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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
Comparative Analysis of Structure-From-Motion Software’s –An Example of Letychiv (Ukraine) Castle and Convent Buildings

Abstract

Letychiv (pl. Latyczów) is a town located in central Ukraine in the Khmelnytskyi Oblast. It has a unique and complicated history. Second World War left it in ruin, destroying buildings, infrastructure and decimating its once large population. Perhaps the most prominent part of the town currently is the building Dominican convent with adjoin Letychiv Assumption Church. This object is surrounded by what is left of the previously impressive Letychiv Castle, founded by Jan Potocki in 1598. Past 30 years have been dedicated by this small Catholic parish towards rebuilding monastery-castle-church complex. Since this is an ongoing project, it was decided to perform a photographic inventory of the current state of the construction and to create a 3D digital model of the castle, facade of the church and monastery, and the altar. This task have proven to be difficult due to complicated structure of the object. Facades and inner parts of the church are almost white with limited number of distinctive elements, painted in pail gold. Elements other than white are almost identical to each other. It leads to various errors in the processing of Structure-from-motion. This article describes how various versions of SfM algorithm work thru mention difficulties, compares results in terms of accuracy, level of detail and overall look. It also describes how SfM can help to document various stages of restoration of important historical objects.

Open access
Comparison of Airborne Laser Scanning of Low and High Above Ground Level for Selected Infrastructure Objects

Abstract

Along with the development of the technology of drone construction (UAV - Unmanned Aerial Vehicles), the number of applications of these solutions in the industry also grew. The aim of the research is to check the accuracy of data obtained using the new technology of UAV scanning and to compare them with one that is widely spread - high-altitude airborne Lidar, in terms of quality and spectrum of applications in industry and infrastructure. The research involved two infrastructure objects: a reinforced concrete one-span bridge and Lattice transmission tower with powerlines. The density of measurement, internal and external cohesion of point clouds obtained from both methods were compared. Plane fitting and deviation analysis were used. The data of UAV origin in both cases provided a sufficient density, allowing the recognition of structural elements, and internal coherence and precision of measurements important in modeling. The study shows that UAV mounted scanning may be used in the same applications as Airborne Lidar, as well as in other tasks requiring greater precision.

Open access
Damage Detection of Concrete Gravity Dams using Hilbert-Huang Method

Abstract

Damage detection in concrete gravity dams using Hilbert-Huang Method, as one of the most common signal processing techniques, is studied in this research. After considering a typical geometry for dams, damage is modelled by a reduction in the modulus of elasticity in the dam’s body (in three levels of damage) and in different areas of the structure. The dam is excited by a horizontal earthquake and the primary natural frequencies of the dam are calculated by applying Hilbert-Huang Method to the measured response, which is the acceleration of five points in the system. Based on the changes in the frequencies of the damaged and undamaged structure, a parameter, called relative frequency error, has been introduced. The results show that the proposed criterion used in this study can not only properly identify the location of damage but also predict the severity of the structural damage in concrete gravity dams accurately.

Open access
Effects of Fly Ash on Mechanical Properties of Concrete

Abstract

Cement is a common and widespread building material over the world. Similarly, carbon dioxide emissions have been significantly increased due to cement production. Alternative low-carbon binders rather than cement have been progressively sought in recent years. Fly ash was found as an available option, since it is being largely disposed annually as a waste material. In this research several studies have been reviewed and recent applications of fly ash on concrete specification, including strength and fracture toughness of green concrete have been perused. Furthermore, transport properties of high volume fly ash after exposure to high temperature and influence of curing temperature on strength development of fly ash-recycled concrete aggregate blends have been investigated. The investigated test results showed that the properties of composites incorporating fly ash depend on the age of the concrete. Test results also revealed that transport properties of concrete increased notably after exposure to 400cº and the results achieved on fly ash-recycled concrete aggregate led to the conclusion that 15% FA is the optimum blend for road stabilization applications.

Open access