Déformations générées dans les bétons sous l'influence des conditions climatiques

1991 ◽  
Vol 18 (6) ◽  
pp. 1088-1092 ◽  
Author(s):  
Gérard Ballivy ◽  
Brahim Benmokrane ◽  
Omar Chaallal
Keyword(s):  
Experimental Study ◽  
Relative Humidity ◽  
Strain Gauge ◽  
Environmental Conditions ◽  
Structural Integrity ◽  
Climatic Conditions ◽  
Strain Gauges ◽  
Volume Changes ◽  
Environmental Agents ◽  
Concrete Blocks

This paper presents the results of an experimental study of strains generated in concrete by variations in climatic conditions. Three 0.16 m3 concrete blocks, instrumented with vibrating wires strain gauges, were exposed to various environmental conditions (drying–wetting) during approximately 3 years and strains were measured. The study shows that concrete strains induced by environmental agents acting alone can reach levels that may jeopardize the structural integrity of concrete structures exposed to similar conditions, when the boundary conditions cannot accommodate the resulting extensive volume changes. Key words: environmental conditions, relative humidity, temperature, drying, wetting, vibrating wires strain gauge, concrete strains.

Neoseiulus baraki (Acari: Phytoseiidae) survival and walking in response to environmental stress

2019 ◽  
Vol 24 (3) ◽  
pp. 487 ◽  
Author(s):  
Vaneska Barbosa Monteiro ◽  
Girleide Vieira França ◽  
Manoel Guedes Correa Gondim Jr ◽  
Debora Barbosa Lima ◽  
Jose Wagner Silva Melo
Keyword(s):  
Relative Humidity ◽  
Environmental Stress ◽  
Survival Time ◽  
Environmental Conditions ◽  
Walking Speed ◽  
Tracking System ◽  
Climatic Conditions ◽  
Stress Factors ◽  
Neoseiulus Baraki ◽  
Increasing Temperature

Living organism is exposed to the influence of various environmental conditions. These environmental conditions can trigger stress and compromise the fitness of the organism. As living organisms, phytoseiid mites are frequently exposed to a range of environmental stressors. In the present study, we attempted to explore the responses of the Neoseiulus baraki to environmental stress factors (temperature and humidity). Initially, the effect of different temperature (18–33 °C) and relative humidity (10–95%) levels on the survivorship of unfed N. baraki females was evaluated. Next, we estimated the walking parameters (distance traveled and average walking speed) with a computerized tracking system and we tested how N. baraki is constrained in their effective displacement by their ability to walk and survive in absence of food. The proportion of surviving N. baraki as well as mean survival time decreased significantly with increasing temperature. The opposite trend was observed to relative humidity. The distance covered by N. baraki reduced with increasing temperature (when only taking the temperature dependence of the survival time but not of walking speed and neither the tortuosity of the walking path) ranged from 550 m at 18 ºC to 100 m at 33 ºC. Under climatic conditions representative for the Tropics (27 ºC and 75 % RH) N. baraki was able to survive up to 1.5 days (36 h) without feeding and covered 0.9 m in 10 min as displacement estimated by walking.

scholarly journals Aerosol jet printed capacitive strain gauge for soft structural materials

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Kiyo T. Fujimoto ◽  
Jennifer K. Watkins ◽  
Timothy Phero ◽  
Doug Litteken ◽  
Kevin Tsai ◽  
...  
Keyword(s):  
Strain Gauge ◽  
Structural Integrity ◽  
Superior Performance ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Destructive Testing ◽  
Flexible Polymer ◽  
Load Monitoring ◽  
High Elongation ◽  
Aerosol Jet Printing

AbstractSoft structural textiles, or softgoods, are used within the space industry for inflatable habitats, parachutes and decelerator systems. Evaluating the safety and structural integrity of these systems occurs through structural health monitoring systems (SHM), which integrate non-invasive/non-destructive testing methods to detect, diagnose, and locate damage. Strain/load monitoring of these systems is limited while utilizing traditional strain gauges as these gauges are typically stiff, operate at low temperatures, and fail when subjected to high strain that is a result of high loading classifying them as unsuitable for SHM of soft structural textiles. For this work, a capacitance based strain gauge (CSG) was fabricated via aerosol jet printing (AJP) using silver nanoparticle ink on a flexible polymer substrate. Printed strain gauges were then compared to a commercially available high elongation resistance-based strain gauge (HE-RSG) for their ability to monitor strained Kevlar straps having a 26.7 kN (6 klbf) load. Dynamic, static and cyclic loads were used to characterize both types of strain monitoring devices. Printed CSGs demonstrated superior performance for high elongation strain measurements when compared to commonly used HE-RSGs, and were observed to operate with a gauge factor of 5.2 when the electrode arrangement was perpendicular to the direction of strain.

scholarly journals Effect of Extreme Climate on Topology of Railway Prestressed Concrete Sleepers

Climate ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 17 ◽  
Author(s):  
Dan Li ◽  
Sakdirat Kaewunruen
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Prestressed Concrete ◽  
Vital Role ◽  
Climatic Conditions ◽  
Time Dependent ◽  
Railway Infrastructure ◽  
Time Dependent Behaviour ◽  
The Impact ◽  
Dependent Behaviour

Railway networks are exposed to various environmental conditions. It is thus critical that infrastructure components can tolerate such effects by design. Railway sleepers are a critical safety component in ballasted track systems. Prestressed concrete is currently the most common material for railway sleepers due to its superior advantages in structural performance, low maintenance, sustainability, and construction. In practice, many prestressed concrete sleepers are installed in harsh environments that are subject to various changes in climate. Environmental conditions are, therefore, one of the most critical phenomena affecting the time-dependent behaviour of prestressed concrete sleepers. Hence, the impact of climate changes on the serviceability of railway infrastructure needs to be thoroughly investigated. Temperature and relative humidity are crucial aspects that have not been sufficiently studied so far with reference to prestressed concrete sleepers embedded in track systems. This study aims to investigate the effects of extreme climatic conditions on the performance and time-dependent behaviour of prestressed concrete sleepers using contemporary design approaches. The issue concerning the effects of climate uncertainties on creep and shrinkage is rigorously investigated on the basis of both environmental temperature and relative humidity. The outcome indicates that environmental conditions play a vital role in the time-dependent behaviour of prestressed concrete sleepers. The insights will be essential for assessing the long-term serviceability of prestressed concrete sleepers that have been installed in railway lines and are subjected to extreme environmental conditions.

scholarly journals A Study on the Carbonation Rate of Concrete Exposed in Different Climatic Conditions

2021 ◽  
pp. 128-136
Keyword(s):  
Fly Ash ◽  
Relative Humidity ◽  
Environmental Conditions ◽  
Climatic Conditions ◽  
Climate Conditions ◽  
Industrial Areas ◽  
Carbonation Process ◽  
Carbonation Resistance ◽  
Proper Design ◽  
One Year

Recently, the degradation of concrete has become a serious problem worldwide and one of the principle factors of degradation is the carbonation process. It is well established that environmental conditions affect the carbonation progress of concrete among the most important factors that can greatly affect the carbonation resistance of concrete are relative humidity (RH) and temperature. Carbonation has become a threat to concrete structures, especially in urban and industrial areas. Thus, it is necessary to have a proper design to maintain the structure's stability against degradation caused by carbonation. Therefore, this study was conducted to evaluate the effects of different environmental and climatic conditions on the carbonation rate of concrete. The specimens were prepared using OPC and fly ash (FA). After 28 days of air curing, specimens were exposed to different climate conditions under sheltered and un-sheltered conditions. The carbonation tests were conducted at the ages of 6 and 12 months. It was found that the carbonation rates were significantly influenced by the climate and environmental conditions; the specimens exposed to a relatively dry environment and low annual precipitations have shown higher carbonation during one-year exposure. Moreover, in unsheltered conditions, the annual precipitation significantly affects the carbonation rate of concrete. Furthermore, it was observed that a 20% replacement of FA does not enhance the carbonation resistance of concrete.

scholarly journals Effect of Environmental Conditions on Performance of Corrugated Sheet Boxes Manufacturing Process

2019 ◽  
Vol 8 (2S7) ◽  
pp. 339-343
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Environmental Conditions ◽  
Performance Test ◽  
Mechanical Performance ◽  
Sheet Material ◽  
Climatic Conditions ◽  
Atmospheric Conditions ◽  
Severe Condition ◽  
Moisture Content Level

Corrugated sheet material is very sensitive to the environmental conditions, especially moisture. The present study focuses on the mechanical behavior of corrugated sheet box board at different humidity and temperature conditions. The objective of this study is to study the important properties of corrugated sheet boxes at different climatic conditions and also to study the influence of the properties of corrugated sheet paper on the properties of corrugated board and box at various environmental conditions. The mechanical performance test carried out under controlled atmospheric conditions where the temperature (0C) range was studied from 200C to 500C and the relative humidity (Rh) range was studied from dry condition 30% Rh to severe condition 90% Rh. The results tested showed that the maximum compressive load of empty corrugated sheet box sealed exposed to moisture content decreased with the increase of temperature and relative humidity. In general it is observed in paper, corrugated sheet board and boxes that have optimum combined properties are obtained at moisture content level at 7-8% and hence moisture content of 7-8% may be the ideal value for corrugated sheet paper used in corrugated packaging industry

scholarly journals Microclimate Conditions in Rooms: Their Impact on Mold Development in Buildings

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4492 ◽  
Author(s):  
Bożena Orlik-Kożdoń
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Climatic Conditions ◽  
In Situ Studies ◽  
Thermal Bridges ◽  
Microclimate Conditions

The publication concerns the problem of adopting proper environmental conditions in the assessment of mold development in the so-called thermal bridges in the form of corners. The paper discusses the factors determining the development of mold and the models that predict its growth. The conditions of the internal microclimate, which is used in hygrothermal diagnostics of walls, were also recalled. Thermal bridges are areas where mold development takes place, therefore the climatic conditions in the room taken for their assessment—As it is currently applied—Are considered inappropriate. This thesis is confirmed by the results of in situ studies of changes in temperature and relative humidity in the area of corners. Some of these findings are presented in the work. On their basis, the author introduces the concept of the so-called geometric climate that would take into account the change of these parameters within thermal bridges of the corner type.

Experimental study of an earth to air heat exchanger (EAHE) for warm humid climatic conditions

Geothermics ◽  
2020 ◽  
Vol 84 ◽  
pp. 101741 ◽  
Author(s):  
H.P. Díaz-Hernández ◽  
E.V. Macias-Melo ◽  
K.M. Aguilar-Castro ◽  
I. Hernández-Pérez ◽  
J. Xamán ◽  
...  
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Climatic Conditions

Current Design Rules for Welding of Wind Energy Structures for Arctic Conditions

2019 ◽  
Vol 822 ◽  
pp. 452-458
Author(s):  
Sergey Lopaev ◽  
Pavel Layus ◽  
Paul Kah ◽  
Sergey Parshin
Keyword(s):  
Wind Energy ◽  
Structural Integrity ◽  
Structural Characteristics ◽  
Welding Process ◽  
Climatic Conditions ◽  
Welding Parameters ◽  
Reliable Operation ◽  
Arctic Conditions ◽  
Current Design ◽  
Standards And Guidelines

An article presents a review of current standards and guidelines in the field welding fabrication requirements for wind energy structures in arctic conditions. Extreme climatic conditions, such as Arctic, have a strong influence on the requirements for wind turbines structural characteristics, materials and fabrication methods. Special attention has to be paid for selecting steels with suitable mechanical properties, processing methods and delivery conditions. Additionally, it is highly important to select proper welding process and welding parameters, so that the structural integrity and reliable operation can be achieved.

Experimental Study on Hygroscopicity of Rapeseed (Brassica Napus)

2012 ◽  
Vol 479-481 ◽  
pp. 2275-2278
Author(s):  
Ming Jin Yang ◽  
Wu Ming Xu ◽  
Tian Tang ◽  
Ling Yang ◽  
Feng Liu
Keyword(s):  
Experimental Study ◽  
Brassica Napus ◽  
Relative Humidity ◽  
Moisture Absorption ◽  
Early Period ◽  
Critical Relative Humidity ◽  
Temperature And Humidity ◽  
Higher Temperature

The hygroscopicity property of the rapeseed at different temperature and humidity was experimental studied in this paper. Tested results show that: the moisture absorption rates increase with the increase of relative humidity at the early period of absorption, and higher temperature leads to earlier reach of moisture equilibrium; the critical relative humidity(CRH) increases with the increase of temperature; the optional relative humidity for safety storage of rapeseed should be controlled less than 60%.

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