ABSTRACT
The main purpose of this paper is to present some results concerning the investigation of the
effects of the vehicle-bridge interaction in simply supported medium span viaducts, including
the modelling of the ballast-rail track system. This system is modelled using the rail stiffness
in vertical and longitudinal directions, including the rail pad and the sleepers, and the ballast
as a system of vertical springs, dampers and masses. A simplified vehicle model proposed by
the European Railway Research Institute (ERRI D214, 1999), taking into account the vehicle
primary suspension characteristics and the mass of the bogie is used with the contact
algorithm implemented in the software ADINA to evaluate the response acceleration of a
simply supported medium span concrete viaduct. The results are compared with those from
the moving loads model for a wide range of train speeds.
INTRODUCTION
Due to the increasing interest in the high speed railway transportation, the research on the
vibration of bridges under moving vehicles has been growing much then ever. The
investigation started to be analytical, with approximate solutions for some simple but
fundamental problems (for example, Fryba, 1999, Biggs, 1964). Nowadays, the investigation
use more realistic and complex bridge and vehicle models to analyse the bridge vibrations
(Yang et al, 2004, Xia 2003). However, in these works, the effects of the ballasted tracks were
only partially accounted for, or they have been completely neglected.
DYNAMIC MODELS OF THE RAILWAY BALLASTED TRACK
The railway ballasted track model is made of several elements which represent the rails, the
sleepers, the connections between rails and sleepers, and the ballast. The rails are an important
component in the track structure, since they transfer the wheel loads and distribute them over
the sleepers and supports, guide the wheels in the lateral direction, provide a smooth running
surface and distribute acceleration and braking forces over the supports. In Europe the typical
rail used in the high speeds lines is the flat-bottom rail, UIC60.
The connections rail/sleeper are materialized by fastenings and rail pads. This system
provides the transfer of the rail forces to the sleepers, damps the vibrations and impacts
caused by the moving traffic and retains the track gauge and rail inclination within certain
tolerances.
THE INTERACTION MODELLING USING ADINA
In the present study, only plane models are considered. The vertical displacements of the
railway vehicles are analyzed and the two rails are effectively treated as a single one in the
subsequent analysis. Figure 4 shows a typical vehicle element with a 2-DOF acting on the
bridge/track system. The upper and lower beam elements modeling the rail and the bridge
deck respectively are interconnected by the rail track model as mention before. Since the high
speed train ICE2 is considered for the analysis, it must be assumed that there are 56 moving
vehicles in direct contact with the bridge or with the platform that must be modeled before
and after the bridge itself.
The main purpose of this paper is to present some results concerning the investigation of the
effects of the vehicle-bridge interaction in simply supported medium span viaducts, including
the modelling of the ballast-rail track system. This system is modelled using the rail stiffness
in vertical and longitudinal directions, including the rail pad and the sleepers, and the ballast
as a system of vertical springs, dampers and masses. A simplified vehicle model proposed by
the European Railway Research Institute (ERRI D214, 1999), taking into account the vehicle
primary suspension characteristics and the mass of the bogie is used with the contact
algorithm implemented in the software ADINA to evaluate the response acceleration of a
simply supported medium span concrete viaduct. The results are compared with those from
the moving loads model for a wide range of train speeds.
INTRODUCTION
Due to the increasing interest in the high speed railway transportation, the research on the
vibration of bridges under moving vehicles has been growing much then ever. The
investigation started to be analytical, with approximate solutions for some simple but
fundamental problems (for example, Fryba, 1999, Biggs, 1964). Nowadays, the investigation
use more realistic and complex bridge and vehicle models to analyse the bridge vibrations
(Yang et al, 2004, Xia 2003). However, in these works, the effects of the ballasted tracks were
only partially accounted for, or they have been completely neglected.
DYNAMIC MODELS OF THE RAILWAY BALLASTED TRACK
The railway ballasted track model is made of several elements which represent the rails, the
sleepers, the connections between rails and sleepers, and the ballast. The rails are an important
component in the track structure, since they transfer the wheel loads and distribute them over
the sleepers and supports, guide the wheels in the lateral direction, provide a smooth running
surface and distribute acceleration and braking forces over the supports. In Europe the typical
rail used in the high speeds lines is the flat-bottom rail, UIC60.
The connections rail/sleeper are materialized by fastenings and rail pads. This system
provides the transfer of the rail forces to the sleepers, damps the vibrations and impacts
caused by the moving traffic and retains the track gauge and rail inclination within certain
tolerances.
THE INTERACTION MODELLING USING ADINA
In the present study, only plane models are considered. The vertical displacements of the
railway vehicles are analyzed and the two rails are effectively treated as a single one in the
subsequent analysis. Figure 4 shows a typical vehicle element with a 2-DOF acting on the
bridge/track system. The upper and lower beam elements modeling the rail and the bridge
deck respectively are interconnected by the rail track model as mention before. Since the high
speed train ICE2 is considered for the analysis, it must be assumed that there are 56 moving
vehicles in direct contact with the bridge or with the platform that must be modeled before
and after the bridge itself.
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