Keywords: dynamic analysis, highway bridge decks, statistical analysis, irregular pavement surface, computational modelling, finite element analysis.

Since the late 1980s field reports indicate that highway bridge decks have been submitted to excitation levels, under usual traffic conditions, which have deteriorated their service conditions and structure durability; this can be an indication of under conservative design criteria [1,2,3]. It is therefore desirable to have the problem parameters quantitatively evaluated to better estimate their participation in the structure disruption.

The analysis methodology follows a statistical model running in the time domain. The mathematical model, which includes the interaction between the dynamic properties of the vehicle with those of the bridge, simulates the bridge structure and the vehicle series as a system, the vehicle-bridge system [1,2].

The bridge deck follows a straight beam model made discrete by finite elements and nodal concentrated masses, with vertical translations and in-plane rotations as degrees of freedom. The vehicle simulation uses concentrated parameters of mass, stiffness and damping. Four different types of vehicles are modelled as rigid masses connected by springs and dampers with one, two, four or five degrees of freedom. According to each vehicle model, translational and rotational displacements are considered [3].

One considers a probabilistic definition for the pavement irregular profile. The deck surface roughness is defined by a weakly stationary, second order and ergodic random process based on a well-known power spectrum density of road pavement profiles.

The moving load is formed by an infinite train of similar vehicles regularly spaced and running at constant speed, in such a way as to obtain steady-state mean maximum response quantities of the bridge deck, which are necessary for a fatigue analysis of the deck material; one also considers the generation of a number of pavement surface profiles sufficiently large to sustain a statistical treatment of the results [1,2].

Based on the four vehicle mathematical models developed, a parametric study is undertaken and the conclusions include qualitative and quantitative aspects of the bridge design. The results have indicated in all cases studied, in the present investigation, for usual vehicle velocities, that the dynamical effects on highway bridge decks due exclusively to the interaction of the vehicle suspension flexibility with an irregular pavement surface represent a significant action on the vehicle-bridge system response.

1

Silva J.G.S. da, "Dynamical Performance of Highway Bridge Decks with Irregular Pavement Surface", Computer & Structures, Vol. 82 (11-12), pp. 871-881, 2004. doi:10.1016/j.compstruc.2004.02.016

2

Almeida R.S. de, "Análise de Vibrações de Pontes Rodoviárias Induzidas pelo Tráfego de Veículos sobre o Pavimento Irregular", MSc Dissertation (In Portuguese), Post-graduate Programme in Civil Engineering, PGECIV, State University of Rio de Janeiro, UERJ, Rio de Janeiro, Brazil, 2006.

3

Fryba L. and Pirner M., "Load Tests and Modal Analysis of Bridges", Engineering Structures, Vol. 23, pp. 102-109, 2001. doi:10.1016/S0141-0296(00)00026-2

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