Authors:Panga Narasimha Reddy and Javed Ahmed Naqash
The possibility of using mineral admixtures as a replacement for cement may reduce the carbon dioxide emission, which causes global warming and climatic changes on the environment. The objective of this study is to investigate the properties of early strength concrete produced with a constant replacement of alccofine (i.e. 25% by mass) and a new generation of chemical admixture that is Polycarboxylate ether. The constant dosage of alccofine and different proportions of polycarboxylate ethers are mixed in concrete and tested for workability and mechanical properties of concrete. Response surface method was applied to predict, validate and optimize the experimental data using regression equation. The results show that the performance of concrete improves with the addition of alccofine and Polycarboxylate ether into concrete.
Authors:Mykola Sysyn, Vitalii Kovalchuk, Ulf Gerber, Olga Nabochenko and Andriy Pentsak
Railway ballast tamping is one of the cost-expensive renewal and maintenance works of railway superstructure. The quality of ballast consolidation influences its resistance to residual deformations and long-term deterioration of track geometry. The process of ballast compaction along the sleeper under the vibration loading is complex and depends on many factors. The ballast flow processes under the vibration loading can produce both consolidation and un-consolidation of ballast material. The present study is devoted to the experimental investigation of ballast consolidation inhomogeneity. The method of ballast local consolidation measurement is proposed. The method is based on the velocity of impact wave propagation that is measured with device. The application of modern microcontroller and sensor techniques provided simple and reliable multi-point velocity measurements in a ballast layer. That enables well enough spatial resolution of ballast consolidation inhomogeneity. The measurement analysis has shown more than 4 times higher consolidation under the sleeper center than for unconsolidated ballast.
In the present study, the performance of concrete sandwich panel against fire and axial load has been considered. A finite element model of a sandwich wall is presented and evaluated the performance under different temperature (200, 400, 600 °C. The ratio of width, thickness and length of wall are constant and the axial load enters on the top of wall. The maximum displacement and stress in different models shows the capacity of wall is increased at high temperature. The displacement has dramatically increased at temperature loading of 800 °C and it has gained which shows poor efficiency of wall at high temperatures.
This paper discusses the control of the electric energy consumption in a household equipped with smart devices. The household consumption pattern is the result of a two-level optimization framework. The scheduling of the electric appliances is determined by the first optimization, receiving Time of Use tariffs proposed by the utility company. The scheduler considers the consumer's preferences on the powering on for each appliance.
Secondly a model predictive controller is developed to control the electric heating system based on energy constraints resulting from the appliance scheduling.
Simulations show the energy efficiency and an optimized electricity cost of the strategy proposed.
Authors:El Mehdi Echebba, Hasnae Boubel, Oumnia Elmrabet and Mohamed Rougui
In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions.
This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.
A welded steel protective cover used for the heat treatment of steel sheet coils is investigated. The protective cover is made of austenitic stainless steel and consists of three main segments, welded together, which have 1400 mm height each. The plate thicknesses at the lower, middle and upper segments are different. The investigation aimed to improve the lifetime and the number of heat cycles of the protective cover by changing the geometry, the effect of the thicknesses and the material. Damaged covers have been evaluated, made calculations of stress and deformations, and carried out a series of finite element simulations. Both horizontal and vertical corrugated sheets were simulated and compared. The non-corrugated plates were also investigated, but their performance was behind the corrugated ones. The original geometry and that of the horizontal corrugated plate are identical from the stress level point of view. The vertical position of the corrugated plate provided a better result than the horizontal one. The calculated and simulated results for the original geometry are close to the measured damage.
The mechanical and physical properties of the crushed aggregate have been studied. The properties of crushed aggregate, which produced from recycled aggregate concrete is not discussed in the literature yet despite it could be a choice in some circumstances like in case of demolishing the structures that already constructed by recycled aggregate concrete. Twenty-two types of self-compacting high-performance concrete made by coarse natural aggregate and coarse recycle concrete aggregate have been crushed and their properties have been studied. The main findings of the present study that, the Los Angeles index and water absorption of crushed aggregate is affected by the coarse recycled concrete aggregate dosage in its parent concrete, as well as, incorporating cement replacing materials in parent concrete help to enhance the abrasion resistance of crushed aggregate.
The historic centers to retain their liveliness and vibrancy should be able to grow and change. It is a big challenge for the contemporary architecture to balance the socio-economic needs of the city and its community in one hand, and protection of the cultural heritage on the other. The aim of this study is to analyze the incorporation of the new structures in the historical context. How can the new structures harmoniously be incorporated in the historic centers without endangering their cultural heritage values? The paper discusses how to design a new contemporary shopping mall in the Historic Center of Prizren in order to create an attractive area and at the same time avoiding deterioration of the historical place.
Stability is one of the most critical problems in the design of welded metal structures, since in many cases instability causes failure or collapse of the structures. The present study aims to show the minimum mass design procedure for welded steel box columns loaded by a compression force. The normal stresses and overall stability are calculated for pinned columns. The dimensions of the box columns are optimized by using constraints on global stability, local buckling of webs and flanges. Different design rules and standards are compared: Eurocode 3, Japan Railroad Association, American Petroleum Institute, and American Institute of Steel Construction. The calculations are made for different loadings, column length and steel grades. The yield stress varies between 235 and 690 MPa. Optimization is carried out using the generalized reduced gradient method in Excel solver. Cost calculations and comparisons show the most economical structure.