Journal of Materials and Engineering Structures
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Prediction of average annual surface temperature for both flexible and rigid pavements
Get PDFThe surface temperature of pavements is a critical attribute during pavement design. Surface temperature must be measured at locations of interest based on time-consuming field tests. The key idea of this study is to develop a temperature profile model to predict the surface temperature of flexible and rigid pavements based on weather parameters. Determination of surface temperature with traditional techniques and sensors are replaced by a newly developed method. The method includes the development of a regression model to predict the average annual surface temperature based on weather parameters such as ambient air temperature, relative humidity, wind speed, and precipitation. Detailed information about temperature and other parameters are extracted from the Federal Highway Administration's (FHWA) Long Term Pavement Performance (LTPP) online database. The study was conducted on 61 pavement sections in the state of Alabama for a 10-year period. The developed model would predict the average annual surface temperature based on the known weather parameters. The predicted surface temperature model for asphalt pavements was very reliable and can be utilized while designing a pavement. The study was also conducted on seven rigid pavement sections in Alabama to predict their surface temperature, in which a successful model was developed. The outcome of this study would help the transportation agencies by saving time and effort invested in expensive field tests to measure the surface temperature of pavements
Elastic characterization by Ultrasonic waves of the unstandardized polycrystalline alloy 42500
Get PDFThe objective of this work is to determine the impact of the temper heat treatment (150, 160, 170, 180, 190, 200,220 and 240) °C on the evolution of the main elastic and structural properties of the alloy foundry AlSi7Zn3Cu2Mg (42500). This alloy will be subjected to precipitation hardening. This is one of the most successful methods to considerably improve the mechanical properties of the alloy, this allows choosing the compromise of high resistances while maintaining satisfactory ductility. The mechanical properties are governed by the combination of four factors: heat treatments, molding process, chemical composition and the shape of the specimen used. We used mainly four techniques namely: The ultrasonic method for the determination of the elastic characteristics, the Brinell hardness HB and the micro hardness Hv to identify the stress field, the Kcv resilience to provides information on fracture mode, brittleness and the impact resistance, and finally to completely identify the alloy, it will be followed by its metallography, microstructure and fracture surface in resilience.The purpose of this work is to study the structural hardening of the alloy AlSi7Zn3Cu2Mg (42500) by considering ten states: crude of casting noted: F taken as reference state. To improve the mechanical characteristics obtained from the crude of castingstate, a structural hardening heat treatment is carried out, the addition of magnesium is necessary in order to make the alloy sensitive to this specific heat treatment T46
RETRACTED : Elastic-plastic analysis of reinforced composite materials
Get PDFThis article has been retracted at the request of the Editors-in-Chief, according to the Publication Ethics Policy and Publication Malpractice Statement.Please see : http://revue.ummto.dz/index.php/JMES/about/editorialPolicies#custom-2 This note is published, 25 June 202
Green function of curved rail-beam
Get PDFDans cet article, nous avons étudiés le comportement dynamique du rail sous charges inclinés, le rail est modélisé comme poutre courbée sous charges latérales.Lorsqu'un train entre dans un virage, Deux sources conduisent à ces forces latérales qui ont été rarement étudiés par les chercheurs précédents: les forces d'action du train résultent des forces de la barre d'attelage (due les forces centrifuges) et des forces qui se développent en raison de l'interaction dynamique du véhicule et du rail.Le rail est modélisé comme une poutre infinie selon la théorie d'Euler-Bernoulli.L’utilisation d’une section élémentaire courbée, aide-nous de trouver les sollicitations qui agissent la poutre, et d’écrire l’équation différentielle du système.L’utilisation de la méthode des résidus permet de déterminer la fonction de Green associée à l’équation différentielle régissant le comportement vibratoire du système rail de la poutre libre.Dans cet article, on étudie le comportement dynamique du rail sous charges inclinées. Le rail est modélisé comme une poutre courbée sous charges latérales. Lorsqu'un train amorce un virage, deux sources conduisent à ces forces latérales qui ont été rarement étudiées par les précédents chercheurs : les forces d'action du train résultent des forces de la barre d'attelage (due les forces centrifuges) et des forces qui se développent en raison de l'interaction dynamique du véhicule et du rail. Le rail est modélisé comme une poutre infinie selon la théorie d'Euler-Bernoulli. L’utilisation d’une section élémentaire courbée permet d'établir les sollicitations qui agissent sur la poutre, et d’écrire l’équation différentielle du système. L’utilisation de la méthode des résidus permet de déterminer la fonction de Green associée à l’équation différentielle régissant le comportement vibratoire du système rail de la poutre libre.In this article, we study the dynamic behavior of the rail under inclined loads. The rail is modeled as a curved beam under lateral loads. When a train enters a curve, two sources lead to these lateral forces that have rarely been studied by previous researchers: the forces of action of the train result from the forces of the drawbar (due to centrifugal forces) and forces that develop due to the dynamic interaction of the vehicle and the rail.The rail is modeled as an infinite beam according to the Euler-Bernoulli theory. The use of a curved elementary section, allows to establish the solicitations that act the beam, and to write the differential equation of the system. The use of the residue theorem allows determining the Green function associated with the differential equation governing the vibration behavior of the rail system of the free beam
Effect of Lime Powder and Metakaolin on Fresh and Hardened Properties of Self Compacting Concrete
Get PDFThis study investigated the fresh and hardened properties of Self-Compacting Concrete (SCC) with different types and amounts of admixtures. Six mixes were prepared by replacing 30% of cement with different percentages of fly ash (FA), lime powder (LP) and metakaolin (MK). Water- Cement ratio was kept constant at 0.41 and superplasticizer dosage of 1% by weight of cement. The filling and passing ability were investigated through Slump Flow, J-Ring, V-funnel and L-box test before filling the moulds. The compressive strength of hardened SCC cubes was also measured after specified days of curing (7, 14, 28, 60 90 days). The workability test results showed that as FA was replaced by increasing percentages of LP and MK, the mixes became dense and hence less workable. It was observed that the compressive strength showed an increase with increasing percentage replacement of FA with LP and MK. This increase was higher for mixes with MK than that of mixes with LP
Reviewing the Carbonation Resistance of Concrete
Get PDFThe paper reviews the studies on one of the important durability properties of concrete i.e. Carbonation. One of the main causes of deterioration of concrete is carbonation, which occurs when carbon dioxide (CO2) penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Carbonation is a major cause of degradation of concrete structures leading to expensive maintenance and conservation operations. Herein, the importance, process and effect of various parameters such as water/cement ratio, water/binder ratio, curing conditions, concrete cover, super plasticizers, type of aggregates, grade of concrete, porosity, contaminants, compaction, gas permeability, supplementary cementitious materials (SCMs)/ admixtures on the carbonation of concrete has been reviewed. Various methods for estimating the carbonation depth are also reported briefl
Durability Properties of Self Compacting Concrete containing Fly ash, Lime powder and Metakaolin
Get PDFThis paper investigates the durability properties of Self-compacting concrete (SCC), with different amounts of fly ash (FA), lime powder (LP) and metakaolin (MK). A total of 6 mixes were prepared that have a constant water-binder ratio (w/b) of 0.41 and superplasticizer dosage of 1% by weight of cement. In addition to compressive strength, the durability properties of SCC mixes were determined by means of Initial surface absorption test (ISAT) and Capillary suction test. The test results indicated that the durability properties of the mixes appeared to be very dependent on the type and amount of the mineral admixture used; the mixes containing MK were found to have considerably higher permeability resistance. Good co-relation between strength and absorption were achieved
Seismic Retrofitting: Reinforced Concrete (RC) shear wall versus Reinforcement of RC element by Carbon Fiber Reinforced Polymer (CFRP) using PUSHOVER analysis
No full textSeismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004). Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP) applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code[1]
Behaviour of slag HPC submitted to immersion-drying cycles
Get PDFCet article constitue une partie d’une synthèse des travaux élaborés conjointement au Laboratoire de Génie Civil et de Génie Mécanique de l’INSA de Rennes et l’Unité de Recherche : Matériaux, Procédés et Environnement de l’Université de Boumerdès. Un des objectifs visés était en effet de valoriser, par des études de variantes, l’utilisation des ajouts cimentaires locaux dans la formulation des bétons à hautes performances (BHP). La contribution liante des additions minérales aux propriétés physiques, mécaniques et de durabilité des bétons a été évaluée par une méthodologie expérimentale originale permettant de subjuguer leur effet granulaire. Les résultats obtenus montrent que la contribution du couple ciment - laitier à la densification de la matrice est supérieure à celle obtenue lorsque le ciment n’est pas substitué par l’addition. Par conséquent, une amélioration significative des performances des bétons formulés a été observée, ceci malgré l’action préjudiciable des cycles immersion - séchage maintenus pendant 365 jours.Cet article constitue une partie d’une synthèse des travaux élaborés conjointement au Laboratoire de Génie Civil et de Génie Mécanique de l’INSA de Rennes et l’Unité de Recherche : Matériaux, Procédés et Environnement de l’Université de Boumerdès. Un des objectifs visés était en effet de valoriser, par des études de variantes, l’utilisation des ajouts cimentaires locaux dans la formulation des bétons à hautes performances (BHP). La contribution liante des additions minérales aux propriétés physiques, mécaniques et de durabilité des bétons a été évaluée par une méthodologie expérimentale originale permettant de subjuguer leur effet granulaire et pouzzolanique. Les résultats obtenus montrent que la contribution du couple ciment - laitier à la densification de la matrice est supérieure à celle obtenue lorsque le ciment n’est pas substitué par l’addition. Par conséquent, une amélioration significative des performances des bétons formulés a été observée, ceci malgré l’action préjudiciable des cycles immersion - séchage maintenus pendant 365 joursThis article is part of a summary of the work developed in conjunction with the Laboratory of Civil Engineering and Mechanical Engineering from INSA Rennes and Research Unit: Materials, Processes and Environment, University of Boumerdes. One of the objectives was indeed to promote, through studies of variants, the use of local cementitious additions in the formulation of high performance concretes (HPC). The binding contribution of mineral additions to the physical, mechanical and durability of concrete was evaluated by an experimental methodology to subjugate their original granular and pozzolanic effect. The results show that the contribution of couple cement -slag intensification of the matrix is higher than that obtained when the cement is not substituted by addition. Therefore, a significant improvement in performance of concretes was observed, despite the adverse action immersion cycles - drying maintained for 365 days
Evaluating the Durability Properties of Self Compacting Concrete made with Recycled Concrete Aggregates
Get PDFThis paper reports the durability properties of Self Compacting Concrete (SCC) made with Recycled Concrete Aggregates (RCA) as partial/full replacement of Natural Coarse Aggregates (NCA). The effect of RCA on fresh properties of SCCs was measured using slump flow test, V-funnel test, L-box test and J-ring test. Whereas the durability properties like such as initial surface absorption, water permeability, capillary suction and rapid chloride penetrability were investigated to study the effect of varying content of RCA on SCC. The compressive strength of different SCC mixes was also determined for reference. The results indicate that increasing the content of RCA in SCC leads to deterioration in durability related properties of SCC. The compressive strength has also been found to decrease with increasing RCA content. It has been seen that the reduction in the performance has been marginal up to 50% replacement level of RCA, but 100% replacement of RCA has been found to significantly affect the durability related properties and compressive strength