Nonlinear geometric, material and time dependent analysis of segmentally erected, three dimensional cable stayed bridges

A numerical method of analysis has been developed to trace the response of segmentally erected, three dimensional, reinforced and prestressed concrete cable stayed bridges due to either immediate or sustained loads. The analysis incorporates the effects of both material and geometric nonlinearity. Time dependent effects due to load history, creep, shrinkage and aging of concrete and relaxation of stress in the prestressing steel are included in the analysis. The response of concrete structures can be tracked both before and after cracking, through the inelastic range and past the peak resistance through strain softening behavior.; This numerical procedure can predict the response of the changing structural configuration as it evolves progressively through different phases of cantilever construction of cable-stayed bridges. Any statically feasible construction sequence may be considered, including the installation or removal of deck or tower elements, placement and stressing of prestressing tendons, installation, stressing, restressing or removal of permanent and auxiliary cable stays. In addition boundary restraints may be added or released at any point in time.; Tower and deck segments are modeled with multi-slice fiber beam-column elements with variable shape functions that are updated as the state of the element changes. Two different types of cable elements have been developed, a shallow cable element appropriate for modeling cable-stays and a general cable element which may be used for modeling large sag cables such as those used in suspension bridges. Nonlinear material constitutive models are used for concrete, reinforcing steel, prestressing steel and cable-stay steel. Refined creep models are used for concrete. Nonlinear geometric effects can be included in all structural elements.; This analytical method is incorporated into a computer program CALBRG. Results from a numerical example of a segmentally erected, cable stayed bridge, which is constructed sequentially using a cantilever erection scheme and then loaded to failure, are presented to demonstrate the application of the numerical procedure to an actual design.