Jorge C. Pais, António Ferreira, Caio Santos, Paulo Pereira and Davide Lo Presti
The use of crumb rubber in the modification of asphalt has occurred because of the problems related to disposal of scrap tires. However, the use of scrap tires in asphalt pavements, known as asphalt rubber pavements, can minimize environmental impacts and maximize conservation of natural resources. The textile fibers from recycled tires are typically disposed of in landfills or used in energetic valorization, but similar to other fibers, they can be used as a valuable resource in the reinforcement of engineering materials such as asphalt mixtures. Thus, this work aims at studying the use of textile fibers recycled from ground tires in the reinforcement of conventional asphalt mixtures. The application of textile fibers from ground tires was evaluated through laboratory tests on specimens extracted from slabs produced in the laboratory. Indirect tensile tests were performed on a series of nine asphalt mixtures with different fiber and asphalt contents and compared with a conventional mixture. The results obtained from a 50/70 pen asphalt were used to define three asphalt mixture configurations to be used with 35/50 pen asphalt. The results indicate that the textile fibers recycled from used tires can be a valuable resource in the reinforcement of asphalt mixtures.
In the paper, the backwater curve ranges at the mouth of the Odra River with changing boundary conditions were analysed. The aim of the study is to determine which boundary condition, i.e. stage of lower cross-section or flow in upper cross-section, has a greater impact on the formation of the backwater curve at the mouth of the Odra River. Due to the complicated system of the Lower Odra River network (Międzyodrze and Dabie Lake), the analysis takes into consideration a section of the Odra River from a weir in Widuchowa upwards, thereby accepting as an axiom that the cross-section in Widuchowa is within the range of sea impact, regardless of other hydrological conditions.
Mass movements and floods are natural hazards posing a threat to the environment and bring significant economic losses. The flooding and landslide are risks in the municipalities of south-eastern Poland. Long-lasting rains cause initialize process of landslides on the slopes above the river valley, as well as flooding of local infrastructures (buildings, roads, railway tracks) located near water courses. Monitoring of geotechnical and hydrological parameters of the area is the base for the prognosis, as well as the risk assessment associated with them. So, in the paper highlights the issue of the consistency of monitoring and warning systems for these two threats. For landslides work SOPO - System Guards Against Landslides. Hydrogeological bases are defined for floodplains as The Computer System of the National Guard - ISOK. However, notable is the lack of integrity of both systems. In this paper a proposal to determine the overall risk for both threats in case of a single building is presented.
The oldest man-made false-arch stone bridges are presented and briefly described. It is shown that this construction technique was based on the experiences of the first builders, formed at the junction of ancient Egyptian, Mycenaean as well as Assyrian and Babylonian cultures. Arches in such bridges have not yet been constructed in a classical manner, i.e. one that was later prevalent by the Romans, but these were only the primitive arch-like structures, with a false needle vault, that were shaped mainly by corbelling. This type of the structure, if it was used in bridges, turned out to be much more stable than the well-known at that time and commonly used in gateway passages oval “true-arch” built from sun-dried mud bricks.
For new railway bridges with small spans (L ≤ 35.00 m) superstructures with steel beams embedded in concrete are recommended and used, which can ensure the requirements of strength and especially stiffness, regardless of velocity.
In all the design prescriptions used so far for superstructures with steel beams embedded in concrete, and even in the technical literature, there is little information and data on the influence of the support line obliquity and the track axis curvature in the design and calculation of these types of structures.
In the design code, if certain conditions related to the geometry of the superstructure are met (obliquity, curvature) the calculation is a simplified one, made on a single isolated longitudinal beam of the deck; otherwise, if the conditions are not met, finite element program analysis is recommended.
The article aims to study the situations in which the requirements of the design prescriptions are not met.
The article describes the results of tests carried out to determine the measurable effect of vibrations on the accuracy of measurements with an automatic precise leveller. It contains specification of the research station created to examine the case and description of factors affecting the measurement results. The multi-frequency vibrations were forced on a leveller during measurements and calculated mean errors for each frequency analysed. The range of frequencies for which the measurement was possible was estimated. The obtained results can be helpful in the engineering measurements designing, especially in industrial areas, where vibrations are an inseparable element of the environment.
Traian Mazilu, Ionuţ Radu Răcănel and George Stoicescu
The rail dampers are mechanical devices which work as dynamic absorbers to reduce the rail vibration and rolling noise. The paper shows the experimental results from the functionality and performance testing of an experimental demonstrative rail damper. The vibration attenuation takes the highest values, namely 6-22 dB, between 160 and 1000 Hz.
Unaesthetic stains and deposits often form on external facades (especially those facing the north) in places where barriers were installed on them. Such places include, for example: fragments of facades in which external window sills were mounted, canopies, downspouts, boxes, advertising billboards, flags holders, lightning conductors, aerials as well as facade steps, and many others. During exploitation, elevations are exposed to water retention. In places were barriers are installed, moisture occurs with greater intensity than in other parts of the facade. Over time, in addition to the aesthetic problem, this results in biodeterioration (biological corrosion), induced by the deposited biological factors. The article presents the issue of placing barriers on external facades, on the example of buildings developed in Zielona Góra.
Ewelina Płuciennik-Koropczuk and Patrycja Kumanowska
The article presents the results of research on changes in selected water parameters during distribution in the water supply network of the city of 22 thousand inhabitants. Water parameters were controlled at 8 points in the network, distant from Water Treatment Plant from 0.4 to 3.1 km. The location of control points was selected in order to assess the water quality depending on the pipe material and at unfavourable points - at the ends of the network. It was shown that as a result of secondary water contamination an increase in turbidity, colour and total iron occurred. The distance from the Water Treatment Plant and the type of material of the network or connection, affect the quality of the water. It was confirmed that at the ends of the network the water parameters were increased and exceeded the admissible values.
Maciej Szumigała, Agnieszka Pełka-Sawenko, Tomasz Wróblewski and Małgorzata Abramowicz
The paper presents analysis results of steel-concrete composite beams, identification and attempts to detect damage introduced in a discrete model. Analysis of damage detection was conducted using DDL (Damage, Detection, Localization), our own original algorithm. Changes of dynamic and static parameters of the model were analysed in damage detection. Discrete wavelet transform was used for damage localization in the model. Prior to ultimate analysis, two-tier identification of discrete model parameters based on experimental data was made. In identification procedure, computational software (Python, Abaqus, Matlab) was connected in automated optimization loops. Results positively verified the original DDL algorithm for damage detection in steel-concrete composite beams, which enables further analysis using experimental data.