Algebraic Methods for Creep Analysis of Continuous Composite Beams

This paper proposes a simplified time-dependent analysis for continuous steel-concrete composite beams with flexible shear connection, subjected to static actions, settlements of the supports, shrinkage, and prestressing of the concrete slab. By approximating the integral terms with particular quadrature rules (algebraic methods), the integral-differential system, which governs the problem, reduces to a differential system. This provides approximate solutions of the viscoelastic problem directly at the final time, without having to consider the real stress history. Some of the algebraic methods known in the literature (e.g., effective modulus, mean stress, and age adjusted effective modulus methods) are applied to continuous composite beams subjected to the four different actions examined separately. Subsequently, the numerical results obtained are compared with the results of the accurate numerical analysis (general method), and the validity of each simplified method is discussed. Finally, some information on the practical application of the effective modulus and the mean stress methods by means of routine computer programs, are given.