Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

Step-by-step solution strategy for segmental prestressed concrete bridge calls for: (i) time dependent effects of creep and shrinkage of concrete, and relaxation of prestressed steel; (ii) losses due to friction and anchor setting of prestressing tendons; (iii) sequence of construction, and change of geometry and support conditions; (iv) effects of nonprestressed steel on the redistribution of stresses. These significant parameters have been accounted for to obtain the time dependent serviceability analysis of two segmental prestressed concrete bridges over the Nile River, i.e., El-Warrak Bridge and Talkha Bridge, utilizing Eurocode specifications. Redistribution of stresses in concretedue to time-dependent effects during construction and after a long time of operation is one of our objectives. The final results lie between two limiting time independent solutions: (a) superposition all partial stresses for each construction step using corresponding statical system; (b) assuming all loads and prestress forces to be applied on the final statical system. This thesis is to report on estimated contributions of each of the two time-independent cases in order to minimize the difference with results obtained from the time-dependent analysis.To this end, a number of robust, and computationally efficient, algorithms are presented and integrated through software ESTMATOR, which casts the optimum parameters as a minimum-error nonlinear optimization problem with constraints and solves it with the sequential quadratic nonlinear programming technique

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