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Numerical iterative analysis for vehicle-bridge dynamic interaction
No full textabstract in: D. Bismor, M.I. Michalczyk, M. Pawelczyk, J. Ciešlik eds., “The Sixteenth International Congress on Sound and Vibration, Krakow, Poland, 5-9 July, 2009, Program and Book of abstracts”, pag. 108, ISBN 978-83-60716-72-
An uncoupled iterative approach for bridge-vehicle coupled systems
No full textBased 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
Effects of the anchoring systems on the dynamic behaviour of the submerged floating systems (SFT)
No full textAn uncoupled approach for vehicle bridge interaction analysis
No full textA formulation of the coupled equations of motion for the bridge-vehicle dynamic interaction problem is proposed. This is derived through the Lagrange’s equation and adopts a compatibility condition at the interface bridge-vehicle, assuming that the two systems are always in contact. The pavement roughness can be considered in a simple way, through a roughness profile either generated from a PSD spectrum or based on experimental data. The coupled equations are forcibly uncoupled, moving the coupling terms to the RHS of the equations as forcing terms. The equilibrium condition at the interface, stated by the action-reaction principle, is then imposed through an iterative solution. Two iteration strategies are developed in the time domain; leaving generality to the iterative approach, separate and uncoupled mechanical models for the vehicle and the bridge are adopted. Both strategies consider: (a) a vehicle moving on the bridge at constant velocity along a straight direction, transmitting vertical contact forces to the bridge; (b) the sum of contributions from the bridge deflection and the pavement roughness as prescribed motion at the wheels of the vehicle.
Procedure WTH iterates over the whole time-history and relies on a general purpose FE code for the structure; an ad hoc code has been developed for the vehicle. Thus, the bridge is subjected to the time history of contact forces, the vehicle is subjected to the time history of prescribed displacements and velocities. Convergence on contact forces involves the rms values during the whole time history. Procedure STS is implemented in an ad hoc developed code that needs the stiffness and mass matrix of the structure as input data. A two-phase iteration strategy within each time step is adopted; in the predicting phase the vehicle is moved to the step final position, in the correcting phase the forces transmitted by the vehicle are updated with the current values of the bridge displacement and velocities. The convergence check involves the variation of contact forces from an iteration to the next one.
The first numerical studies are performed on a simply supported RC bridge, considering a 3D, 7DOFs vehicle model and two simpler 2D, 1 DOF and 4DOFs ones
Iterative Solution Methods for Coupled Vehicle-Structure Systems
No full textSommario su libro p 485-486. Allegata memoria su CD (stessi autori, stesso titolo) di 10 pagin
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