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Dynamic response of a multi-span, orthotropic bridge deck under moving truck loading with tandem axles

Fisli Youcef, Rezaiguia Abdelouahab, Guenfoud Salah, Laefer Debra F.

Diagnostyka

2019

Vol. 20, No. 4

37--48

In this paper, a new three-dimensional vehicle with tandem axels at the rear is developed to determine dynamic response of bridge deck under load applying truck. The vehicle is modeled by a three-axle dynamic system with 9 degrees of freedom to accurately simulate the disposition and the intensity of loads on the bridge deck. The bridge deck is modeled by a thin, orthotropic, multi-span plate. The road surface irregularities are modeled by a random function characterized by a spectral roughness coefficient and power spectral density. The modal method is used to solve the equation of motion of the bridge deck. Equations of motion of the vehicle are obtained using the virtual work principle. The coupled equations of motion vehicle/bridge deck are integrated numerically by Newmark’s method. A computational algorithm in FORTRAN is then elaborated to solve the integrated equations of motion in a decoupled, iterative process. A numerical example of an orthotropic, three-span bridge deck, excited by a 9 degree of freedom truck is presented. The resulting distribution of the Dynamic Amplification Factor (DAF) on the bridge deck does not reflect any particular trend, because high values can be obtained at points where the vertical displacement is small. The DAF is significant only under the interaction force. Thus, the road surface roughness was shown to have a significant influence on the dynamic vehicle/bridge deck interaction forces.

Alternatives for bridge surfacings with orthotropic plated deck: a fatigue point of view

De Backer H., Outtier A., Van Bogaert P.

Foundations of Civil and Environmental Engineering

2008

No. 11

5-16

Steel orthotropic decks are sensitive to stiffener-to-deckplate fatigue. Larger traffic volumes and concentrated wheel loads contribute to this phenomenon. Traditionally, the effect of the wearing courses is taken into account through load dispersal under 45° reducing the stress at the deck plate surface. However for asphalt surfacings this effect is small. A more reliable solution could be present if a structural cooperation were present between the deck and the surfacing. In this paper, the results are presented from a study of various alternatives for a lightweight bridge surfacing contributing to fatigue reduction at the stiffener-to-deckplate intersection. Asphalt, neoprene and composite layers are considered as well as honeycomb sandwich panels. The effect of the solutions is measured by strain gauges on an orthotropic bridge prior to the final surfacing installation. The results are compared with conclusions derived from a finite element model and indicate that depending on the type of layer, a 20 to 30 % reduction of stresses is possible, resulting in a 3 to 5 times longer fatigue life, without increasing the deck weight.