A new recommended load cycle for dynamic wind-resistant test of roof system based on the principle of damage equivalence

2021 ◽  
pp. 103911
Author(s):  
Tao Wu ◽  
Ying Sun ◽  
Zhenggang Cao ◽  
Yang Chen
Keyword(s):  
Load Cycle ◽  
Roof System

scholarly journals Dynamics of the Ice-Crushing Process

1988 ◽  
Vol 34 (118) ◽  
pp. 318-326 ◽  
Author(s):  
Ian J. Jordaan ◽  
Garry W. Timco
Keyword(s):  
Ice Sheet ◽  
Load Cycle ◽  
Stored Energy ◽  
Indentation Process ◽  
Ice Particles ◽  
Mode Of Failure ◽  
Indentation Tests ◽  
Energy Exchanges ◽  
The Mean ◽  
Crushed Ice

Abstract During fast indentation tests on ice sheets at constant rates, crushing is commonly observed at appropriate combinations of speed and aspect ratio. An analysis is made of this mode of failure, using as a basis a recently conducted test on an ice sheet under controlled conditions. The variation of load with time is given special attention, and cyclic variation of load is associated with periodic crushing (pulverization) events, followed by clearing of the crushed ice particles. An analysis of the clearing process is summarized in the paper, treating the crushed ice as a viscous material. A detailed analysis of the energy exchanges during the indentation process is given. Elastic variations of stored energy in the indenter and in the ice sheet are calculated; these are relatively minor. The dissipation of energy during a typical load cycle (3 mm movement during 0.05 s) is about 8 J. The energy required to create surfaces of the crushed ice particles is small (0.006 J), as is the work of crushing based on mechanical testing (0.09 J). It is concluded that the process of viscous extrusion of crushed ice is the main seat of energy dissipation, basically as a frictional process. A relationship for the mean thickness of the crushed ice layer is developed, based on energy-balance considerations.

The Simulated Impact of Climate on the Drying Times of a Wetted Low-Slope Roof System

1993 ◽  
Vol 16 (3) ◽  
pp. 234-245
Author(s):  
A.O. Desjarlais ◽  
D.M. Kyle ◽  
J.E. Christian
Keyword(s):  
Roof System

scholarly journals Heat Transfer Measurement within Green Roof with Incinerated Municipal Solid Waste Aggregates

2021 ◽  
Vol 13 (13) ◽  
pp. 7115
Author(s):  
Mostafa Kazemi ◽  
Luc Courard ◽  
Julien Hubert
Keyword(s):  
Heat Transfer ◽  
Heat Resistance ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Green Roof ◽  
Insulation Material ◽  
Drainage Layer ◽  
Roof System ◽  
Substrate Layer ◽  
Significant Difference

A green roof is composed of a substrate and drainage layers which are fixed on insulation material and roof structure. The global heat resistance (Rc) within a green roof is affected by the humidity content of the substrate layer in which the coarse recycled materials can be used. Moreover, the utilization of recycled coarse aggregates such as incinerated municipal solid waste aggregate (IMSWA) for the drainage layer would be a promising solution, increasing the recycling of secondary resources and saving natural resources. Therefore, this paper aims to investigate the heat transfer across green roof systems with a drainage layer of IMSWA and a substrate layer including recycled tiles and bricks in wet and dry states according to ISO-conversion method. Based on the results, water easily flows through the IMSWAs with a size of 7 mm. Meanwhile, the Rc-value of the green roof system with the dry substrate (1.26 m2 K/W) was 1.7 times more than that of the green roof system with the unsaturated substrate (0.735 m2 K/W). This means that the presence of air-spaces in the dry substrate provided more heat resistance, positively contributing to heat transfer decrease, which is also dependent on the drainage effect of IMSWA. In addition, the Rc-value of the dry substrate layer was about twice that of IMSWA as the drainage layer. No significant difference was observed between the Rc-values of the unsaturated substrate layer and the IMSWA layer.

The Algorithm for Graphic Method of Rain-Flow Counting in Programming

2011 ◽  
Vol 225-226 ◽  
pp. 1157-1161 ◽  
Author(s):  
Qing Deng ◽  
Hong Jie Yuan
Keyword(s):  
Computer Program ◽  
Execution Time ◽  
Counting Process ◽  
Load Cycle ◽  
Mean Value ◽  
Graphic Method ◽  
Counting Method ◽  
Starting Point ◽  
Mechanical Basis

In this article, a new algorithm for rain-flow counting method in computer program is introduced. In the whole counting process, this algorithm entirely follows the principle of graphic method of rain-flow counting method, and so it can embodies the mechanical basis of extracting load cycle in rain-flow counting method; during the processing of counting, the information of every load cycle can be accurately recorded, such as starting and ending time, the time of peak or valley, the value of starting point and peak (or valley), mean value and amplitude. Besides, the counting result is in full accordance with the result from graphic method. Compared to four peak-valley method, this algorithm has shorter execution time and higher efficiency.

On the green roof system. Selection, state of the art and energy potential investigation of a system installed in an office building in Athens, Greece

2008 ◽  
Vol 33 (1) ◽  
pp. 173-177 ◽  
Author(s):  
A. Spala ◽  
H.S. Bagiorgas ◽  
M.N. Assimakopoulos ◽  
J. Kalavrouziotis ◽  
D. Matthopoulos ◽  
...  
Keyword(s):  
State Of The Art ◽  
Green Roof ◽  
Office Building ◽  
Energy Potential ◽  
Roof System ◽  
System Selection

Fatigue Life Recovery via Laser Shock Peening in Mechanically Damaged Aluminium Sheet; Experiments and Prediction Models

2014 ◽  
Vol 891-892 ◽  
pp. 980-985 ◽  
Author(s):  
Niall Smyth ◽  
Philip E. Irving
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Prediction Models ◽  
Load Cycle ◽  
Laser Shock Peening ◽  
Stress Fields ◽  
Hole Drilling ◽  
Laser Shock ◽  
Aluminium Sheet ◽  
Shock Peening

This paper reports the effectiveness of residual stress fields induced by laser shock peening (LSP) to recover pristine fatigue life. Scratches 50 and 150 μm deep with 5 μm root radii were introduced into samples of 2024-T351 aluminium sheet 2 mm thick using a diamond tipped tool. LSP was applied along the scratch in a band 5 mm wide. Residual stress fields induced were measured using incremental hole drilling. Compressive residual stress at the surface was-78 MPa increasing to-204 MPa at a depth of 220 μm. Fatigue tests were performed on peened, unpeened, pristine and scribed samples. Scratches reduced fatigue lives by factors up to 22 and LSP restored 74% of pristine life. Unpeened samples fractured at the scratches however peened samples did not fracture at the scratches but instead on the untreated rear face of the samples. Crack initiation still occurred at the root of the scribes on or close to the first load cycle in both peened and unpeened samples. In peened samples the crack at the root of the scribe did not progress to failure, suggesting that residual stress did not affect initiation behaviour but instead FCGR. A residual stress model is presented to predict crack behaviour in peened samples.

Theoretical and experimental analysis of the thermal behaviour of a green roof system installed in two residential buildings in Athens, Greece

2009 ◽  
Vol 33 (12) ◽  
pp. 1059-1069 ◽  
Author(s):  
Aikaterini Sfakianaki ◽  
Elli Pagalou ◽  
Konstantinos Pavlou ◽  
Mat Santamouris ◽  
M. N. Assimakopoulos
Keyword(s):  
Thermal Behaviour ◽  
Experimental Analysis ◽  
Residential Buildings ◽  
Green Roof ◽  
Roof System
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