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Abstract he aim of the current research is to consider the effects of continuity, skew and diaphragm on the live load distribution characteristics of skew steel bridges. Current specifications including the AASHTO Standard Specifications 1996 and AASHTO LRFD 1998 Specifications do not account for reduction in moments due to the effects of transverse cross bracing and continuity resulting in conservative bridge design. The objective is fulfilled by conducting an extensive parametric study on several bridge models to evaluate the effect of the parameters. A theoretical two - equal span bridge model was constructed using the finite element method. The deck slab was modeled as isotropic fournodded shell elements with six degrees of freedom at each node. The steel girders were modeled as three dimensional beam elements with six degrees of freedom per node and were connected to the shell elements through rigid links. The analysis was performed using the finite element commercial program SAP2000. An AASHTO Standard truck was selected and positioned in such locations to maximize both positive and negative moments. These positions were determined by developing influence area diagrams .ased on the results of the parametric study, the live load distribution factors were computed and compared to those of AASHTO 1996 Standard Specifications and LRFD Specifications. Additionally, an innovative technique based on correlating the deflected shape of cross bridge sections with intermediate diaphragms equivalent deck slab thickness was used to find the effect of cross diaphragms. Further, the stiffness of typical bridge was estimated using a twodimensional analysis. Allowing determining live load distribution factors using two - dimensional bridge models. |