Moving Force Identification—A Frequency and Time Domains Analysis

Abstract

This paper addresses the problem of identifying a system of forces from vehicle crossing a guideway using only the vibration responses caused by the forces as the input without knowledge of the vehicle characteristics. The vehicle is modeled as a single axle and two-axle loads with fixed axle spacing moving on a simply supported beam with viscous damping. The equations of motion of the beam are obtained through modal coordinate transformation, and the resulting set of equations relating the Fourier transforms of the responses and the moving forces are converted into time domain by a new method proposed by the authors. Correctness of the identified forces are checked by the correlation between the measured responses and the responses reconstructed with the identified forces moving on the beam. Experimental result shows that the method is effective to give good correlation when both measured bending moment and acceleration are used, and it is faster and it gives more accurate estimate of the total mass of the vehicle than an existing method.

A general solution to the identification of moving vehicle forces on a bridge

“…Many of the current methods of MFI can be loosely divided into two categories, those that use the finite element method [5][6][7][8] and those that employ an exact solution method coupled with some form of system identification technique [9][10][11][12][13]. The solutions to the MFI problem using an exact solution method are generally subject to large fluctuations in the predicted force at the start and end of the time history due to the ill-conditioning of the least squares formulation of the problem.…”

On the basic phenomenon of soil-structure interaction on the free vibration response of beams: Application to railway bridges

“…This model is appropriate when the deck vertical response is mainly governed by its longitudinal bending modes and when the interest focuses on the structure behaviour, and not the vehicle's, as vehicle-structure interaction is disregarded. Numerous works are reported in the literature in this regard [5][6][7][8][9][10].…”

On the use of bridge weigh-in-motion for overweight truck enforcement

“…In the late 1990s and early 2000s, several researchers, investigated the differences between theoretical B-WIM algorithms and bridge measurements, both theoretically using complex vehicle-bridge dynamic interaction models and experimentally using data from four bridge sites (González 2010;González and OBrien 1998;Law et al 1997;Law et al 1999;Yu and Chan 2003;Zhu and Law 2001;Law et al 2004;Law and Fang 2001). The influence of dynamics and multiple sensors on the accuracy of B-WIM systems is addressed.…”