الفهرس 
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Abstract
An Integral Abutment Bridge (IAB) is defined as the bridge whose superstructure, beams and deck, are directly connected to the abutment, without either bearings or expansion joints. The ends of the beams and the bridge deck are integrated rigidly connected with the abutments. The abutments are usually supported on a single row of vertical piles. The research article is devoted to the behavior of straight integral abutment steel-girder bridge with concrete deck supported on bored reinforced concrete piles. The effect of the backfill stiffness, the foundation soil stiffness, the pile diameter, the abutment height and the bridge length on the behavior of the bridge under thermal load variations and the self-weight of the bridge were investigated. Furthermore, two techniques for reducing the concrete pile stiffness and improving the lateral stiffness capacity of the pile and hence, increasing the maximum bridge length limit, are presented in two approaches; predrilled holes for the upper portion of the pile and a noval hybrid foundation system supporting the bridge abutment where the top portion of the pile is H-Pile attached to the concrete pile. Bridges of different lengths were considered. The superstructure and substructure were modeled using 3D finite element through SAP2000 Software. The superstructure was simulated using linear elastic model while the substructure was modeled using nonlinear model to represent the nonlinear behavior of soil-structure interaction. The study revealed that the foundation soil stiffness, the pile diameter, the height of the abutment and the bridge length have significant influence on the substructure demand. Also, the pile predrilled holes and hybrid foundation system significantly decreases the substructure demand and as a result increasing the bridge maximum length limit.