Análisis no lineal y comportamiento hasta rotura de estructuras de hormigón pretensado con tendones no adherentes

Nolinear anlysis and behaviour until rupture of prestressed unbonded concrete structures

A methodology for the nonlinear structural analysis ohf unbonded prestressed concrete technique is here presented, for structures composed by linear members, being suitable to consider phases beyond cracking of concrete; for so doing, concrete-tendon interaction is assumed to be governed by simple friction. Fulfiling nonlinear range, some comments on the influence of prestressing, bonded or unbonded, on second order analysis of compressed slender elements are also included. As a continuous reference, the better known technique of bonded tendons is used along the work, and so a copmparison of the respective behaviour in these ohases is made, concerning specially ultimate resistance. in order to develop such an analysis, and for better permiting the proposal of practical conclusions, a simple example is also studied; in particular the increasing Delta P of tendon force, used in practical calculation for obtaining the joint concrete-steel cross-sectional responese, is examined. Finally, some general conclusions linked to this technique are pointed out, in view to its application for these linear structures, nowadays related mainly to civil engineering works; but, depending on their possible extrapolation, also for others, such as two-dimensional ones (slabs) being used from many years in building construction.