scholarly journals Hygro-thermal analysis of a flat roof structure integrating a variable vapor-diffusivity membrane

2021 ◽  
Author(s):  
Riccardo Pinotti ◽  
Paola Brugnara ◽  
Stefano Avesani
Keyword(s):  
Thermal Analysis ◽  
Roof Structure ◽  
Flat Roof

Rainwater Ponding on Roof Structures with Interaction between Main Girders and Purlins

2019 ◽  
Author(s):  
H. H. (Bert) Snijder ◽  
S. N. M. (Simon) Wijte
Keyword(s):  
Design Method ◽  
Rain Intensity ◽  
Roof Structure ◽  
Iterative Calculation ◽  
Linear Behavior ◽  
Flat Steel ◽  
Design Calculations ◽  
Flat Roof ◽  
Near Future ◽  
Flat Roofs

<p>Rainwater causes flat roofs to deflect resulting in ponding. Due to the deflection, extra rainwater flows to the lower area of the roof, resulting in a larger loading with a larger deflection, resulting in more rainwater flowing towards this area, etc. Failure of flat roof structures due to ponding under heavy rainfall frequently happens in The Netherlands with an average of 15 incidents each year in the last decades. An increase in rain intensity due to climate change is expected to increase these numbers in the near future. Nevertheless, ponding on light roof structures is still underestimated as a significant load case in design. Moreover, the design calculations necessary are complex due to geometrical non-linear behavior. A number of software programs are available, but to keep insight in the process of rainwater ponding, a simple analytical design method for ponding of flat (steel) roof structures was developed including the interaction between main girders and purlins. The paper presents this method which avoids an iterative calculation procedure. Subsequently, this method is used to analyze a roof structure concluding that the interaction between main girders and purlins cannot be neglected.</p>

The Structure Design and Analysis of Predigest Laser Combine Bind and Extend Bind Flat Roof

2011 ◽  
Vol 291-294 ◽  
pp. 2466-2470
Author(s):  
Xu Dong Han ◽  
Bing Wang ◽  
Kui Shi ◽  
Chang Shun Liu ◽  
Heng Kun Wang ◽  
...  
Keyword(s):  
High Precision ◽  
Structure Design ◽  
Small Space ◽  
Roof System ◽  
Roof Structure ◽  
Flat Roof

This paper put forward a kind of predigest laser combine bind and extend bind flat roof structure, which is founded as fission flat roof, and can be built in an little room 1280mm×990mm×815mm. This flat roof space location can be adjusted. This kind of seat can ensure the system complete laser combine and close as high precision. In this paper we designed the laser combine and close whole structure and install design. At last we did some finite statics analysis to some important parts. This design can ensure every laser fire directional adjust mete lower ±30′, and the flat roof quality is 770kg. The transition benchmark flat roof system most meet and emergency is 0.005mm at the premise of bear the weight of turn flat laden. It can be seen that this structure can satisfy the request of many lasers small space laser extend bind and adjust. This kind can be extended to other light combine bind and extend bind structure design.

On Some Aspects of Application of Vegetative Roofs in Building Structures

2014 ◽  
Vol 897 ◽  
pp. 329-332
Author(s):  
Michal Majsniar ◽  
Stanislav Šťastník
Keyword(s):  
Thermal Analysis ◽  
Building Structures ◽  
Roof Structure

The paper shows the possibilities of the arrangement of particular layers of vegatative roofs for building structures and the influence of soil on the distribution of temperature in a roof structure, using the software based on the non-stationary thermal analysis.

scholarly journals Thermal Technical Analysis of Lightweight Timber-Based External Wall Structures with Ventilated Air Gap

2021 ◽  
Vol 13 (1) ◽  
pp. 378
Author(s):  
Denisa Valachova ◽  
Andrea Badurova ◽  
Iveta Skotnicova
Keyword(s):  
Thermal Analysis ◽  
Theoretical Data ◽  
Energy Performance ◽  
Heat Emission ◽  
Air Gap ◽  
Cold Night ◽  
External Wall ◽  
Roof Structure ◽  
Wall Structures ◽  
Ventilated Facade

Lightweight timber-based structures are an increasingly common part of envelopes of new buildings due to increasing requirements for their energy performance. In addition, due to the fact that wood is a sustainable material, it can be assumed that the share of these structures in civil engineering will continue to increase. The subject of this article is the thermal analysis of timber-based lightweight structures under winter conditions to expand information about thermal processes in these structures. This article deals with the lightweight timber-based external wall structures with a ventilated facade and a double-skin roof structure. Experimental temperature measurements inside the structures and ventilated air gaps are used to perform the thermal analysis. By comparing experimental and theoretical data obtained by performing numerical simulation, it was shown that for achieving an ideal match of numerical simulations and measured physical properties it is necessary to take into account not only external temperatures affecting these structures, but also other factors such as solar radiation and heat emission into the cold night sky. In the case of the external walls with ventilated facade, the benefit of a ventilated air gap has been demonstrated in relation to smaller temperature fluctuations that affect the structures.

Analysis of Structure and Thermal Performance of Roof with Reinforced Concrete Prefabricated Corrugated Board

2012 ◽  
Vol 161 ◽  
pp. 236-241
Author(s):  
Li Li ◽  
Xian Chen Bai ◽  
Ji Ping Guo
Keyword(s):  
Reinforced Concrete ◽  
Thermal Performance ◽  
Level Structure ◽  
Corrugated Board ◽  
Roof Structure ◽  
New Countryside Construction ◽  
New Countryside ◽  
Flat Roof ◽  
Basic Level

This article aims at solving the problems of waterproof layer aging, hollowing, deformation and cracks and other major issues in the process of use of the traditional flat roof. On the basis of using traditional materials on the flat roof, basic-level structure of the roof is designed into reinforced concrete prefabricated corrugated board. Through the analysis of its structure and the thermal performance, this article attempts to explore the adaptability, and the promotion of reinforced concrete pre-cast groove board flat roof structure technology in the new countryside construction.

scholarly journals Surface temperature of bitumen sheets in the flat roof structure

2019 ◽  
Vol 279 ◽  
pp. 02017 ◽  
Author(s):  
Jan Plachý ◽  
Jana Vysoká
Keyword(s):  
Surface Temperature ◽  
Experimental Measurement ◽  
High Surface ◽  
Roof Structure ◽  
Temperature Problem ◽  
Warm Summer ◽  
Surface Measurements ◽  
High Surface Temperature ◽  
Flat Roof ◽  
Flat Roofs

This paper deals with the surface temperature problem of flat roofs, where bitumen sheets are used as the final waterproofing layer. Currently it is possible to find defects due to the high surface temperature of the waterproofing layer on flat roofs. The result of such a high surface temperature is, for example, the release of bitumen sheets and the sublimation of the thermal insulation from foamed polystyrene. The paper focuses on the influence of the type, the color of the sprinkling and the type of background on the surface temperature. The aim of this paper is to determine the surface temperature of bitumen sheets based on the experimental measurement depending on the type and the colour of the surface. Measurements were made during warm summer days. Samples of bitumen sheets with green, grey, blue-grey, red, white and black-grey sprinkling were used. Concrete and foamed polystyrene were used as a background under bitumen sheets.

A Study on the Fluctuating Pressure Correlation of a Cantilevered Elliptic Annular Roof Structure

2016 ◽  
Vol 16 (01) ◽  
pp. 1640013
Author(s):  
Zhaohui Chen ◽  
Yi Sun ◽  
Haiyong Zhang ◽  
Zhaohui Zhang
Keyword(s):  
Coherence Function ◽  
Wind Tunnel Test ◽  
Fluctuating Pressure ◽  
Large Span ◽  
High Rise ◽  
Roof Structure ◽  
Inflow Turbulence ◽  
Rigid Model ◽  
Wind Pressures ◽  
Flat Roof

A wind tunnel test on a large-span cantilevered elliptical annular roof was carried out. The time series of wind pressures were tested simultaneously on the upper and lower surfaces of a roof structure rigid model, that was exposed to open and suburban boundary layer air flows in various wind directions. The spatial correlation characteristics of fluctuating pressures on the roof structure were analyzed. Both the analyzing results of the correlation coefficient in time domain and the coherence function in frequency domain indicated that the correlation structure of the fluctuating pressure of a large-span roof is sensitive to the location of the investigated taps, the roof geometry, the wind direction, and the inflow turbulence. Therefore, the simulation methodology, using a single coherence function, based on the spatial interval of two taps, ignoring the geometry characteristics and the particular tap locations on the roof, a method commonly used in wind load simulations for high-rise and flat roof structures, is shown to not be appropriate for large-span cantilevered roof structures. This quasi-steady approach cannot be employed to evaluate large-span roof structures.

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