Papers by Keyword: Reconstruction

Abstract: The paper presents experimental and computer researches of ferroconcrete beams at high-temperature influences. There were conducted the experimental fire tests of ferroconcrete beams. The most promising way of verifying these experimental research data is computer simulation of structures, also during a fire. In order to evaluate the quality of the experiment and the reliability of the received temperature distribution.

Abstract: The paper presents the execution of repair works of the movable bridge conducted by Spegra, a company specialized in the restoration and reconstruction of various types of structures. The Trogir - Čiovo Island bridge is located on the Croatian coast near the historic city of Trogir. The bridge spans a narrow sea strait, connecting the city of Trogir with the nearby Čiovo Island. It was built in 1962 as a movable bridge with a structure consisting of steel and reinforced concrete elements with a stone cladding. The bridge has three spans, with a total length of 102 meters including approaches. The central movable span structure is an arch steel construction, while the other two are reinforced concrete arches. The bridge restoration works are divided into three groups. The first group: dismantling, restoration, and assembly of the steel span structure and expansion joint steel elements. The second group: restoration of reinforced concrete elements: roadway slabs, pedestrian walkways, arches, and the interior of caissons. The third group: restoration of the stone cladding of the bridge. All works were conducted in cooperation with the Conservation Department of the city of Trogir.

Abstract: The paper critically discusses the issue of reconstruction of a historic wooden structure carried out as part of the process of protection and interpretation of a place of special historical importance. The problem is presented on the example of historic log cabins located in the Tennessee state in the USA. These are the following architectural objects: the Cabin at the Meriwether Lewis Monument, the architectural complex in Wynnewood and The Historic Sam Davis Home and Plantation. The presented case studies contribute to the analysis of the horizon of authenticity both the reconstructed architectural structures and the historical sites in which they are located.

Abstract: The paper presents a structural survey of the arch bridge from the 17^th century located in Portz Insel near Mikulov. The purpose of the research was to analyze service life and reliability of the bridge structure including long-term functional durability. There were performed probes in order to search for the original frame foundation and defining a shape of particular arches buried in the ground for decades. The probes also helped to check up the structure of the bridge deck in several places. Currently, throughout 2019 and 2020, the bridge will undergo major reconstruction work in the context of the project „Mikulov, Portz Insel – restructuralisation of the historic countryside“.

Abstract: The publication outlines the issue of the experimental determination of modal parameters of structures using a method called operational modal analysis. The principle of the method and possible approaches of calculation of modal parameters are presented. An example of the method’s application is the determination of mode shapes and frequencies of the repaired footbridge in Kroměříž where the dynamic test was performed twice – before and after reinforcement of the structure. The results of both dynamic tests and their comparisons with the results of the calculation model performed in the ANSYS environment are presented in this article. Additionally, and integral to this article is a description of the completed footbridge reconstruction.

Abstract: The present studies provided for an improvement in the technology of applying protective coatings for metal building structures, primarily coatings being renewed during their repair, modernization or reconstruction of production. At that the main objectives of the research were reduction of the labor coefficient of work relating to the preparation of surfaces of metal building structures, by applying the rust painting method, and creation of anticorrosive materials with universal properties combining the functions of rust, primer and basic coating modifiers.

Abstract: The paper focuses on the analysis of reconstruction in terms of CO₂ concentration. The reconstruction at the university included the exchange of windows. The original windows were exchanged for the modern wood tight windows. Providing CO₂ concentration in the interiors of a university is immensely important for the students of the university. Not exceeding CO₂ concentration limits is necessary not only for the physiological needs of students but also for the required performance of students. Teaching is conducted during the whole day in the researched university schoolroom. The short-term natural ventilation during the breaks is noticeably not sufficient. After 15 minutes from the beginning of the lesson, students started complaining about the air quality and they had to open the windows. To point out the unsustainable state of the poor air quality during the day-long teaching and to be able to prove the officials the importance of the continuation of the reconstruction by building mechanical ventilation or air conditioning system, there were carried out the experimental measurements in the schoolroom. The device Testo 480 was used for the measurements. Obtained values of CO₂ concentration are presented in the charts. Interestingly, this reconstruction significantly decreased the air quality. The admissible values of CO₂ concentration were exceeded after the first hours of teaching. These values were worsening with each additional hour of teaching. Therefore, another reconstruction is needed to enable the transition from natural ventilation to the mechanical ventilation system. In the conclusion of this paper, there are principles how to design new schoolrooms. Furthermore, there are presented recommendations how to operate the existing schoolrooms.

Abstract: The paper deals with the properties, quality and durability of the exposed concrete. The main part of this paper are characteristic of architectural (sometimes called visible or naked) concrete and the criterion of the quality evaluation of the performed work. This is mainly the colour balance of the subject area, the quantity and the size of the pores, the quality of the raw material and the surface structure. Achieving the quality of architectural concrete is considerably more technologically demanding compared with conventional concrete. This is reflected also in its cost. In conclusion, the problems of surface layers of architectural concrete are summarized. Especially environments can cause faster degradation, reducing the lifetime of the whole construction, but also pointing to one of the main problems in construction, which is technological discipline.

Abstract: High productivity of rolling and pipe rolling mills, good quality of finished metal products is possible to provide in the presence of powerful heating furnaces, well heating the metal with minimal oxidation and decarburization. Such conditions are provided by ring furnaces which are widely used for heating the preparations at rolling of pipes, wheels and bands of the railway rolling stock. The purpose of the heat – receiving structure of the metal, providing a set of physical and working properties, or impart to these materials the ductility required for subsequent machining. The article deals with the design and thermal performance of the ring furnace operating at ChelPipe’s Pipe Rolling Plant No.2. The problems arising during the operation of the thermal unit are analyzed. The paper describes the calculation of heating of metal and heat balance of the ring furnace. In the course of the analysis of the results of design studies, the shortcomings of the existing heat recovery system are revealed and measures for the reconstruction of the furnace to reduce fuel consumption and increase productivity (replacement of the existing brick lining with fibrous, the use of regenerative burners, the use of non-water-cooled partitions, etc.) are proposed. The paper analyzes the design and thermal performance of the ring furnace for heating of pipe billets before rolling. It shows a heat balance of the ring heating furnace and provides measures for furnace reconstruction aimed at reduction in fuel consumption and increase in efficiency: replacement of the existing lining with fiber lining, use of regenerative burners, application of non-water cooled walls.

Abstract: The paper presents a developed method for assessment of gas distribution over the cross section of a shaft furnace working in the countercurrent conditions. This method is scientifically based on the fundamental principles of the countercurrent heat exchange theory in shaft furnaces, i.e. dependences of the temperature field throughout the burden bed height on the ratio between heat capacities of gas and burden flows. The ratio between the gas flow heat capacity and burden flow heat capacity at the stock line level is determined by the averaged gas temperature at the burden bed output. By comparing these data, we estimated directions for improving the gas distributing system. Efficiency of this method was assessed when analyzing the system of air supply to the shaft furnace at one of the Ural plants. The analysis showed the main drawbacks of the existing gas distributing system and enabled to determine the main directions for reconstruction of this system. On the basis of the analysis results related to operation of the tuyeres and distribution manifold, we proposed more efficient options of their parameters, i.e. manifold cross-section area, tuyere number and diameter, angle of tuyere inclination to the horizontal. These changes provided a uniform distribution of gases across the furnace and improved conditions for melt flow in the furnace. Thus, we established virtually equal conditions for development of heat and mass transfer processes in the work space of the shaft furnace. The modernized system of air supply to MMSK’s shaft furnace increased the furnace performance by 14.14% in terms of burden, by 23.27% in terms of matte, by 15.15% in terms of slag and by 6.65% in terms of thermal efficiency. At the same time, the following parameters were reduced: specific fuel consumption (anthracite) by 17.46% and dust discharge by 40.5%. When supplying air to the furnace through the inclined tuyeres, it became possible to reduce formation of accretions and provide new working conditions for operating personnel due to a more uniform gas distribution across the horizontal section of the furnace. Within six months of furnace operation the personnel had no problems related to its operation.