Nonlinear numerical analysis of prestressed concrete beams and slabs.

Programa de P?s Gradua??o em Engenharia Civil. Departamento de Engenharia Civil, Escola de Minas, Universidade Federal de Ouro Preto.A aplica??o da protens?o em vigas e lajes tem sido difundida cada vez mais, atrav?s do desenvolvimento de novas t?cnicas construtivas e necessidade de solu??es pr?ticas na ?rea da constru??o. Muitos estudos foram e est?o sendo realizados com o intuito de se conhecer bem o comportamento de estruturas protendidas, de forma a tirar o maior proveito, com seguran?a, de suas possibilidades construtivas. O objetivo principal desse trabalho ? implementar um modelo de elementos finitos para an?lise num?rica n?o linear de vigas e lajes de concreto protendido. Dessa forma, foi implementado um elemento finito de interface para an?lise num?rica n?o linear. Este elemento ? capaz de simular tanto o deslizamento que ocorre entre a laje de concreto e a armadura ativa quanto a deforma??o que esta armadura sofre. As perdas de protens?o imediatas e diferidas no tempo foram implementadas. Nas an?lises num?ricas apresentadas no presente trabalho as lajes de concreto s?o modeladas com elementos planos de casca e as vigas modeladas com elementos de barra. O contato entre as cordoalhas e o concreto ? modelado atrav?s de elementos de interface. As n?o linearidades geom?trica e f?sica s?o consideradas na an?lise num?rica. Os exemplos analisados validam o modelo num?rico sugerido neste trabalho mostrando um ?timo resultado quando comparado ao resultado experimental.The application of the prestressed concrete in beams and slabs has been increasingly widespread, through the development of new constructive techniques and need of practical solutions in the area of the construction. Many studies were and they are being accomplished with the intention of knowing well the behavior of prestressed structures, in way to include all the advantages, with safety, of their constructive possibilities. The main objective of this work is to implement a finite element model for nonlinear numerical analysis of prestressed concrete beams and slabs. Thus, a finite interface element was implemented for nonlinear numerical analysis. This element is able to simulate both the slip that occurs between the concrete slab and the tendon as the deformation that this tendon suffers. Immediate and delayed time losses were implemented. In the numerical analyzes presented in the present work, the concrete slabs are modeled with flat plate elements and the beams modeled with bar elements. The contact between the tendons and the concrete is modeled through interface elements. The geometric and material nonlinearities are considered in the numerical analysis. The analyzed examples validate the numerical model suggested in this work showing an excellent result when compared to the experimental result