Finite Element Analysis of Permanent Deformation and Responses under Different Vehicular Load Speeds
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Date
2020-01
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Addis Ababa University
Abstract
The increase of dynamic loads exerted on the pavement is one of the major causes that
shorten the pavement service life. The current pavement design procedure which
incorporates static loads in the structural design of pavement makes the situation critical.
Hence, decreased riding quality, discomfort and increased vehicle operating cost that
influences overall transportation costs are seen. Thus, a vehicle loading speed must be
given attention in dynamic analysis due to its effect on tire-pavement interaction and
pavement response values.
In the study, three-dimensional finite element analysis used to simulate the deformation
of the pavement surface and sub-grade by different vehicular speeds. ABAQUS software
is employed to develop total of five three-dimensional finite element models. Each
pavement models represent selected vehicular speeds by considering similar material
characterization, single axle single tire load configuration and necessary boundary
conditions. The vehicle speed along the wheel path is simulated by progressive shift of
the tires over the pavement loading area.
From the analysis of the pavement models, it was found that lower speeds have longer
contact time with flexible pavement than higher speeds. This is due to time of loading is
the function of tire imprint length and speed. Also, asphalt concrete behavior as
viscoelastic material plays an important role. Moreover, the greater static effect of
loading makes the reduction in lower speeds is more than higher speeds. Though
increasing velocities make the dynamic's effects of loading more than static's effect of
that, it cannot higher than load's static's effect at low speeds. Hence, accumulated strain
increases with an increase in loading time.
In addition, vertical strain and stress distribution increase and decrease linearly along the
wheel path as loading amplitude varies in each step time. As a result, maximum stress
magnitude under load center for single axle configuration is higher in 20Km/hr than
100Km/hr speed. It is also worthy to mention, load's dynamic effect is less considerable
at the top of subgrade. This is due to deeper position of extracted data and the effect of
layers' weight. Hence when speed increases higher than 60Km/hr, a low decrease in
strain magnitude is observed.
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Keywords
Dynamic analysis, ABAQUS, Finite Element Analysis, HMA, Vertical Strain