Journal of University of Duhok, Vol. 32, No.2 (Pure and Eng. Sciences), Pp 40-51, 3232 (Special Issue) 3 rd international conference on recent innovations in engineering (ICRIE) Duhok, September 9-10-2020 bassam.qasim@spu.edu.iq 1 Corresponding author: Darbandikhan Technical Institute, Al-Sulaymania 04 PROPOSED EFFECTIVE WIDTH CRITERIA FOR SLAB DECK BRIDGES UNDER MILITARY TRACKED LOAD BASSAM QASIM ABDULRAHMAN * Dept. of Surveying, Darbandikhan Technical Institute, Sulaimani Polytechnic University, Al-Sulaymania, Kurdistan Region-Iraq (Accepted for Publication: December 8, 2020) ABSTRACT For any slab deck bridge, the ultimate loading strength is obtained based on the distribution of that loading to a slab effective width that recommended in the adopted specifications. In this study, a simplified procedure with a design equation is presented. This procedure depends on the determination of the moments developed in a slab deck bridge and thus the slab effective width that loading is distributed to. The study employs the Iraqi military tracked load. The procedure applies to right, simply supported slab deck bridges with and without edge stiffening beams based on the aspect ratio that represents the ratio of the slab width to length. A 3D finite element analysis by a well-known programme ABAQUS was conducted to analyse the whole bridges and to give the values of moments that will be used in the derivation of an equation to calculating the slab effective width. Furthermore, a comparison between the effective width of this study and the AASHTO and LRFD specifications was conducted. It is found that this method gives some conservative results in comparison with AASHTO and LRFD standards because other standards have some limitations, besides not to take in consideration all the parameters required. KEY WORDS: Slab bridges, Military load, Tracked load, Effective width INTRODUCTION nalysis of bridges is complicated because of the variety in the bridge geometry, type of supports and the applied loading (Deng et al 2018). Experimental, analytical and more recently numerical studies have been proceeded to improve the techniques used in the analysis and design. Furthermore, they are also used to give more understanding to the structural behaviour of the bridges and to demonstrate the load-carrying capacity of the bridges under more loading. Unfortunately, these studies have not resulted in a realistic and simple procedure. Theoretical studies vary based on their assumptions. Analytical studies are not possible unless simplifications to the assumptions and reduction of the problem to a one that can be solved. Loading distribution is the key element to the bridge engineers in the design and analysis of bridges because the slab in every bridge is designed for their loading (Drar et al 2016)]. Furthermore, it is also important to know the width of the slab which is effective in carrying the bridge loading. So, many studies were conducted to know this width as follows: The basic concept of the effective width was first developed by Goldbeck and Smith (1916) and Goldbeck, A. T. (1917). They obtained the effective width from the stress distribution over the slab width. This width was attributed to the effective slab width as the effective action from the maximum stress distributed over the slab effective width equals the action resulting from the variable stresses over the slab entire width as explained in Figure 1. Generally, they considered the effective width as eighty per cent of the span length. A