During the railway track life, its operational quality is represented by the key information on the extent and method of its degradation, applying indicators which were appropriately selected, surveyed and evaluated within the diagnostic activities. The paper describes methods and procedures of experimental verification, i. e. obtaining and evaluating operational quality indicators, representing design parameters and determining its quality. Determining the dependence of the values of different quality indicators on time or place of measurement allows to construct models of structure behaviour over its lifetime and to predict the time and place when and where the permissible boundary values of the qualitative indicators can occur. The paper presents the models prepared for monitored experimental sections in the Slovak Railways (ŽSR) network.
An experimental study was proposed to understand the behaviour of single pile in sloping ground with various eccentricity. Cohesionless soil was used for conducting experiments with a horizontal ground and with a slope of 1V:2H. With calculated stiffness factor (T) as 92 mm, the eccentricity was varied as 0T, 0.5T and 1T. The lateral capacity of the pile in horizontal and sloping ground condition decreases with increase in eccentricity; the increase in lateral capacity was linear too. The bending moment increases with increase in load; but the depth of maximum bending moment was 0.15 m for 0T and 0.5T of eccentricity. For 1T of eccentricity, the depth of maximum bending moment varied to 0.07 m from the point of load. An equation was proposed to calculate the maximum bending moment of the pile for any eccentricity for a slope of 1V:2H, which is the governing factor for pile designing.
The present study was conducted to investigating interaction of three types of mixing water (tap water, briny groundwater and a mixture of their equal ratio), four levels of cement substitution with zeolite in the concrete mix design (0 %, 10 %, 20 % and 30 %), two levels of cement content (250 and 350 kg·m−3) and seven curing ages (3, 7, 28, 56, 90, 180 and 365 days) on compressive strength of concrete. In order to statistical analysis of data - a means that was not employed in the similar studies - the study was designed as a factorial experiment based on the completely randomized design with 168 treatments and three replications (totally 504 concrete specimens). The results of the analysis of variance (ANOVA) showed that neither of the two-, three- and four-way interactions of curing age with other factors were not statistically significant. This means that the gain rate of compressive strength of concrete by time was significantly similar in each possible combination of cement content, water type, and zeolite percentage. However, regarding the significant two- and three-way interactions of other studied factors, more attention should be paid to the results of these interactions than the simple effects of factors. Accordingly, based on the means comparison test (least significant difference: LSD), simultaneous use of unconventional waters with zeolite up to 20 % in the cement content 350 kg·m−3 can be recommended in terms of compressive strength of concrete.
Nowadays, the utilization of locally accessible materials is a crucial stage for sustainable, economical building material on the earth’s surface. Within them, brick is one of the commonly used construction materials around Jimma town due to the availability of clayed soil. Nevertheless, brick produced by small micros unskilled enterprises rather than by traditional methods, its quantity was small, and its quality was unsatisfactory because it can easily break, and it has high water-absorbing conduct. The purpose of the investigation was to improve the properties of clayed soil properties by using laterite soil for the manufacturing of bricks for masonry units. In order to achieve this, research used non-probability sampling techniques to collect samples in Jimma area. Then, the collected samples prepared for different laboratory tests and by partially replacing literate soil by 5 %, 10 %, 15 % and 20 % on a clayed soil in order to get optimum property by different mix ratio for different laboratory tests results indicated showed that the lightweight bricks could be made from the approach of this study without any deterioration in the quality of bricks.
Additionally, the compressive strength of the blocks optimum at 15 % lateritic soil replaces in clayed soil contents. The optimum firing temperature furnace at a duration burning of brick was at 1000 °C for 5hrs. It has shown that bricks prepared of clay-laterite earth capable of high resisting capacity rather than for beauty.
In ballasted track, the wheel load is transmitted to the subgrade via sleepers commonly made of impregnated wood, prestressed concrete, steel or recently developed polymer sleepers. Mentioned material types of sleepers are characterized by different elastic moduli being a key parameter in any numerical model. Hence, this paper aims to determine the elastic modulus of sleepers subjected to a laboratory four-point bending test. Traffic resembling load level of 60 kN adopted from a typical axle load distributed by the rails to the sleeper was applied in a quasistatic and cyclic loading. The samples included sleepers made of polymers complemented with wood and pre-stressed concrete. The results of this paper are based on the elastic modulus investigation. Main conclusions are focused on the sleeper’s elastic modulus under changing loading frequencies. Wood and prestressed concrete sleepers indicated mainly elastic behaviour resulting in a constant elastic modulus. However, polymer sleepers showed a loading frequency dependent elastic modulus as a result of their viscous elastic behaviour. Moreover, the conclusions of this paper involve E-modulus measurements of impregnated beech sleepers in order to describe their piece by piece elasticity variation due to their natural origin.
The deterioration common crossing elements increase the need for the maintenance of crossings and significantly reduce the reliability, availability and safety of railway traffic. The present paper introduces the results of experimental investigation of common crossing monitoring while its deterioration during the lifecycle of crossing. The conventional methods of common crossing condition estimation with time-based features like maximal accelerations, etc. are low appropriate as statistically significant condition indicators. The proposed multifractal analysis enables to extract the significant features from acceleration measurements. The extracted features are fused together with information about the train velocities and longitudinal position of wheels impact with the Lasso regularisation and multivariate linear regression. A ranking of feature importance is done and the redundant features are identified. The developed condition indicator has good correlation to the crossing lifetime and is simple for interpretation.
Software ISEH (Integrated system of road projects economic evaluation) evaluates variants of road repair and maintenance technologies. The economic assessment is based on Cost Benefit Analysis indicators (net present value, internal rate of return, pay-back period and cost benefit ratio). According quantified indicators are determined order of repairs and maintenance of assessed road sections. The road works cause additional negative impacts to road users. The road repairs and maintenance create on road so-called work zones, which negative affect road users. One of the negative impacts is travel time loss of road users. The process of quantification and valuation of travel time costs due to road works, i.e. work zones create a base for implementation to the ISEH software. For implementation it was necessary to suggest changes in current algorithm of the Software - Integrated system of road projects economic evaluation. The aim of the implementation is effective planning road repairs and maintenance not only in terms of choice effective technology but also in terms of reducing negative impacts to road users. A practical example of calculating travel time costs due to work zone has been processed in Excel software.
The quality of bituminous binders is commonly evaluated by the empirical tests. The functional approach to the evaluation of bitumen properties is a trend that has been applied in the last years. The dynamic shear rheometer (DSR) test has been widely used to determine the shear complex modulus of bitumen in the wide range of frequencies and temperatures. A lot of research works were focused on the effect of the chemical compounds of bitumen on the values of the shear complex modulus. The missing information related to the effect of the compound of bitumen on the elastic and plastic part of the shear complex modulus was input for the presented investigation. The significant effect on the elastic part of the complex modulus was determined only at the high temperatures (60 and 80 °C). The aromatics, resins and asphaltenes were identified as the influencing compounds. The important effect was also noted for the resins at the temperatures of 5 and 15 °C. It was also concluded that the effect of the saturates on the elastic part of the shear complex modulus is marginal. The effect of the aromatics and asphaltenes on the plastic part of the shear complex modulus was identified only at the temperature of 80 °C. The effect of these two compounds at other temperatures seems to be unimportant. The significant effect of the resins was stated for the temperatures of 15 °C and 5 °C. Their effect at other temperatures can be supposed as marginal. The negligible effect of the saturates on the plastic part of the shear complex modulus was deducted.
The regression analysis of the chemical composition of the bitumen and the parts of the shear complex modulus at the temperature of 80 °C proved that the frequency of the DSR test can be a factor affecting the level of the relationship between the group composition of the bitumen and its rheological properties.
With spreading of population and increasing of instruction, and also because of limited resources and materials, the demand for using novel materials in building industry has increased. The reinforced concrete columns and steel beams are used in structures with composite moment frame (RCS). Use of compression strength in proportion with concrete and bending strength of steel beam has bestowed these structures less weight than that of concrete structures and made it easier to access the measure of strong column - weak beam especially within long span in these structures. The most important part of these structures is connection of steel beam with the reinforced concrete column. These connections are divided into two general groups of connection with bracing beam and with bracing column from the joint. This paper aims to study the seismic behavior and parameters of RCS composite frame composed of steel beams and strong concrete column. The finite element method was analyzed by ABAQUS software and data analyzed by Excel.
The tunneling technologies are constantly evolving, with the large diameter multifunctional city tunnels becoming more and more common. By building tunnels of large diameters in urban areas one can rationally distribute traffic flows within the unified space and combine various modes of transport. However, such scalable transport construction projects imply a serious pressure both on social aspects of the big cities life and on the city environment. So, in order to make a decision one needs to perform a comprehensive analysis. The authors have analyzed the foreign experience in large diameter tunneling to assess whether it is viable to use these kinds of structures under the geological conditions of St. Petersburg.