الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
In Egypt, where highway bridges are to be constructed on soft cohesive soils, the bridge abutments are usually founded on rigid piles, whereas the earth embankments for the bridge approaches are directly founded on the natural soft ground. Consequently, excessive differential settlement frequently occurs between the bridge deck and the bridge approaches resulting in a “bump” at both ends of the bridge deck. Such a bump not only creates a rough and uncomfortable ride but also represents a hazardous condition to traffic. One effective technique to cope with the bump problem is to use a reinforced concrete approach slab to provide a smooth grade transition between the bridge deck and the approach pavement. Investigating the performance of geotechnical and structural of approach slabs and revealing the fundamental affecting factors have become mandatory. In this paper, a 2-D finite element model is employed to investigate the performance of approach slabs. Moreover, an extensive parametric study is carried out to appraise the relatively optimum geometries of approach slab, i.e. slab length, thickness, embedded depth and slope, that can yield permissible bumps. Different geo-mechanical conditions of the cohesive foundation soil and the fill material of the bridge embankment are examined.Using the finite element model, the present study paper simulated several cases. The length, the thickness, the embedded depth, varying thickness of the approach slab and sleeper slab at the free end of the approach slab were changed to study their influence on the bump at the free end of the approach slab.
The present study investigated the effect of different factors on the behavior of approach slab that represent different types of compressible soil, soft, medium or stiff and different types of fill embankment, well or poorly compacted. Total settlement at the free end of the approach slab (Δ0), Total bump value at the free end of the approach slab (Δ1), the relative bump value within a 3m width at the free end of the approach slab (Δb), the normal stresses at the free end of the approach slab (σN), the maximum bending moment on approach slab (Mmax) and the ratio of Xσ to approach slab length (Xσ/L) were predicted with finite element modeling.