VOL. 15, NO. 2, JANUARY 2020 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences ©2006-2020 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 186 HORIZONTAL LAYOUT BEND OF BRIDGES STRUCTURE EFFECTS ON THE STATIC DESIGN INTERNAL FORCES: EVALUATION AND OPTIMIZATION STUDY Ali Fadhil Naser and Hussam Ali Mohammed Department of Building and Construction Engineering Techniques, Al-Mussaib Technical College, Al-Furat Al-Awsat Technical University, Iraq E-Mail: ali_hu73@yahoo.com ABSTRACT Horizontal layout bend was an important factor in the design of bridges structure depending on nature of bridge location within construction area. The aim of this study was to evaluate and optimize the different designs of bridge horizontal layout bends and compare the results with horizontal layout straight of bridge by depending on the application of static analysis according to finite element analysis method. Static analysis results showed that the straight model had the minimum values of static internal forces. Therefore, this model gave higher resistance to effects of applied loads and the horizontal layout straight of this type of bridges was suitable for design. Keywords: horizontal layout, box girder, bridge, finite element, static, dynamic. 1. INTRODUCTION Bridges constitute a critical link in the highway network and require a large capital investment for construction and maintenance. The bridge is a civil structure which is constructed to cross a dell, highways, rails of trains, waterway, and others barriers [1], [2] [3]. Bridges can be designed to carry and allow the loads to cross the obstacles. These loads include vehicles loads, trains, peoples, and animals. There are four types of bridges can be used. These types include beam bridges, arch bridges, cantilever bridges and suspension bridges. Bridges can deflect when subjected to different types of loads. Bridges must have enough stiffness to resist the effects of loads. Each member of bridge must be strong enough [4]. The layout and position of the bridge structure depends on the traffic volumes and conditions, therefore, the bridge must be located to serve the traffic movement between two sides of bridge structure. Generally, different traffic situations and site state will influence the selection of bridge position and layout. The most important factor is layout of bridge with respect to topographic crossing when the position of bridge is decided to select [5]. The pre-stress scheme of concrete is known as the application of pre-tension loads of concrete structure before subjected to service loads. It is a type of concrete that internal stresses are introduced by means of high strength pre-strained steel tendons. The purpose of this scheme is to develop the structural performance in particular ways. The pre-stressing concrete consist of two categories of pre-stressing, pre-tensioned pre-stressed and post-tensioned pre-stressed [6], [7], [8], [9], [10]. Box girders is widely used in the construction of the highway and city pre-stressing concrete bridges and it has a good structural performance, stiffness, bending resistance, high employment of section, and good economic income [11]. The most important points of structural analysis is to review the static responses of a structure and to get the distribution of internal forces system by determining vertical displacement (vertical deflection), tension stress, axial force, bending moment, torsion moment, and compressive stresses. According to different types of applied loads, a linear elastic model is assumed in the structural analysis. The finite element method (FEM) is a appropriate employment to find solution of differential equations for the structural engineering functions [12], [13], [14] Analysis of bridge includes engineering software models, which are using suitable material properties, boundary situations, and different types of loads. Parts and bonds joints of bridges are designed to carry all possible loads such as structure dead load, prestressed load, vehicles load, wind load, and temperature load [15], [16]. There are two methods of bridge analysis. These methods are static method and dynamic method. The selection of suitable analysis method depends on a number of factors. These factors include the objective of analysis, significance of bridge structure, methods obtainable for analysis, type of bridge, and soil conditions. Most engineering software are using finite element in the analysis. The finite element method is known instrument for the answer of complex structural engineering problems. In this method, the real range is replaced by an equivalent idealized structure composed of separate elements, referred to as finite elements, connected together at a number of nodes [17], [18]. The aim of this study is to evaluate and optimize the different designs of bridge horizontal layout bends and compare the results with horizontal layout straight of bridge by depending on the application of static analysis according to finite element analysis method. 2. DESCRIPTION OF BRIDGES MODELS In this study, continuous box girder with two cells bridge is used. Nine models of bridges are selected according to horizontal layout bend type. All models have same span length, width, and depth which is equivalent to