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Investigations of the Influence of Polystyrene Foamed Granules on the Properties of Lightweight Concrete

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.

Open access
Role and Position of R&D Units in the Construction Management Industry

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.

Open access
System Analysis of Reliability Theory Foundations

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.

Open access
Technical-Economical Comparison Between Vertical Link Beam and Knee Brace Systems in Mid-Rise Steel Buildings

Abstract

In knee brace and shear panel systems, unlike eccentric braced frames, energy absorption is achieved through plastic deformation when sub-members yield by shear forces or bending moments caused by bracing members during severe earthquakes. Several studies have been conducted on the behavior of these two systems which resulted in design methods to obtain the best structural performance. The present study attempted to design frames using these methods, and then to compare them in terms of technical and economic factors. In this regard, to obtain a pattern of the frames behavior, a 3-span 5-storey frame was modeled for three different types of brace system (coaxial, knee and shear panel) using ANSYS software. After performing pushover nonlinear static analysis, behavior coefficients were determined and the force-lateral displacement curves of the systems were compared. In the next step, 3-span 5- 8- and 12-storey frames were analyzed and designed using ETABS software and were compared in terms of the parameters such as relative lateral displacement, normal period of system, structural weight, and shear force into foundation. The results indicate that using the above-mentioned systems, structure will exhibit more ductility which leads to reduced design base shear. The forces applied to main structural members (beams, columns, and braces) are reduced by the use of knee brace and shear panel systems. This will affect the design and sometimes increases or decreases weight of these members.

Open access
Thermal Comfort Modeling of a Church Heated with Static Heaters

Abstract

This paper evaluates a static heating system from a church. They are presented in almost every church. Temperature distribution in the church is done in 2d plane. The simulation is presented on a particular example, the Dormition of the Mother of God Church from Jassy, Romania. The heating system had been simulated in FLUENT and the consequences over the interior climate in the church are showed. An important issue is the impact of this system over the artwork, the church being rise in XVIII century.

Open access
Utilization of Rubber Powder of Waste Tyres in Foam Concrete

Abstract

Foam concrete or light concrete has become increasingly recognizable in commercial and construction field. Foam concrete is not just light in its weight but also light in cost, as there is no coarse aggregate needed in its production. Application of foam concrete is limited due to the fact that it is not as strong as conventional concrete in terms of strength and rigidness. Therefore, this study is to investigate the potential of foam concrete incorporating with rubber powder of waste tire and admixture as an additive material to improve its strength and workability. Thus, the use of rubber powder in this study could enhance the strength by filling the voids in foam concrete. The amount of rubber powder added as additive in foam concrete is 0%, 5%, 10%, 15% and 20% respectively. The amount of plasticizers used is limited to less than 0.4% to the weight of cement. The mix design was set to achieve density of 1800kg/m3. The workability of foam concrete is decreasing as the percentage of rubber power was increasing. The foam concrete containing 5%of rubber powder has highest compressive strength with value of 20.6 MPa for 7 days water curing and 22.3 MPa for 28 days water curing. Significantly showing an increase of 1.7 MPa. The highest value of tensile strength for both air curing 7 and 28 days are 1.86 MPa and 1.97 MPa also held by 3% of rubber powder mix. As a conclusion the optimum rubber powder content to be used in foam concrete is 5% that gives the highest results in terms of workability and strength.

Open access
Water Loss Reduction in Water Distribution Networks. Case Study

Abstract

Water losses on the potable water distribution networks represent an important issue; on the one hand, water loss does not bring money and on the other hand, they modify water flow and pressure distribution on the entire system and this can lead to a cut-off of the water supply. A stringent monitoring of the water distribution network reduces considerably the water losses. The appearance of a leakage inside the distribution network is inevitable in time. But very important is its location and repair time – that are recommended to be as short as possible. The present paper analyses the hydraulic parameters of the water flow inside a supply pipe of a looped network that provides potable water for an entire neighbourhood. The main goals are to optimize these parameters, to reduce water losses by rigorous monitoring and control of the service pressure on the supply pipe and to create a balance between pressure and water flow. The presented method is valid for any type of distribution network, but the obtained values refer strictly to the analysed potable water distribution looped network.

Open access
Automation of the Calibration Process as One of the Directions of Development of Military Metrology

Abstract

The article discussed aim to introduce readers to the problem matter in connection with the changes taking place within the area related to the issue of metrology in the Armed Forces of the Polish Republic. The article depicts the current situation along with the changes, which took place over the recent years, in the structures of Military Metrology, and it presents the major directions of its development, with particular emphasis on the automation of the calibration process.

Open access
Dynamic Analysis of the Tubular Linear Actuator With Permanent Magnets

Abstract

In this paper a results of a transient analysis of the linear actuator is presented. The linear actuator consist of the three cylindrical unmovable coils surrounded by a soft ferromagnetic case, a runner made from sequence of ferromagnetic and permanent magnet rings. The model of the linear actuator was implemented into two software: the Comsol Multiphysics and the Matlab-Simulink. Both environments are commonly used in simulation analysis, but the first one uses Finite Element Method (FEM) and the second one uses Ordinary Differential Equations (ODE). Moreover, the dynamic model was analysed in Matlab-Simulink software with value of electromagnetic phenomena implemented from Comsol Multiphysics. Comparison was made due to the time needed for calculation, accuracy of the simulation model as well as the as utility for further optimization process.

Open access
ERRV as an Emergency Protection Components in the Offshore Sector Activities

Abstract

The article in the short form presents a problem of protection of human activity in the offshore sector. Authors particularly focused on the analysis and presentation of highly specialized vessels — ERRV (Emergency Response and Rescue Vessels) which are specially designed to ensure safety in the offshore sector; their equipment and its appropriate use. Specific solutions and measures, their capabilities and limitations were presented.

Open access