Based on the same coupled formulation of the vehicle-bridge dynamic system, written in total displacements and including the effect of the pavement roughness profile, two numerical iterative procedures, named WTH and STS, were previously derived, relying on the same forced uncoupling of the equations of motion. The uncoupled formulation is characterised by time-independent, symmetric matrices. A sufficient generality in the modelling of the two subsystems is retained. A numerical model, not restricted to a particular choice of the adopted elements, describes the bridge; the vehicle is modelled as a multi-body system. Since, in general, the contact points do not coincide with a mesh node, a constraint equation is adopted to relate physical quantities at contact points and at nodes. This work presents the two iterative procedures, that differ in the iteration scheme, performed either on the whole time history (WTH) or in the single time step (STS). The numerical studies concern a 3D finite element model of a RC bridge, 30m long, and a 3D 7-DOFs model of a vehicle. To highlight the significance of the present work, at first previous results are summarized: a direct comparison of the two procedures, where a good agreement is found, has pointed out the validity of the proposed uncoupled approach, allowing the evaluation of the effects of some parameters, such as vehicle damping, bridge static deflection and the choice of the shape functions adopted to impose the constraint equation. Two important effects are investigated in this work. One is the effect of the transverse distribution of the roughness profiles: a non uniform profile under the left and right wheels is adopted, respecting an isotropic PSD function. The other is the effect of the vehicle position over the bridge deck, considered to be eccentric with respect to the longitudinal symmetry axis of the bridge. Both effects reveal to be important and provides better insight into the bridge-vehicle dynamic interaction.
An uncoupled iterative approach for bridge-vehicle coupled systems
MULAS, MARIA GABRIELLA;
2011-01-01
Abstract
Based on the same coupled formulation of the vehicle-bridge dynamic system, written in total displacements and including the effect of the pavement roughness profile, two numerical iterative procedures, named WTH and STS, were previously derived, relying on the same forced uncoupling of the equations of motion. The uncoupled formulation is characterised by time-independent, symmetric matrices. A sufficient generality in the modelling of the two subsystems is retained. A numerical model, not restricted to a particular choice of the adopted elements, describes the bridge; the vehicle is modelled as a multi-body system. Since, in general, the contact points do not coincide with a mesh node, a constraint equation is adopted to relate physical quantities at contact points and at nodes. This work presents the two iterative procedures, that differ in the iteration scheme, performed either on the whole time history (WTH) or in the single time step (STS). The numerical studies concern a 3D finite element model of a RC bridge, 30m long, and a 3D 7-DOFs model of a vehicle. To highlight the significance of the present work, at first previous results are summarized: a direct comparison of the two procedures, where a good agreement is found, has pointed out the validity of the proposed uncoupled approach, allowing the evaluation of the effects of some parameters, such as vehicle damping, bridge static deflection and the choice of the shape functions adopted to impose the constraint equation. Two important effects are investigated in this work. One is the effect of the transverse distribution of the roughness profiles: a non uniform profile under the left and right wheels is adopted, respecting an isotropic PSD function. The other is the effect of the vehicle position over the bridge deck, considered to be eccentric with respect to the longitudinal symmetry axis of the bridge. Both effects reveal to be important and provides better insight into the bridge-vehicle dynamic interaction.| File | Dimensione | Formato | |
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