D. Le Houédec

Surface vibration due to a sequence of high speed moving harmonic rectangular loads

The transmission of vibrations over the surface of the ground, due to high-speed moving, vertical harmonic rectangular loads, is investigated theoretically. The problem is three-dimensional and the interior of the ground is modelled as an elastic half-space or a multilayered ground. The transformed solutions are obtained using the Fourier transform on the space variable. A new damping model in the spatial wavenumber domain, presented in Lefeuve-Mesgouez et al. [J. Sound. Vibr. 231 (2000) 1289] is used. Numerical results for the displacements on the surface are presented for loads moving with speeds up to and beyond the Rayleigh wave speed of the half-space.

Ground vibration in the vicinity of a moving harmonic rectangular load on a half-space

The transmission of vibrations over the surface of the ground, due to a moving, vertical harmonic rectangular load, is investigated theoretically. The interior of the ground is modelled as an elastic half-space. The transformed solutions are obtained using the double Fourier transform. Numerical results for the displacements on the surface are presented for loads moving with speeds up to the Rayleigh wavespeed of the ground.

A dynamic stiffness analysis of damped tubes filled with granular materials

Abstract A non-conservative dynamic stiffness method is applied to damped flexural vibrations of a uniform rectangular tube filled with granular material. An hypothesis of internal resonance in the granular material is taken into account by means of a frequency-dependent apparent mass which materializes as the granular material damping effect. This apparent mass is injected into the equations of motion of the tube assimilated to a Timoshenko beam. Equations are then solved and the frequency-dependent dynamic stiffness matrix is established. A Newtonian procedure allied with a counting algorithm is used to obtain eigensolutions of the undamped empty tube. These solutions are then taken as initial approximations of a Rayleigh quotient iteration algorithm which provides damped eigensolutions. A general program has been developed under MATLAB environment. Despite the apparent simplicity of the granular material behaviour model, results are encouraging.

Numerical modelling of the cyclic behaviour of the basic components of steel end plate connections

Abstract This paper aims at developing a new methodology based on finite element (FE) techniques with a combination of several other methods to extend the component-based design philosophy of EC3 to the cyclic behaviour of end plate connection. In the first part, the experimental procedure for studying the behaviour of an isolated T-stub as the main component of an end plate connection under monotonic and cyclic loading is presented. The second part comprises the four steps necessary to build the analytical model. Firstly the monotonic and secondly the cyclic FE models of these specimens are discussed and validated. Then, a mathematical energy balance model is developed to reproduce the cyclic response. This model is the basis of a mechanical model which predicts the behaviour of a T-stub which constitutes the main component of connections. With these data, a spring model is used to predict the moment rotation curve for an isolated end plate connection.