| Popis: |
The paper presents the model for the numerical analysis of prestressed concrete plates and shells. Cases for instantaneous static load and long-term static load are included. The model simulates the influence of material and geometric system nonlinearity. It is possible to include the dominant nonlinear effects of concrete: the creep, shrinkage and aging of concrete, the development of concrete cracks in tension and yielding of the concrete in compression, the changes in the tensile and shear stiffness of cracking concrete. A concise description of assumed non-linear reinforcing steel model is given. Reinforcing steel is modelled as a separate layer with anisotropic material properties i.e. with a possibility to transfer the stresses in the reinforcement bars direction only. Prestressing steel is simulated by 1-D curved elements embedded in the shells finite elements. The numerical procedures, which describe the prestressing contributions and time-dependent analyses, are discussed. The numerical model simulates the prestressing losses that occur during and immediately after the prestressing operation. A distinction has to be made between pre-tensioned and post-tensioned structures in order to take into consideration the immediate losses. The numerical examples are verified by comparison with the results of experimental tests for the analysis of reinforced concrete slabs and prestressed concrete shells. |
