Journal of Materials and Engineering Structures
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Algerian Seismic Regulations RPA 99 - Version 2003 for Reinforced Concrete Building Structures: Interpretations and Proposals
Get PDFLa règlementation parasismique Algérienne RPA99 - Version 2003 se traduit par un ensemble de règles de conception et de calcul qui nécessite, pour leur bonne application, la maîtrise de leur interprétation. Cependant, il a été constaté que ces règles ne sont pas toujours appliquées de façon satisfaisante. Le présent article présente des éclaircissements sur certains articles qui peuvent poser des problèmes d’interprétation, ainsi que des propositions de modification pour une future révision. Cet article s'arrête aussi sur certaines mal-pratiques dans l’application de ces règles.La règlementation parasismique Algérienne RPA99 - Version 2003 se traduit par un ensemble de règles de conception et de calcul qui nécessite, pour leur bonne application, la maîtrise de leur interprétation. Cependant, il a été constaté que ces règles ne sont pas toujours appliquées de façon satisfaisante. Le présent article présente des éclaircissements sur certains articles qui peuvent poser des problèmes d’interprétation, ainsi que des propositions de modification pour une future révision. Cet article s'arrête aussi sur certaines mal-pratiques dans l’application de ces règles.The Algerian seismic design regulations RPA 99 - Version 2003 are a set of design and calculation rules that require their good interpretation for a proper application. However, it has been found that these rules are not always applied in a satisfactory way. This paper presents clarifications regarding some provisions that may raise interpretation issues, as well as modification proposals of some provisions for future revision. This paper focuses also on some misconceptions in the application of these rules.
Editorial
Get PDFIt is already three years since the launch of the first issue of the Journal of Materials and Engineering Structures (JMES) in 2014, with eleven (11) issues already published. We are preparing to start this fourth year with the publication of this twelfth issue, which contains five articles from four different countries (Egypt, Morocco, India and Nigeria).The first article is devoted to the study the effect of stirrups as shear reinforcement in enhancing the punching strength of interior slab-column connections. The parameters of the study are the presence of shear reinforcement and stirrups concentration around the supporting column. The article shows that a good distribution of the stirrups on the critical perforation shear zone is an efficient solution to enhance not only the punching shear capacity but also the ductility of the connection.The second paper deals with the dislocation nucleation phenomena in nanomaterials obtained by hetero-epitaxial growth of thin films on substrates having lattice mismatch defects. The article develops theoretical calculation on the principle of nucleating edge dislocations from free lateral surfaces by the theoretical calculation, using the method of image stress and energy study.The third article presents a study the development of Self Compacting Concrete (SCC) using copper slag (CS) as fine aggregates with partial and full replacement of sand. The authors observed that the fluidity of SCC mixes was significantly enhanced with the increment of copper slag. The results of the tests showed that copper slag has the potential to replace sand in the range of 40-60% to obtain SCC with desirable fresh and strength properties. The use of copper slag (industrial waste) reduces the dosage of superplasticizer, consumption of natural resources which is a solution to decline the cost of concrete and boon for construction industry.The fourth paper aims to assess geotechnical properties of uncemented/cemented clayey soil incorporated with waste crumb rubber. Authors concluded that unconfined compressive strength and split tensile strength of rubberized cemented clayey soil decreases with the increase of the percentage of crumb rubber whereas the axial, and diametral strain are found to be increased with the addition of crumb rubber up to 5% after that it starts to decrease. The CBR values (California Bearing Ratio), swelling pressure, and toughness index of uncemented/cemented clayey soil was significantly affected by incorporation of crumb rubber.The fifth paper investigated the effect of fly ash, silica fume and metakaolin on the air permeability of Portland cement concrete at equal water/cement ratios and strengths. At equal water/cement ratios, while fly ash binary cement concretes have higher coefficients of air permeability than Portland cement concrete due to delayed pozzolanic reactivity, silica fume and metakaolin binary cement concretes have comparable coefficients with Portland cement concrete. The ternary cement concretes have coefficients comparable with that of Portland cement concrete. The author concluded that high volume fly ash would be required to increase the resistance of concrete to air permeability at equal strength.During the first few years of JMES existence, we have tried to respect the regularity in the publication of the issues with a quarterly frequency, and by publishing for each issue a number of articles ranging from four to five with the goal of maintaining a certain level of scientific quality which reflects the ambitions and objectives that JMES has set itself.At the moment when we are closing this twelfth issue, JMES is being evaluated by two of the most respectable scientific databases which are DAOJ (Directory of Open Access Journals - https://doaj.org) and COMPENDEX (https://www.elsevier.com/solutions/engineering-village/content/compendex). All this would not have been possible without the assistance and the help of expert colleagues, who have done us the honor of evaluating the numerous papers submitted to the JMES during its first three years of existence. We are also taking advantage of this opportunity to renew our confidence in the members of the Reading Committee for the next years.The journal JMES which is yours continues its reflection on its evolution and aims to position itself as a scientific journal indexed in scientific databases respectable and recognized by the international scientific community. It is in this mind that the Editorial team reiterates its call to all national and foreign researchers to contribute by the quality of their articles to the success of JMES which is theirs and which is a tool for promotion and sharing of their research through their publication.We wish you a good reading. Editor in Chief: Dr. Farid ASMA, Senior lecturer, Department of mechanical engineering, University of Mouloud Mammeri, Tizi Ouzou, AlgeriaAssociate Editor: Dr. Hocine HAMMOUM, Senior lecturer, Department of civil engineering, University of Mouloud Mammeri, Tizi Ouzou, Algeria
Natural Gas Driven Vehicles Safety and Regulatory Regime - Challenges in Bangladesh
Get PDFNatural gas driven vehicles (NGV) is common in Bangladesh first introduced around 1995. Be that as it may, situation has changed because of minimal effort of CNG as fuel. The legislature additionally empowered the change of private vehicles by making a few strategy activities as Bangladesh has natural gas reserve, cost economy, low emission. Now passenger automobile like car, bus, and even agricultural vehicles are utilizing CNG as fuel. Faulty cylinders or other CNG-related kits in NGV not only endanger the lives of the passengers of the vehicles, but also of others somehow remaining close to the accident spots. The safety aspect of CNG runs vehicles are beyond regular and strict monitoring, even out of consideration. The objective of this paper is to find out the present scenario of the NGV of Bangladesh and safety perspective in compare to the CNG safety act of Bangladesh. For this purpose, other CNG safety standard of first world country along with exporter country is under consideration. This paper reviews the options available to policy makers in their efforts to reduce the causalities associated with NGV transport. It provides a summary of the categories of negative impacts targeted together with the specific policy initiatives available. The actions for regulation taken by policy makers and foregoing challenges are underlined. To fight against the challenges a framework has proposed
Numerical simulation of Wind induced mean interference between two tall buildings
Get PDFThe assessment of wind loads on structure is generally carried out using existing codes/standards. The specifications of these codes are based on wind tunnel experiment performed on an isolated building. However, the buildings seldom exist in isolated condition. Neighbouring building may either increase or decrease the wind loads on principal building, this effect is known as interference effect. In this paper interference effect between two buildings is studied through numerical simulation using ANSYS CFX. Total drag force and interference factors for the principal building is calculated in the presence of interfering building having height ratio of 0.5, 0.75,1, 1.25, and 1.5. The results show that the upstream interfering buildings cause certain shielding effect by decreasing the mean wind load on the downstream principal building. However an amplification effect is also observed for certain location of the interfering building on upstream side. For buildings of the same cross-section, the interference factor (IF) decreases with the increase of the height of interfering building, indicating increase in the shielding effects. However the shielding effect on principal building is found to be significant when the heights of interfering buildings range from 0.75 to 1.5 of the height of the principal building. The along-wind force of the downstream principal building reduced to zero when the upstream interference building of height ratio more than one was two to three times the building breadth away from the principal building
A pile-up of edge dislocations to relax Misfit strain
Get PDFIt is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture of the material. For a crystalline film on a non-deformable substrate, a key problem involves the movement of dislocations in the thin film. An analysis of this problem provides insight into both the formation of misfit dislocations in epitaxial thin films and the high strengths of thin metal films on substrates. We develop in this paper, theoretical calculations for dislocation nucleation phenomena in nanomaterials obtained by hetero-epitaxial growth of thin films on substrates having lattice mismatch defects. Atomic force microscopy observations showed the nucleation of dislocations from free lateral surfaces to relax the "misfit" strain, here we explain the principle of nucleating edge dislocations from these surfaces by the theoretical calculation, using the method of image stress and energy study. We begin, by treating the case of a single dislocation and then generalize the work at a pile-up of n interface dislocations.
Pilot Experimental Tests on Punching Shear Strength of Flat Plates Reinforced with Stirrups Punching Shear Reinforcement
Get PDFFlat plates are favor structure systems usually used in parking garages and high-rise buildings due to its simplicity for construction. However, flat plates have some inherent structural problems, due to high shear stress surrounding the supporting columns which cause a catastrophic brittle type of failure called "Punching Shear Failure". Several solutions are used to avoid punching shear failure, including the use of drop panels or punching shear reinforcement. The latter is being a more sophisticated solution from the structural ductility, the architectural and the economical point of view. This study aims at investigating the effect of stirrups as shear reinforcement in enhancing the punching strength of interior slab-column connections. A total of four full-scale interior slab-column connections were tested up to failure. All slabs had a side length of 1700 mm and 160 mm thickness with 200 mm x 200 mm square column. The test parameters were the presence of shear reinforcement and stirrups concentration around the supporting column. The test results showed that the distribution of stirrups over the critical punching shear zone was an efficient solution to enhance not only the punching shear capacity but also the ductility of the connection. Furthermore, the concentrating of stirrups shear reinforcement in the vicinity of the column for the tested slabs increases the punching shear capacity by 13 % compared to the uniform distribution at same amount of shear reinforcement
Effects of Supplemetary Cementitious Materials on the Air Permeability of Concrete
Get PDFIn order to support the use of cement combination concrete in construction, this paper investigated the resistance of Portland cement and some binary and ternary cement concretes containing fly ash, silica fume and metakaolin to air permeability at equal water/cement ratios and strengths. At equal water/cement ratios, while fly ash binary cement concretes have higher coefficients of air permeability than Portland cement concrete due to delayed pozzolanic reactivity, silica fume and metakaolin binary cement concretes have comparable coefficients with Portland cement concrete due to their higher fineness, improved particle packing and higher pozzolanic reactivity. Consequently, the ternary cement concretes have coefficients comparable with that of Portland cement concrete. At equal strengths, while silica fume and metakaolin binary cement concretes have higher coefficients than Portland cement concrete, fly ash binary cement concretes have lower coefficients which reduced with increasing content of fly ash. Consequently, all the ternary cement concretes have lower coefficients which reduced with increasing total replacement level due to the beneficial effect of fly ash. Hence, high volume fly ash would be required to increase the resistance of concrete to air permeability at equal strength
Analyse du coup de bélier dans une conduite forcée dans le cas d’une fermeture de vanne. Partie 2: Pertes de charges concentrées en aval
Get PDFIn our previous study (Part 1); by using the graphic of Bergeron, we have drawn the relationships which allow calculating flows and pressures at the valve and the reservoir, considering that pressure losses are negligible. Now, we assume in this second contribution that these pressure losses are concentrated downstream of the pipe, just at the entry of the valve. The study will focus on water hammer-induced by a slow closing of the valve. A practical example will be presented at the end of this work in order to illustrate the exposed method. Dans notre première partie de l’analyse du coup de bélier, en nous aidant de la construction graphique de Bergeron, nous avons tiré les relations qui permettent de calculer les débits et les pressions au niveau de la vanne et du réservoir, en considérant les pertes de charges négligeables. Dans cette deuxième contribution, nous supposons que ces pertes de charge sont concentrées en aval de la conduite, juste à l’entrée de la vanne de sectionnement. L’étude portera essentiellement sur le coup de bélier induit par la fermeture lente de la vanne. Ainsi pour illustrer la méthode de calcul, un exemple de calcul pratique sera présenté à la fin de cet article. Dans notre première partie de l’analyse du coup de bélier, en nous aidant de la construction graphique de Bergeron, nous avons tiré les relations qui permettent de calculer les débits et les pressions au niveau de la vanne et du réservoir, en considérant les pertes de charges négligeables. Dans cette deuxième contribution, nous supposons que ces pertes de charge sont concentrées en aval de la conduite, juste à l’entrée de la vanne de sectionnement. L’étude portera essentiellement sur le coup de bélier induit par la fermeture lente de la vanne. Ainsi pour illustrer la méthode de calcul, un exemple de calcul pratique sera présenté à la fin de cet article
Evaluation of enhanced particle swarm optimization techniques for design of RC structural elements
Get PDFIn this paper, the use of extended versions of basic Particle Swarm Optimization (PSO) to Reinforced Concrete (RC) structural elements has been presented. The aim of extended versions of basic particle swarm optimization techniques to seek the global optima by maximizing the explorations area and minimizing the exploration time. Optimal sizing and reinforcement of RC structural members have been found by employing these techniques. The algorithms are coded in C++ and their effectiveness was tested in some benchmark mathematical functions. The different variables of each structural element have been considered as continuous functions and rounded off appropriately to imbibe the practical relevance of the present study