| Summary: |
This project will initiate with improvements to the existing computational program, in terms of its capacities for running dynamic analyses considering the bridge-train interaction. Consequently, it is envisaged that the algorithm of dynamic interaction is extended to structures modelled by shell and volume
elements, the performance of the program is enhanced in terms of calculation times, the library of high speed train models is enlarged with 3D models and with trains of regular type, and implement alternative ways of defining the wheel-rail interface irregularities.
Simultaneously, a set of computational routines will be implemented for the assessment of the structural behaviour of railway bridges. In terms of fatigue, methodologies based on fracture mechanics concepts or on non-linear damage accumulation will be employed. In what respects track safety, new criteria regarding the acceleration of the deck will be implemented to account for the stability of the ballast, recently proposed as an alternative to those indicated in EN1990-A2. In terms of passengers comfort, procedures for its evaluation will be installed based on the
criteria present in ISO2631 standard, in the report of the D190 committee of ERRI, in the UIC 513 sheet and also in ENV 12299:1999. These involve the quantification of comfort indexes based on pondered values of the accelerations at the carriages, as an alternative to EN1991-2 proposal which only takes into account the peak values of this parameter.
The improved dynamic analysis tool and the new assessment methodologies of the structural behaviour will be applied in numerical studies of bridges located in modernized sections of the National railway network and in European high speed railway lines for the traffic of high speed trains. The dynamic behaviour of the bridges will be assessed for the traffic of real high speed trains and for the loading schemes corresponding to the High Speed Load Model, in order to account for the int  |
Summary
This project will initiate with improvements to the existing computational program, in terms of its capacities for running dynamic analyses considering the bridge-train interaction. Consequently, it is envisaged that the algorithm of dynamic interaction is extended to structures modelled by shell and volume
elements, the performance of the program is enhanced in terms of calculation times, the library of high speed train models is enlarged with 3D models and with trains of regular type, and implement alternative ways of defining the wheel-rail interface irregularities.
Simultaneously, a set of computational routines will be implemented for the assessment of the structural behaviour of railway bridges. In terms of fatigue, methodologies based on fracture mechanics concepts or on non-linear damage accumulation will be employed. In what respects track safety, new criteria regarding the acceleration of the deck will be implemented to account for the stability of the ballast, recently proposed as an alternative to those indicated in EN1990-A2. In terms of passengers comfort, procedures for its evaluation will be installed based on the
criteria present in ISO2631 standard, in the report of the D190 committee of ERRI, in the UIC 513 sheet and also in ENV 12299:1999. These involve the quantification of comfort indexes based on pondered values of the accelerations at the carriages, as an alternative to EN1991-2 proposal which only takes into account the peak values of this parameter.
The improved dynamic analysis tool and the new assessment methodologies of the structural behaviour will be applied in numerical studies of bridges located in modernized sections of the National railway network and in European high speed railway lines for the traffic of high speed trains. The dynamic behaviour of the bridges will be assessed for the traffic of real high speed trains and for the loading schemes corresponding to the High Speed Load Model, in order to account for the interoperability demands established for the European high speed railway network.
The numerical studies will be articulated with the experimental studies carried out in bridges located at modernized sections of the National railway network. The environmental vibration tests will provide information regarding the dynamic properties of the structure. The controlled traffic dynamic tests will enable to obtain the dynamic responses of the bridge-train system in known traffic conditions. The results of these tests will be used for updating and validating the developed numerical models.
In addition, the dynamic measurement system will be operating for relatively long periods of time, providing information about the real effects induced by traffic on the structure, namely in terms of the levels of structural and track safety, estimates of the fatigue damages on the different elements, with special interest to the maintenance of structures, and estimates of the residual life of
these structures.
The numerical studies of deterministic nature will be complemented with studies using a probabilistic approach to the assessment of the dynamic behaviour of bridges, which will take into account the random character of factors related with the bridge, wheelrail interface, traffic and other loads that may occur simultaneously with the traffic loads.
These studies will involve stochastic simulations of the dynamic response of the bridge-train system, based on the Monte Carlo or the Latin Hypercube methods, as well as the assessment of the structural reliability of the case study bridges with respect to structural safety limit states (dynamic amplifications and fatigue), track safety limit states, related with the vertical acceleration, torsion and rotation at the edges of the deck, and to the passengers comfort limit state. |