Papers by Keyword: Load-Carrying Capacity

Abstract: The paper deals with diagnostics, recalculation, and determination of the current load capacity of three concrete arch bridges on the original railway line Bratislava - Žilina. This was built in 1954 in connection with the relocation of the line, caused by the exhibition of the Nosice reservoir. At present, the railway line has been relocated to a new location and the existing original line, including the existing engineering facilities, will be used for the construction of a new road connecting the district towns of Púchov and Považská Bystrica. The task was solved within the cooperation of Faculty of Civil Engineering with the Railways of the Slovak Republic (ŽSR in Slovak) and the Research and Development Institute of Railways (VVÚŽ in Slovak). The conclusions from the recalculations and the subsequently determined load capacity show that the bridge structures in question are suitable for further use, however, their reconstruction is necessary.

Abstract: The paper is focused on diagnostics and calculation of load-carrying capacity of the two atypical girder bridge objects on the railway line between Púchov and Považská Bystrica in Slovakia. These are skewness reinforced concrete (RC) girder bridges with three girders. The non-typicality is given by the fact that the spandrel girders are in the longitudinal direction, but the middle girder is relatively wide and is perpendicular to the clearance (not in the longitudinal direction). The diagnostics was performed on the objects aimed at determining the material and geometric characteristics, which served as a basis for the numerical model. A 3D scanner was also used to determine the geometric dimensions. The load-carrying capacity was subsequently determined on the bridges. The recalculation and diagnostics revealed the fact that bridge structures can still be used, but have to be reconstructed. This is a prime example of reusing in practice, i.e. how the old bridges can be further used, which means a significant saving of CO₂ emission that would be produced by demolishing the old bridges and building new ones

Abstract: This study involved an experimental investigation of the hydrodynamic lubrication performance of dimpled seal-like thrust bearings. Circular dimples were created on lubricating surfaces and the hydrodynamic effects were evaluated. The load-carrying capacity and frictional torque were measured under a constant film thickness. The lubricating surface was observed to make clear the effect of the cavitation area on the load-carrying capacity and the frictional torque. Dimpled specimen produced the load-carrying capacity and it showed a signature hysteresis phenomenon. Cavitation strongly affected the phenomenon. In addition, the dimpled specimen could reduce the frictional torque compared with the plane (dimple-free) specimen. However, the hysteresis phenomenon of the frictional torque was not clear compared with that of the load-carrying capacity.

Abstract: Influence of roughness on conventional hydrodynamic lubrication of tilted pad thrust slider bearing is studied. Roughness effect is studied using Christensen stochastic process. To study the effect of roughness, bearing characteristics like load carrying capacity is analyzed.

Abstract: The handbook "Determination of load-carrying capacity of railway bridges" [1] has grown up due to updating of old Slovak guideline [2] taking into account Eurocodes. In the case of railway bridges, there are about 2300 bridges in Slovakia and about 78 % of them are from concrete or masonry. About 28 % of bridge total number is older than 77 years and about 18 % of them are even older than 100 years. Therefore, there is need to make regular inspections, recalculate them – determine of load-carrying capacity and then to decide, which of them should be repaired or reconstructed [3,4]. The paper presents general concepts and basic assumptions for determining the load-carrying capacity of reinforced and prestressed concrete railway bridges. In contrast to design of a new bridge, additional data related to existing bridge condition and its behaviour like information from regular inspections and real state of degradation can be taken into account. Special recommendation and allowances for global analysis of existing concrete superstructures for the purpose of the load-carrying capacity estimation are discussed, as well.

Abstract: In the frame of global European standardization and in consequence of new knowledge related to existing bridges, the need for revision of the service handbook "Determination of load-carrying capacity of railway bridges" grown up. The paper presents general concepts and basic assumptions for determining the railway bridge load-carrying capacity. In contrast to design of a new bridge, additional data related to existing bridge condition and behavior like information from regular inspections and real state of degradation can be taken into account. Based on these data together with the remaining lifetime, a modification of reliability levels for existing bridges based on the mathematic theory of probability can be adopted in the evaluation process. Special attention is also paid to the specific features of determination of load caring capacity of steel-concrete composite bridges in exploitation. Recommendation and allowances for global analysis of existing composite steel and concrete superstructures for the purpose of the load-carrying capacity estimation are discussed as well.

Abstract: Mechanical property and constraint mechanism of concrete cylinders confined by TRC under uniaxial compression is analyzed. 24 concrete cylinders confined by TRC and 8 unconfined concrete cylinders are loaded under uniaxial compression to investigate the performance based on textile ratio, section dimension and strength of concrete. Based on the test results, stress process and failure mechanism of strengthened members is studied, stress-strain relationship of strengthened members is researched, effect of ratio of textile reinforcement, section dimension and concrete strength on ultimate strength of strengthened members is also evaluated. The results show strengthened members showed increasing in strength and deformation. Strengthened members showed drum-shaped shear damage. With the increasing of textile ratio, the confining effect of TRC on the concrete increases. With the increasing of section dimension, the confining effect of TRC on the concrete decreases. The confining effect of TRC on low strength concrete is stronger.

Abstract: In order to study the differences in load-carrying capacity of surface-textured soft materials and stiff materials, a theoretical hydrodynamic model considering elastic deformation is developed for numerical simulation analysis. Minimum oil film thickness at a certain load is computed as an index to evaluate the load-carrying capacity of textured sliding surfaces made of soft materials and stiff materials. The results show that the elastic modulus affects greatly on the load-carrying capacity. In the case of the surface texture with a dimple aspect of 0.05, textured soft materials has a higher load-carrying capacity than that of the stiff materials. In the case of the surface texture with a dimple aspect of 0.01 and only under high loads, textured stiff materials provides a better load-carrying capacity than that of the soft materials.

Abstract: The formed rivet head was measured in order to verify rivet closing-up forcein the executed riveted joint. The measurements were performed using two specimen series with strapped joint. The first series of specimens was prepared using standard riveting technology: drilling and reaming of holes and kinematic heading of rivets. In the second series of specimens modified technology was used: drilling, sizing and heading of rivets with controlled heading force.The relationship of the formed rivet head diameter on the heading force was determined. For that purpose tests with controlled heading force were performed and the formed rivet head diameter for each force was measured. The limits of formed rivet head diameter for the second series of specimens, which were headed using controlled heading force were calculated. Based on the scatter of formed rivet head diameters for the first series of specimens the range of forces achieved during kinematic heading of rivets was determined. The riveted joint load-carrying capacity using tension was assumed. Special instrumentation was prepared for riveted joint tests. Achieved joint load-carrying capacity results were collated with specific heading forces for the first series of specimens. Based on the heading force values put on the load-carrying capacity diagram was concluded that kinematic heading does not guarantee achievement of the optimum load-carrying capacity.

Abstract: To carry out of out-of-plane stability analysis of plane tubular trusses, nonlinear finite elements model based on spatial beam elements and simplified connection elements is deduced. To verifying the feasibility of the simplified joints stiffness model, numerical examples are build and results shows that the simplified finite elements model is comparatively accurate , and could be used in engineering design.