Temporal analysis of the performance of an elevated concrete tank considering the corrosion of the steel reinforcement

Reinforced concrete water storage tanks are civil engineering structures subject to very aggressive atmospheric conditions that expose them to harmful corrosion risk. This dangerous phenomenon caused by the penetration of chloride ions causes pitting corrosion and leads to the reduction of the section of the reinforcements and consequently to the loss of strength and the structure performance. In this study, we are interested in analyzing the performance of an elevated storage tank, taking into account the corrosion of the reinforcements subjected to tensile stress, by considering environments with different rates of aggressiveness. A method based on Housner's model is used to evaluate the tension stresses in the reinforced concrete (RC) pedestal (supporting system) of the tank, subjected to the seismic actions. A pitting corrosion model is developed in order to determine the evolution in time of the reinforcements section in different environments. Several parameters influencing corrosion are taken into account, such as concrete cover and the concentration of chlorides ions

Development of an Integrated Model to Assess the Impact of Agricultural Practices and Land Use on Agricultural Production in Morocco under Climate Stress over the Next Twenty Years

peer reviewedClimate change is one of the major risks facing developing countries in Africa for which agriculture is a predominant part in the economy. Alterations in rainfall patterns and increasing temperatures projected by the Intergovernmental Panel on Climate Change (IPCC) could lead to a decline in agricultural production in many areas requiring significant changes in agricultural practices and land distribution. The study provided estimates of the economic impacts of climate change, compared these with historical impacts of drought spells, and estimated the extent to which the current Moroccan agricultural development and investment strategy, the Plan Maroc Vert, helps in agricultural adaptation to climate change and uncertainty. The aim of this study was to quantify the effects of climate change on the overall economy by using an integrated framework incorporating a computable general equilibrium model. A concomitant factor to climate change will be the increase in population and its distribution and level of consumption, which will also influence agricultural production strategies, the conversion of agricultural land, the type of irrigation, and technological development. We demonstrated how changes in cereal production and area, affluence, and climate (rainfall and temperature) can be acquired for 12 regions of Morocco and used to develop and validate an earth system model in relation to the environment and socio-economic level, which projects their impact on current and potential land use over the next 20 years. We used different mathematical equations based on cereal area and production, population, consumption (kg/person), and change in climate (temperature and rainfall) in bour and irrigated areas for the growing season of 2014 in 12 regions to project agricultural land use over the next 20 years. Therefore, several possible scenarios were investigated to explore how variations in climate change, socio-economic level, and technological development will affect the future of agricultural land use over the next 20 years, which in turn could have important implications for human well-being. Among the 12 Moroccan regions, only 4 had a surplus of cereal production compared to their local consumption. The increase in population will generate a cereal deficit in 2024 and 2034, thus lowering the average annual quantity available per capita of cereals from 204.75 to 160.61 kg/p in 2014 and 2034, respectively. Therefore, it is necessary to reduce the amount of cereals per person by 5 kg/p and 25 kg/p so that the 2014 production could satisfy the population projected in 2024 and 2034. We found that cereal production will decrease with increasing temperature and decreasing precipitation according to the simulated scenarios, which might not satisfy the growing population in 2024 and 2034. This study provides a practical tool that can be used to provide policy makers with advice on food security assurance policy based on our current knowledge of the impending onset of climate change, including socio-economic statistics and the agricultural constraints of cereals in the 12 regions of Morocco

Development of an Integrated Model to Assess the Impact of Agricultural Practices and Land Use on Agricultural Production in Morocco under Climate Stress over the Next Twenty Years

Climate change is one of the major risks facing developing countries in Africa for which agriculture is a predominant part in the economy. Alterations in rainfall patterns and increasing temperatures projected by the Intergovernmental Panel on Climate Change (IPCC) could lead to a decline in agricultural production in many areas requiring significant changes in agricultural practices and land distribution. The study provided estimates of the economic impacts of climate change, compared these with historical impacts of drought spells, and estimated the extent to which the current Moroccan agricultural development and investment strategy, the Plan Maroc Vert, helps in agricultural adaptation to climate change and uncertainty. The aim of this study was to quantify the effects of climate change on the overall economy by using an integrated framework incorporating a computable general equilibrium model. A concomitant factor to climate change will be the increase in population and its distribution and level of consumption, which will also influence agricultural production strategies, the conversion of agricultural land, the type of irrigation, and technological development. We demonstrated how changes in cereal production and area, affluence, and climate (rainfall and temperature) can be acquired for 12 regions of Morocco and used to develop and validate an earth system model in relation to the environment and socio-economic level, which projects their impact on current and potential land use over the next 20 years. We used different mathematical equations based on cereal area and production, population, consumption (kg/person), and change in climate (temperature and rainfall) in bour and irrigated areas for the growing season of 2014 in 12 regions to project agricultural land use over the next 20 years. Therefore, several possible scenarios were investigated to explore how variations in climate change, socio-economic level, and technological development will affect the future of agricultural land use over the next 20 years, which in turn could have important implications for human well-being. Among the 12 Moroccan regions, only 4 had a surplus of cereal production compared to their local consumption. The increase in population will generate a cereal deficit in 2024 and 2034, thus lowering the average annual quantity available per capita of cereals from 204.75 to 160.61 kg/p in 2014 and 2034, respectively. Therefore, it is necessary to reduce the amount of cereals per person by 5 kg/p and 25 kg/p so that the 2014 production could satisfy the population projected in 2024 and 2034. We found that cereal production will decrease with increasing temperature and decreasing precipitation according to the simulated scenarios, which might not satisfy the growing population in 2024 and 2034. This study provides a practical tool that can be used to provide policy makers with advice on food security assurance policy based on our current knowledge of the impending onset of climate change, including socio-economic statistics and the agricultural constraints of cereals in the 12 regions of Morocco

Développement d'un nouveau procédé de décoffrage basé sur la polarisation du béton (Etude de l'aspect des parements en béton)

Pour pallier les désagréments liés aux méthodes actuelles de décoffrage, une nouvelle technique basée sur la polarisation du béton a été développée. Le principe, basé sur le phénomène de l électro-osmose, consiste à appliquer un potentiel électrique entre le ferraillage et le coffrage induisant ainsi le déplacement de l eau vers l interface béton/coffrage au niveau duquel se forme un film d eau en mesure d éviter l adhérence du béton avec le coffrage. Ce dispositif a permis également de vérifier la mise en place et la reproductibilité du béton par le biais de la résistance électrique. Une étude de faisabilité a mis en évidence le déplacement de l eau interstitielle ainsi que la possibilité de décoffrage. Afin d assurer une bonne qualité des parements et du décoffrage, les paramètres de polarisation (valeur de la tension, moment et durée de son application) ont été optimisés en fonction de la température ambiante et de la formulation du béton. Pour une température supérieure à 20+-2C, les conditions de polarisation sont identiques quelle que soit la formulation du béton. A des températures inférieures à 20+-2C, l ajout de l accélérateur de prise a été à chaque fois nécessaire et la valeur de la tension à appliquer a dû être augmentée. L ensemble des résultats a montré que l épaisseur du film d eau et la valeur de la conductivité du béton déterminent la qualité des parements et du décoffrage. L application des conditions optimales donne des parements de qualité similaire, voire meilleure dans certains cas, que celle des parements obtenus avec les huiles actuellement utilisées.Forts de ces résultats, la technique a été transposée in-situ et a donné des résultats satisfaisants.To overcome the inconveniences of current demoulding methods, a new technique based on the concrete polarization has been developed. The principle, based on the phenomenon of electro-osmosis, is to apply an electric potential between the reinforcement and formwork leading to water displacement to the concrete/formwork interface where a film of water, able to avoid the adhesion of the concrete with the formwork, is formed. This device also allowed verifying the casting and reproducibility of the concrete by using electrical resistance. A feasibility study proved the interstitial water displacement and demolding possibility. To obtain a good quality of facing and demolding, the polarization parameters (voltage value, time and duration of its application) have been optimized according to room temperature and concrete formulations. For temperatures above 20 +- 2 C, the polarization conditions are the same for all the concrete formulations. At temperatures below 20 +- 2 C, the addition of the accelerator was required at each time and the value of the applied voltage had to be increased. All results showed that the thickness of water film and the conductivity value of the concrete determine the quality of the concrete facings and demolding. The application of the optimal conditions provides a similar quality of concrete facings or even better in some cases, than those obtained with the demoulding oils currently used.With these results, the technique has been transposed in-situ and it gave satisfactory results.ARRAS-Bib.electronique (620419901) / SudocSudocFranceF