• Wind and Structures
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• v.19 no.6
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• pp.603-621
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• 2014

Past high speed wind events have exposed the vulnerability of the roof systems of existing light-framed wood structures to uplift loading, contributing greatly to economic and human loss. This paper further investigates the behaviour of light-framed wood structures under the uplift loading of a realistic pressure distribution. A three-dimensional finite-element model is first developed to capture the behaviour of a recently completed full-scale experiment. After describing the components used to develop the numerical model, a comparison between the numerical prediction and experimental results in terms of the deflected shape at the roof-to-wall connections is presented to gain confidence in the numerical model. The model is then used to analyze the behaviour of the truss system under realistic and equivalent uniform pressure distributions and to perform an assessment of the use of the tributary area method to calculate the withdrawal force acting on the roof-to-wall connections.

• Journal of Korean Association for Spatial Structures
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• v.16 no.4
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• pp.83-89
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• 2016

Middle size of membrane retractable roof is under 25m span which consists of various moving systems. Trolley is the system that leads the membrane to parking place, transferring the load from the membrane to structural cable. When membrane closes roof completely, thus, structural behavior of trolley, which may contain various material with different friction coefficients, should be investigated by vertical load. Nummerical simulation of trolley prototypes, in this research, was performed by incrementation of vertical load. Consequently, this paper studied proper friction characteristics and provided the effective inner materials of trolley.

• Coupled systems mechanics
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• v.4 no.1
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• pp.19-36
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• 2015

Modelling and analysis of a brick masonry building involves uncertainties like modelling assumptions and properties of local material. Therefore, it is necessary to perform a calibration to evaluate the dynamic properties of the structure. The response of the finite element model is improved by predicting the parameter by performing linear dynamic analysis on experimental data by comparing the acceleration. Further, a nonlinear dynamic analysis was also performed comparing the roof acceleration and damage pattern of the structure obtained analytically with the test findings. The roof accelerations obtained analytically were in good agreement with experimental roof accelerations. The damage patterns observed analytically after every shock were almost similar to that of experimental observations. Damage pattern with amplification in roof acceleration exhibit the potentiality of earthquake resistant measures in brick masonry models.

• Journal of Korean Association for Spatial Structures
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• v.22 no.1
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• pp.67-73
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• 2022

Middle size of membrane retractable roof is under 25m span which consists of various moving systems. Sliding carriage is the system that leads the membrane to parking place, transferring the load from the membrane to structural cable. When membrane moves roof, thus, structural behavior of sliding carriage, which may contain various shapes with friction coefficients, should be investigated by vertical load as well as horizontal load. Nummerical simulation of sliding carriage prototypes, in this research, were performed by incrementation of vertical load and horizontal load as well. Consequently, this paper evaluated proper shapes of inner holder of Sliding carriage and evaluated the effective contact area of inner hold.

• Wind and Structures
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• v.16 no.1
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• pp.93-115
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• 2013

This paper describes a study of the influence of a dynamically flexible building structure on pressures inside and net pressures on the roof of low-rise buildings with a dominant opening. It is shown that dynamic interaction between the flexible roof and the internal pressure results in a coupled system that is similar to a two-degree-of-freedom mechanical system consisting of two mass-spring-damper systems with excitation forces acting on both the masses. Two resonant modes are present, the natural frequencies of which can readily be obtained from the model. As observed with quasi-static building flexibility, the effect of increased dynamic flexibility is to reduce the first natural frequency as well as the corresponding peak value of the admittance, the latter being the result of increased damping effects. Consequently, it is found that the internal and net roof pressure fluctuations (RMS coefficients) are also reduced with dynamic flexibility. This model has been validated from experiments conducted using a cylindrical model with a leeward end flexible diaphragm, whereby good match between predicted and measured natural frequencies, and trends in peak admittances and RMS responses with flexibility, were obtained. Furthermore, since significant differences exist between internal and net roof pressure responses obtained from the dynamic flexibility model and those obtained from the quasi-static flexibility model, it is concluded that the quasi-static flexibility assumption may not be applicable to dynamically flexible buildings. Additionally, since sensitivity analyses reveal that the responses are sensitive to both the opening loss coefficient and the roof damping ratio, careful estimates should therefore be made to these parameters first, if predictions from such models are to have significance to real buildings.

• Earthquakes and Structures
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• v.11 no.2
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• pp.265-280
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• 2016

Environmental and operational benefits of green roofs are manifolds; however, their main disadvantages are cost and weight. New technology enabled the use of plastics to reduce the weight of green roof systems to promote their installation. To maximize their potential benefits, green roofs can be installed on existing structures. This study evaluates the influence of green roofs on the seismic response of 3, 6, and 8 storey reinforced concrete ductile moment resisting frames, which were designed according to current seismic standards, however, not designed for green roofs. For each frame, three different types of roofs are considered: gravel flat roof, extensive green roof, and intensive green roof. Nonlinear dynamic time history analysis using an ensemble of twenty real earthquake records was performed to determine the inter-storey drift demand and roof drift demand for each frame. Eigenvalue analysis was also performed to determine the impact of green roofs weight on the elastic and cracked periods of the structure. Results from the analysis demonstrated that intensive and extensive green roofs do not affect the seismic performance of reinforced concrete frame structures.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.232-237
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• 2008

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This research is about the development of solar roof system with PV/T collector to apply into buildings. A test cell experiment was performed with the PVT roof installed: It found that the hot air supply from the PVT air collector contributed to increase the heating efficiency by 2 times and the electrical efficiency by about 8%.

• Journal of the Korean housing association
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• v.22 no.3
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• pp.25-33
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• 2011

Recently, concerns about conserving proper size of urban green spaces and accessibility are increasing, regarding it as a solution to diverse urban environmental problems including pollution, ecosystem deterioration, urban climate change. Artificial ground greening such as green roofs is regarded as the only alternative that can conserve green spaces which are impossible to be secured on the ground. However, green roofs are not popularized yet and levels are very low in provincial cities despite of related technology development and support systems of related agencies. Based on the background, this study tries to present a theoretical basis of methods for green roofs, conducting green roof simulations Finally, it aims to offer base data which help establish policy direction for activation of green roof technology. As a result of a simulation for verifying temperature reduction effect, it was possible to affirm effect of a plot that green roofs applied. Especially, it was revealed that a green roof method using ground covers such as mixed planting was the most effective way to reduce temperature. Based on precise analysis of the users, actual study for activation of green roofs should be developed in the future, by presenting a standard model for experiments and obtaining information about examples of green roofs on private houses.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.449-452
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• 2008

Originally developed in Scandinavia over 40 years ago, syphonic roof drainage systems have been in use in the UK since the early 1990's. Since then, many large projects have used the syphonic system to overcome installation problems which would have been difficult to solve using a traditional gravity rainwater system.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.379-382
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• 1997

This paper introduces a new vision technique for extracting roof edges of polyhedra having specularly reflecting surfaces. There have been many previous works on object recognition using edge information. But they can not be applied to specular objects since it is hard to acquire reliable camera images of specular objects. If there is a method which can extract the edges of specular objects, it is possible to apply edge-based recognition algorithms to specular objects. To acquire the reliable edge images of specular objects, scanned double pass retroreflection method is proposed, whose main physical characteristic is curvature-sensitive. This utility of the physical characteristic is motivated by the idea that roof edges can be characterized as local surfaces of high curvature. In this paper, the optical characteristics of double pass retroreflection are discussed and a series of simulation studies are performed to verify and analyze the sensor characteristics. The results from a series of simulations show the effectiveness of the proposed method.