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The railway bridge over the Velika Morava River is located on the Belgrade – Nis main railway line, Gilje – Cuprija – Paracin section. It is a double-track bridge with track laid on crushed-stone ballast. The bridge over the Velika Morava River has five spans. The bridge structure is a steel truss continuous beam, with spans: 52.5 + 67.5 + 82.5 + 67.5 + 52.5, in the total length of 322.5 m. Truss structure height is constant (8.0 m), and the truss width is 10.0 m. Truss consists of diagonal members, without vertical members. All truss members are of box cross-section. Metal sheet is 12 - 36 mm wide. Steel grade is S 235 J2G3 for less stressed members and S 355 J2G3 for highly stressed members in the area of supports and in the middle of the bridge. The Bridge deck is orthotropic deck with longitudinal trapezoidal stiffeners and cross girders spaced at 3.75 m. The bridge structure is completely welded, only steel connections of cross girders and joints of bottom and top bracings are made with 10.9 high-strength bolts applying full tightening force. Bridge bearings are of neoprene (pot bearings). Piers are founded on HW piles, Ø1500, 34 m maximum length. The structure is assembled on embankment (in front of the bridge) and successively longitudinally launched over piers without use of auxiliary trestle. The bridge was completed and put into service in 2016. [ABSTRACT FROM AUTHOR]

Most structures and components are fabricated using welded joints. A very high percentage of all fatigue failures locally occur at welded locations due to high tensile residual stresses and stress concentrations resulting from the weld process. High frequency mechanical impact (HFMI) treatment has been increasingly used as an effective post-weld treatment technique to improve fatigue strength of welded structures. Fatigue tests have been conducted for as-welded and HFMI treated 5083-H321 grade aluminum and ASTM A514 steel welded specimens to investigate the effects of the HFMI treatment under constant amplitude R = 0.1 and variable amplitude loading. This paper presents fatigue test results including local properties (residual stresses) of welded specimens under the as-welded and the HFMI treated conditions. Test results showed that the HFMI treatment significantly improved fatigue life performance of the aluminum and steel welded specimens under both constant and variable amplitude load conditions. Therefore, the HFMI treatment is a quite promising post-weld treatment technique and its potential applications on the fatigue design of welded structures and components can lead to lighter structures and products, in which components and structures can be down-sized and optimized to reduce weights. [ABSTRACT FROM AUTHOR]

Abstract: The calculation methods for assessing the fatigue life of welded structures are gaining increasing importance in many technical applications, since they contribute in the decrease of the development costs and time. In various engineering applications, especially in the commercial vehicle sector with thick and thin components and welds of complex geometry and loading configurations, there is still a lack of experimentally verified guidelines for the calculation of fatigue life. The present paper shows an advanced procedure for FE modeling and fatigue life calculation of welds based on the Notch Strain Approach. It uses elastic-plastic cyclic material properties and can be applied in early stages of development when prototypes are not available. It can be applied to continuous and non-continuous welds, e.g. ones with pronounced terminations. Due to its local character, it covers both weld toe and root failures. To verify its accuracy, the proposed calculation procedure is applied to serial motor truck's rear axles providing complex 3D weld geometries subjected to cyclic loading. Calculated lifetime results are compared to experimental ones determined on a test rig. The agreement is satisfactory. [Copyright &y& Elsevier]

Abstract: Nuclear power plant piping may be submitted to High Cycle Thermal Fatigue phenomenon in mixing zones. French nuclear engineers have at their disposal a simplified approach for assessing the sensibility of the areas with regard to this kind of damage. The engineering tools are quite complex since they involve multi-disciplinary physic phenomena: thermal-hydraulics, mechanics and materials. The results are only qualitative and globally conservative, and this method is only used to identify and to classify the mixing zones which could present a risk. In this framework, this paper proposes to perform a more realistic application of this engineering method on the particular case of the FATHER experiment. The idea is to compare the numerical prediction results with the expertises performed on the FATHER mock-up. Some generic engineering issues raised by nuclear fatigue analyses are here illustrated by the sensitivity analyses which have been performed. The determination of the fatigue loading and the choice of the material criterion are particularly discussed since they are very significant parameters in the analysis. [Copyright &y& Elsevier]

Abstract: A recently more used method of improving weld quality at the weld transition to the plate called HFMI (High Frequency Mechanical Impact) has been investigated and tried on two demonstrators, a bogie beam in an articulated hauler and a dipper arm in an excavator, see fig. 1. The designs of the beams have been made so that thinner plates can be used and higher material strength can be utilized. Such an approach needs to make use of local based analysis methods and in this case the effective notch method was used. Recently made research has suggested SN-curves where the use of HFMI in combination with different material yield strengths are described and these FAT values have been used to develop allowed stress levels in the beams to fulfill the life requirements. All this resulted in components which were 24% and 18% lighter using plate thicknesses of 8-12mm in material yield 700MPa. They were then produced and tested in a rig to verify the designs. The results imply that the HFMI treatment is a very promising method to build lighter welded structures, however, the design needs to take some new considerations into account to succeed. [Copyright &y& Elsevier]

Abstract: Submarine hulls and offshore structures are subject to cyclic stresses in sea-water, and data on crack growth rates are required for predicting the lives of such structures. The corrosion-fatigue crack growth rate of a cathodically protected, high-strength lowalloy steel weld metal (yield strength 700–900 MPa) has been measured as a function of cycle frequency at several constant values. The fatigue crack growth rates increase in a sigmoidal fashion with increasing rise-time of the load cycles, with (i) the inflection points of the sigmoidal curves for different all falling on a common line, and (ii) the gradient at the inflection points having the same value for each . Previously published models for predicting effects of cycle frequency on crack growth rates do not properly account for the data. A new model, based on synergistic interactions between the environment and deformation during loading, has been formulated. The new model, which has some elements of previous models, produces a good fit to the experimental data, not only for the weld metal but also for other steels of similar strengths. [Copyright &y& Elsevier]