparable experiments for scientifically sound investigations. It is anticipated that this research output could be used as a valuable reference in implementing a Nation-wide cool roofing strategy in the central and local governments since a suitable technical, more objective direction has been proposed based on the measured, fully quantitative performance of the involved components of a cool roof system in the global context. From this critical review, a very important step has been made concerning the practicality of cool roof in Korean context. Ultimately, the suggestion in this paper will greatly contribute to opening new possibilities for introducing cool roof in this country, proposed as an initial aim of this paper.

• 한국물환경학회지
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• 제27권3호
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• pp.300-305
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• 2011

This study aimed at analyzing the runoff quality by the layer thickness and material of soil roof to make best use of the rainwater falling on it in terms of safety and efficiency and resulted in the following assessments. It turned out that the concentrations decreased more in T-N, $NO_3$-N, $NH_4$-N, T-P and $PO_4$-P in roof rainwater except 30 cm for the RW1 soil roof after passing through it than those of first rainwater. On the other hand, the concentrations in rainwater passing through gravel roof turned out to be equal or same to those of the first rainwater. As a result of analysis of metallic stuff in runoff, there was no indication of Cd, Cr, Mn and Pb as well. The concentration of Cu, Fe and Zn in rainwater through soil roof became less than that of the first rainwater. In this research, the soil roof showed the good efficiency in lowering the concentration of such components as nitrogen, phosphorus and metals. Based on the results from this work, more practical study would be required further in the future in relation to soil roof when installing the rainwater-utilizing facilities.

• 국제초고층학회논문집
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• 제11권4호
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• pp.287-300
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• 2022

Unconventional structures are getting more popular in recent days. Large-span roofs are used for many structures, such as airports, stadiums, and conventional halls. Identifying the pressure distribution and wind load acting on those structures is essential. This paper offers a collaborative study of computational fluid dynamics (CFD) simulations and wind tunnel tests for assessing wind pressure distribution for a building with a combined slender curved roof. The hybrid turbulence model, Improved Delayed Detached Eddy Simulation (IDDES), simulates the open terrain turbulent flow field. The wind-induced local pressure coefficients on complex roof structures and the turbulent flow field around the structure were thus calculated based upon open terrain wind flow simulated with the FLUENT software. Local pressure measurements were investigated in a boundary layer wind tunnel simultaneous to the simulation to determine the pressure coefficient distributions. The results predicted by CFD were found to be consistent with the wind tunnel test results. The comparative study validated that the recommended IDDES model and the vortex method associated with CFD simulation are suitable tools for structural engineers to evaluate wind effects on long-span complex roofs and plan irregular buildings during the design stage.

• Wind and Structures
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• 제6권2호
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• pp.141-150
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• 2003

This paper presents galloping analysis of multiple-degree-of-freedom (MDOF) structural roofs with multiple orientations. Instead of using drag and lift coefficients and/or their combined coefficient in traditional galloping analysis for slender structures, this study uses wind pressure coefficients for wind force representation on each and every different orientation roof, facilitating the galloping analysis of multiple-orientation roof structures. In the study, influences of nonlinear aerodynamic forces are considered. An energy-based equivalent technique, together with the modal analysis, is used to solve the nonlinear MDOF vibration equations. The critical wind speed for galloping of roof structures is derived, which is then applied to galloping analysis of roofs of a stadium and a high-rise building in China. With the aid of various experimental results obtained in pertinent research, this study also shows that consideration of nonlinear aerodynamic forces in galloping analysis generally increases the critical wind speed, thus enhancing aerodynamic stability of structures.

• 한국주거학회논문집
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• 제13권5호
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• pp.43-50
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• 2002

The purpose of this study is to find the types and symbolic meanings of the pattern shown in the Korean traditional houses. The major findings were as follows, 1) The patterns shown in the Korean traditional houses are classified into the types of the animal, plant, good-luck geometry according to the Motifes 2) The patterns of the Korean traditional houses were expressed in the fences, gates, chimneies, walls, windows and doors, railings, roofs. 3) Korean traditional patterns are expressed the meanings of the protection, long life, good-luck, good meaning, decoration in the fences, gates, chimneies, walls, windows and doors, railings, roofs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.168-171
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• 2006

The Korean Solar Thermal Industry hopes to realize 1 Million Solar Thermal Roofs. According to the 2nd Renewable Basic Plan : 2003-2012 the Government showed a very aggressive Solar Thermal Deployment Plan including Solar Thermal Apartment Housings Program. Owing to the Vision Statement such as Million Solar Thermal Roofs Program Korean Solar thermal Industry also can bring another shinny days Especially the more solar thermal applications such as to the Apartment Housings and Green Villages could bring a sustainable Solar Society Korea The RPA Program by the 9 Major Non-Private Energy Corporal ions and the RPS Program for the Solar Thermal Energy shall be another useful policy for the realization of Million Solar Korea era.

• Wind and Structures
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• 제30권3호
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• pp.299-316
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• 2020

Based on wind tunnel tests, this paper investigates the aerodynamic behavior of a large span canopy roof with elliptical plan and hyperbolic paraboloid shape. The statistics of pressure coefficients and the peak factor distributions are calculated for the top and bottom faces of the roof, and the Gaussian or non-Gaussian characteristics of the pressure time-histories in different areas of the roof are discussed. The cross-correlation of pressures at different positions on the roof, and between the top and bottom faces is also investigated. Combination factors are also evaluated to take into account the extreme values of net loads, relevant to the structural design of canopies.