Numerical Model for Prestressed Composite Concrete Flexural Members

A finite element numerical model for the analysis of composite construction structures has been implemented using the hybrid type formulation for planar frames structures. The hybrid type finite element is regarded as a theoretically exact approach for force and curvature distributions. This approach allows the use of long elements, consequently improving computational efficiency and enhancing the unbonded tendon strain calculation. The computer programme considers bonded and unbonded prestressing, cyclic loading, time-effects and geometrical non-linearity. For composite construction analysis, new layers may be added to the cross-sections at any time, elements may be added to the structure during analysis, reinforcing bars may be included in the elements and bonded or unbonded tendons may be stressed during analysis. Time is a parameter used for the description of loading and construction histories, even in time-independent materials problems. Such approach for composite construction allows the modeling of complex histories in a simple manner. Results are presented comparing numerical and experimental behaviours, including unbonded simply supported prestressed beams, cast-in-place continuity of hollow-core slabs and prestressed cast-in-place continuity of pre-cast beams. Numerical and experimental curves show a good agreement in all examples, demonstrating an adequate performance of the model.