Optimal design of orthotropic highway bridge floors

The rapid development of the numerical methods in StructuralEngineering leads not only to the analysis but also to the optimum design ofthe structures. Therefore, the main objective of the present research work isto develop an optimal design model for the minimum weight of orthotropicHighway deck bridges. The proposed model is developed based onSequential Unconstrained Minimization Technique (SUM.T) in theframework of the Finite Element method.The proposed model has been exploited to study the sensitivity of theoptimal design of orthotropic bridge versus the variations of thicknesses anddepths of cross-sections. Finally, parametric studies for the effects of layoutspacings, depths of cross and main girders and different types of stiffenersfor different orthotropic deck bridges have been carried out. The optimumdesign corresponding to minimum weight is obtained satisfying theconstraints of stresses, deflection and the minimum limits of thicknessesaccording to the codes of practice (AASHTO, BS-5400 and E. CP. , 1989).The live loads are applied according to the modified Egyptian Code ofPractice for loads on structures and bridges (1993).The model is an efficient and globally convergent mathematicalprogramming one for the optimal design of orthotropic deck bridges. Manypractical recommendations have been concluded and submitted to thepractitioners for optimal design of minimum weight of orthotropic deckbridges./