NONLINEAR ANALYSIS OF PRESTRESSED CONCRETE FRAMES

A numerical procedure based on the finite element method for the material and geometric nonlinear analysis of plane prestressed concrete frames including the time dependent effects due to load history, temperature history, creep, shrinkage and aging of concrete and relaxation of prestress is developed. The procedure is capable of predicting the response of these structures throughout their service load history as well as throughout elastic, inelastic and ultimate load ranges in one complete analysis. Time dependent variation of concrete properties is recognized. Concrete creep is evaluated by an efficient numerical procedure based on the age and temperature dependent integral formulation. Varied material properties within a frame element is accounted for by a composite concrete and reinforcing steel layer system. The contribution of prestressing steel is incorporated directly. A series of numerical examples is presented.