Non-linear analysis and moment redistribution of prestressed concrete members

Abstract

Most of the existing codes of practice allow moment redistribution to be applied to reinforced concrete design with upper limits of 20–30%. It is, however, questionable whether the same limits are valid for the design of prestressed concrete members. Research in this area dates back to the 1950s, but investigations have mainly focused on the behaviour at different servicing limits and the effects of various parameters. Work has seldom been done on the effects of moment redistribution on structural safety, as the load-carrying capacity can be compromised with increase in moment redistribution owing to the limited ductility of concrete sections. In the present study, a method for non-linear finite-element analysis is developed to examine the relationship between the reduction in load-carrying capacity and the moment redistribution applied to the design of prestressed concrete members, and how such a relationship is affected by section deformability and plastic hinge lengths. Results suggest that due care must be exercised when codified moment redistribution for prestressed concrete members is applied.