Measurement of corrosion rates on reinforcement using the field test

Reinforcement corrosion is a phenomenon that affects not only the durability and serviceability of the structure itself but the economy of the countries, as well. In many cases, structures and bridges must be repaired or reconstructed as a result of corrosion of the reinforcement. In extreme cases, when maintenance is neglected, it is necessary to completely replace the structures with new ones, even if their planned service lifetime has not been reached - it is not enough to strengthen them or it is economically inefficient. Corrosion of the reinforcement primarily causes a reduction in the cross-sectional resistance of the load-bearing elements by reducing the cross-sectional area of the reinforcement, which means a reduction in the force in the reinforcement that it transmits. For this reason, it is necessary to know the rate of corrosion over time depending on the environment in which the element is located. The paper is focused on the experimental measurements of corrosion losses due to atmospheric corrosion on reinforcement samples using the field test. As a part of experimental measurements, corrosion rates on reinforcements of four diameters (diameters 6, 10, 14, and 25 mm) of steel for reinforcement, grade B 500B, are monitored at measuring stations and bridges in various aggressive environments.This research was supported by Research Projects No. 1/0623/21 of the Slovak Grant Agency

Effective computational model for a solution of turbocharger rotor dynamics

The article describes the development and a subsequent application of a computational model for effective and fast simulations of the turbocharger rotordynamics in time domains. The simulation tool consists of two basic models which are described in the article. The rotor is modelled as a flexible structure based on the nonlinear beam approach suitable for an effective solution in the time domain. The computational model also incorporates radial and axial bearing models. Theoretical background of the inovative journal bearing computational models, based on the numerical solution of the Reynolds equation, is presented. The capabilities of the simulation and sample results are demonstrated on a middle size turbocharger rotor supported by fully floating ring bearings

Pinned - Fixed Beam - Column Resistance Verification According to European Standards

Verification of beam-column resistance can be accomplished according to design approaches given in EN 1993-1-1 [1]. These approaches are derived from verification of single span beam with pinned end conditions subjected to compression and bending moments. In the case of different end conditions, the application of those approaches is not so accurate and more difficult. Therefore, the comparison of verification according to above standard EN 1993-1-1 [1] as well as EN 1999-1-1 [2] to results of experimental analyses of beam-columns having pinned-fixed end conditions subjected to an eccentric compressive force simulating the behaviour of columns integrated into frames is presented in this paper

Strengthening of Concrete Column by Using the Wrapper Layer of Fibre Reinforced Concrete

Structures and bridges are being designed on the proposed and requested design lifetime of 50 to 100 years. In practice, one can see that the real lifetime of structures and bridges is shorter in many cases, in some special cases extremely shorter. The reasons for the lifetime shortening can be increased of the load cases (e.g., due to traffic on bridges, or due to other uses of a structure), using the material of lower quality, implementation of new standards and codes according to Eurocode replacing older ones. During the whole lifetime the structures must be maintained to fulfil the code requests. If the constructions are not able to fulfil the Ultimate Limit States (ULS) and the Serviceability Limit State (SLS), the structures or bridges have to be strengthened (whole or its elements). The purpose of the paper is the presentation of using a layer of the fibre concrete for a columns’ strengthening. Using the fibre reinforced concrete (FRC) of higher tensile strength makes it possible to increase the load-bearing capacity of the cross-section the column. The contact between the old concrete (core of column) and newly added layer (around column) is very important for using that method of strengthening. In the article, there is also a comparison of the surface modification methods

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An Experimental and Numerical Analysis of Glued Laminated Beams Strengthened by Pre-Stressed Basalt Fibre-Reinforced Polymer Bars

Damage often develops in glued laminated timber members under high bending loads due to natural defects in the timber, which results in their low load-bearing capacity and stiffness. In order to improve the bending mechanical properties of glulam beams, a new type of longitudinal glulam reinforcement with pre-stressed basalt fibre-reinforced polymer composites (BFRP) was developed using the Near Surface Mounted (NSM) technique. The strengthening method consisted of two pre-stressed BFRP bars glued into the grooves at the bottom side of the beam; meanwhile, for the second strengthening alternative, the third BFRP bar was embedded into the groove at the top side of the beam. Therefore, an experimental study was carried out to verify this strengthening technique, in which fifteen full-size timber beams were tested with and without bonded BFRP bar reinforcement in three series. According to the results of this experimental study, it can be seen that the effective load-bearing capacity of the reinforced beams increased up to 36% and that the stiffness of the beams increased by 23% compared to the unreinforced beams. The tensile stresses in the wooden fibres were reduced by 11.32% and 25.42% on average for the beams reinforced with two and three BFRP bars, respectively. On the other hand, the compressive stresses were reduced by 16.53% and 32.10% compared to the unreinforced beams. The usual failure mode saw the cracking of the wood fibres at the defects, while for some specimens, there were also signs of cracks in the epoxy adhesive bond; however, the crack propagation was, overall, significantly reduced. The numerical calculations also show a good correlation with the experimental results. The difference in the results between the experimental and numerical analysis of the reinforced and unreinforced full-sized beams ranged between 3.63% and 11.45%

Analysis of the Impact and Mechanical Properties of a Damper Made of Hyperelastic Material

The proof-load tests are an integral part of verifying the actual behaviour of bridge objects. If a new bridge object is put into operation after construction, it is necessary to verify whether it will behave as it was supposed to when it was designed. In the case of existing bridge objects, it may happen that the bridge has malfunctions or behaves unconventionally due to failures - then there may be a need to reconstruct and strengthen the bridge object, and thus again there is a need to verify its behaviour using a proof-load test. The proof-load test can be static or dynamic. The aim of the paper is to point out the inevitability of the proof-load tests for the real and correct behaviour of bridge structures in ultimate limit state and maximum allowable deformations in serviceability limit states. It is necessary to point to the greatest consequences of resistance, reliability, durability and lifetime of the bridge structures. Using the proof-load tests for new bridges is prescribed by the Slovak standard STN 73 6209

Calibration of partial safety factors according to Eurocodes

Recommended reliability levels and their adequate partial safety factors can be found in Eurocodes only for design of new structures and bridges. Modified reliability levels and partial safety factors for verifying bridge structures for their remaining lifetime were determined by theory of reliability at Department of Structures and Bridges at Civil Engineering Faculty, University of Žilina. This paper is focused on verification of modified partial safety factors of materials and load effects using calibration

Calibration of partial safety factors according to Eurocodes

Recommended reliability levels and their adequate partial safety factors can be found in Eurocodes only for design of new structures and bridges. Modified reliability levels and partial safety factors for verifying bridge structures for their remaining lifetime were determined by theory of reliability at Department of Structures and Bridges at Civil Engineering Faculty, University of Žilina. This paper is focused on verification of modified partial safety factors of materials and load effects using calibration

Load-Carrying Capacity of Bailey Bridge in Civil Applications

The paper presents an extensive study aimed to determine the applicability of the demountable Bailey bridge (BB) system on construction sites or in other temporary conditions while meeting the regulations for the design and assessment of steel bridges. The analysis is focused on whether and to what extent the BB system with spans between 12 and 36 m is usable for on-site freight transport with conventional lorries with a total weight of up to 22–28 tons. At the same time, the BB system within these spans should be utilized for construction vehicles with a total weight of up to 32–40 tons. To calculate the load-carrying capacity, spatial numerical models were analysed using FEM and procedures of actual design codes were utilized. In the case of the main girders, analysis is focused on the out-of-plane stability of their compressed chords. Recommendations for the use of this bridge system in different arrangements of the main girder and bridge deck are then summarized and discussed