Abstract

This work focuses on evaluating the vertical movements that appear when a pedestrian is walking on a slender beam-like structure. For that, the pedestrian is modelled by a dynamic system consisting on a concentrated mass, located in its center of masses, supported by two springs which simulate the stiffness of the legs. The success of this simple mechanical model is that the resulting contact forces are well adjusted to those observed experimentally for human gait. In this way, the structure is undergoing the moving mass and is loaded with realistic forces, resulting in a proper assembly to study interaction effects. The dynamic response of the beam is obtained at any coordinate by the modal superposition method, considering a finite number of modes. Differential equations of the resulting coupled problem are solved using proper numerical techniques. Solutions obtained for different scenarios (depending on the mass of the pedestrian with respect to the mass of the beam and on the pace) are presented.

Abstract

In this contribution, a new form of semianalytical results related to inertial objects that are traversing homogeneous infinite structures, introduced in previous author's work, is used to analyze one-, twoand three-layer models of the railway track. The aim of these analyses is determination of the critical velocity of a moving force and of the onset of instability of moving masses or oscillators. As one of the most important conclusions, it will be shown that in the case of two moving proximate masses, damping can act in the opposite direction than expected and owing to the dynamic interaction, the onset of instability can be shifted deeply into the subcritical velocity range.