Fisuración longitudinal de elementos pretensados durante la transferencia de la fuerza de pretensado: II modelización numérica

Splitting artion of the prestressing wire during the transfer of the pretensioning force: II Numerical modelling

The bond between wires and concrete is a fundamental feature to get the transmission of stresses between the two materials in prestressed concrete. The bond is provided by chemical adhesion, friction and ? in case of indented wires- mechanical interlock between the indented wire and the surrounding concrete. The radial component of the bearing force, exerted by the wire indentations, creates a ring tension in the concrete surrounding the wire. The wedging action generated by the indentations is magnified by the Poisson?s egect. This combined effect improves the bond, but it may split the concrete. The splitting of the concrete leads to the loss of confinement of the wire and diminishes the bond between the wire and the concrete. This aspect is very dangerous if splitting exists but they con not be seen by the naked eye. A novel numerical procedure has been developed to model the bond-slip which takes into account the cracking in the concrete surrounding the steel bar. The procedure is based in the elastoplastic formulation and it uses the non associated computational plasticity to modelling the bond behavior. The splitting process is simulated by the cohesive crack model. The numerical procedure accurately reproduces the experimental data of prestressed specimens. The model uses parameters with fully physical meaning, which can be experimentally measured.