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Abstract

In recent years, the implementations of Micropiles have been increased extensively in large project constructions due to the unique advantages of this method comparing to concrete piles. The results of numerical analysis and centrifuge tests show that the efficiency and importance of micropiles can be considered as an effective solution. This research is designed to compare the newly designed system of microbulb with micropile applying a numerical modeling with finite element software Plaxis 3D foundation v1.6. We also used the FHWA code for a comparative study between micropiles and microbulbs. Then the effective factors were analyzed in order to decide which method is better between these two methods of micropile and microbulb. The results showed that the new microbulb system is an appropriate solution for improvement of mechanical properties of the soil, increase of bearing capacity and settlement decrease.

Abstract

Geopolymer offers significant promise to the construction world as a possible alternative to ordinary Portland cement (OPC). Like conventional Portland cement concrete, the matrix brittleness in geopolymer composites can be reduced by introducing suitable fibre reinforcement. A few investigations on fibre reinforced geopolymer composites are available. However there is still a gap to comprehend and enhance their performance. This paper describes the effect of incorporating micro polypropylene fibres on the strength and durability characteristics of geopolymer concrete. The engineering and durability properties like workability, compressive strength, split tensile strength, flexural strength, modulus of elasticity, and sorptivity of geopolymer concrete reinforced with micro polypropylene fibres is presented. The effect of the sulfuric acid attack on Geopolymer Concrete reinforced with micro polypropylene fibres is also discussed. The results show that hydrophobic characteristics of the micro polypropylene fibre led to weak contact with the geopolymer binder and hence weakened the mechanical performance of the fly ash based geopolymer matrix. However significant improvements in durability properties were noted.

Abstract

This research aims to define the degree of enjoyment in regions of Tabriz metropolis through innovative city indicators with an emphasis on the social and cultural indicators. In terms of practical purposes, the present study is of applied research type, and in terms of the nature of methodology, it is a comparative research. In this research, Shannon entropy method for weighing criteria is used to determine the weight of each of the indices under study, and a TOPSIS technique is applied in order to rank the regions of Tabriz metropolis to create the innovative city. Emphasizing on the social and cultural indicators, the findings of the research show that region 8 tops the ranking list and region 10 is ranked the last in terms of enjoyment through innovative city indicators. The result of this research indicates that the social and cultural indicators are not distributed equitably to fit well into an innovative city concept, and there is a focus on spatial distribution of indicators. Moreover, the results of this research indicate the incompatibility of the distribution of social and cultural indicators with the distribution of population across the city. Therefore, since innovation is the key to the development and expansion of cities as well as the equitable and rational distribution of services and facilities necessary for development and progress, the fair distribution of social and cultural indicators is essential for the realization of an innovative city.

Abstract

In the paper is presented a heating system installed in church and the interior climate generated. Thermal Comfort is the purpose of each designer, since the design stage and has to be ensure for the churchgoers, but even for the interior finishes. The heating system that uses hydronic radiators is evaluated trough the CFD modelling, in order to evaluate pro and contra arguments. The simulation has been made in a 3d simulation software environment, in Autodesk CFD with good results.

Abstract

The increasing demand in cement has inspired researchers in both developed and developing countries around the world to explore and consider alternative materials as partial replacement of cement both in concrete and in mortar. In this study, the influence of agricultural waste, particularly corn cob ash, (CCA) as pozzolanic material or supplementary cementitious material (SCM) on the physical properties and compressive strength of cement mortar was investigated. CCA was used as partial replacement of cement ranging from 0% to 20% by weight at water-cementitious ratio of 0.6 and mix proportion of 1 cementitious: 3 fillers. The physical properties evaluated for the mortar paste were setting time and consistency; and compressive strength of hardened mortar cube. The chemical analysis of CCA was conducted, and results indicated that the CCA used in this study is classified as Class C pozzolana with combined SiO2 + Al2O3 + Fe2O3 of 55.86%. The addition of CCA increases the initial and final setting time. The study also revealed that the addition of CCA in the mortar mix reduces the plasticity or fluidity of the paste. Further, the result indicated that the compressive strength of mortars with CCA decreased as the amount of CCA replacements increased in the mixture. The mortar pastes with varying amount of cement replacements, however, are superior for use as mortar for masonry construction.

Abstract

The flow around the ramp embedded in a pressurized tunnel is divided into the various zones immediately downstream of the ramp, including the cavity and the main zone of flow above the shear layer. The aeration coefficient of the flow from the lower surface (inside the cavity)(βlower) is a function of non-dimensional numbers which aerator geometry parameters such as cavity length to ramp height Lc/tr is considered as one of the most important parameters. Therefore, in the present study, OpenFOAM software and RNG k-ε turbulence model were used to simulate the flow to study the aeration effect on flow characteristics, so the range of aeration coefficient as 0%<β<10% for four ramps with different tr/d ratios is Applied, then by increasing the aeration coefficient in the range of 0%<β<16%, The dependency range of relative Cavity length Lc/tr to (β) was evaluated. In order to verify performance of the numerical model, experimental results of Manafpour test were used. The results of the research indicate that in the aeration of flow with aerator ramp, the height of ramp has more influence relative to ramp angle. Moreover the main Effectiveness of the aeration coefficient on the cavity length was limited to air percent less than 10%.

Abstract

Reinforcement of concrete components using FRP is one of the new strengthening methods that replaces old methods such as steel or concrete reinforcement. In spite of the extensive research on numerical analysis (limited components) of the behavior of components of reinforced concrete, few studies have been done on components of prestress concrete and its components limited modelling. In this study, using the Abaqus software, the behavior of four samples of concrete beams under periodic load, including original, prestress, reinforced with FRP sheets and influenced by both prestress and reinforced with FRP sheets (mix beam) was modelled. Prestress in structural fatigue showed that in both loading and unloading conditions, the prestress beam is more strength than the original beam.

Abstract

This paper deals with the behaviour of cement paste upon the addition of crushed polystyrene foam. Crushed polystyrene foam waste with a fill density of 13.97 kg/m3 and hydrated lime were used to prepare the foam. Three different types of samples S-1, S-2, and S-3 were prepared to observe the behaviour of cement pastes after the addition of different doses of foam in constant water/cement ratio. The volumetric ratio of EPS and cement paste were 1: 1.294; 1: 0.863; and 1: 0.647. In each type of sample, 0.28 water/cement ratio is maintained. Slump test was carried out in the fresh state and it has been found slump value was decreasing by increasing foam content in concrete sample. On the 7th and 28th day of curing process, the compressive strength test was carried out. Compressive strength and density of concrete samples also decreasing by addition of higher foam content. In addition, water absorption test and microscopic analysis tests were carried out on the 28th day of curing process. It has been found from the study that samples thermal conductivity is working proportionally.

Abstract

Today, research and development (R&D) indices are significant criteria for the development of countries. Therefore, the objective of the present study was to investigate the role and position of research and development units in construction industry from the perspective of construction management. The study is a descriptive survey research. The statistical population comprised the elite members and experts of research and development working in this field who were 81 individuals in total. The study employed Cronbach’s alpha to determine the reliability of the questionnaire. The study also exploited expert judgments of the elite members and experts of research and development in the construction industry to determine the validity of the questionnaire. For data analysis, the study deployed SPSS program. The findings reveal that the challenges existing in research and development centers are divided into the two groups of internal organizational problems and external organizational problems, and it is economically feasible to establish research and development units in the construction industry. In this regard, with a systematic view, the issue of research culture is proposed as the central point of the model.

Abstract

The relevance of the problem under study is attributed to the need to enhance reliability of the complex engineering systems used in forestry, agriculture, transport, machine engineering, etc. The purpose of the article is to build a mathematical model that would generalize reliability theory fundamentals from a perspective of the theory of dynamic systems based on the symmetry group concept determined by the probability function – dependence of no-failure (failure) probability on external time for system elements. The new approach to study this problem implies building of a multiplicative group under multiplication between no-failure (failure) probability rates as a number of units of the probability measure per unit of external (physical) time and the rate of functional (internal) time as the amount of external (physical) time per unit of the probability measure. The range of probability measures is [0, 1]; it is counted by the unit of measure defined by a set of elementary events. Based on the combination of functional times determined for each element of the system, the system becomes a single deeply integrated structure bound with external and internal time. Traditional reliability criteria of dynamic systems in the “space – time” functional space are dually related to their analogues in “functional time – probability”. Information credibility of the system dynamic state is enhanced by introducing additional confidence intervals of no-failure (failure) probability in conjugated times and their analysis. This study is intended for engineers, graduates, and students of technical universities.