engleski

Numerical Analysis of Prestressed Concrete Composite Shells under Various Loading Conditions

The prestressed concrete shells are complex composite structures made of concrete, reinforcing steel and prestressing steel. Thereby, the geometry and material properties of the shell are usually variable across its surface and thickness, as well as the quantity and arrangement of rebars and tendons. The tendons can be bonded (also called grouted) or unbonded (not grouted) to the concrete. The problematic of adequate numerical modelling of prestressed concrete composite shell complicates additionally due to the rheological effects of concrete (creep, shrinkage and aging), the slippage between steel and the surrounding concrete, and the prestressing force losses due to several time effects (short term and long term). In this study a model for numerical analysis of prestressed composite shells under various loading conditions is presented. The short and long term static loading, cyclic and dynamic loading as well as unloading can be simulated. The model is based on the finite element method and can simulate the most important nonlinear effects of concrete, reinforcing steel and prestressing steel, as well as its interaction effects. The developed model can simulate different nonlinear effects of concrete such as: the creep, shrinkage and aging, the propagation of cracks in tension and yielding in compression, the cracks opening and closing, and the changes in the tensile and shear stiffness in cracking zones. The reinforcing steel is modelled as a separate layer with anisotropic material properties while the prestressing steel is simulated by 1-D curved element embedded in the shell finite element. The accuracy as well as the efficiency of the developed numerical model has been verified by comparing the numerical results with experimental data obtained by several tests. It is believed that the developed model can be useful in engineering practice.

prestressed concrete ; composite shells ; experiment ; numerical model

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