Buckling of Reinforced and Prestressed Concrete Members - Simplified Calculation Method

Abstract

S tructural instability considerations provide a special group of design problems for reinforced and prestressed concrete members wherein axial or in-plane forces play an important role in structural performance. The nonlinear behavior of a member due to the actual stressstrain relationship, effects of cracking, creep and current deformations must be duly accounted for in order to carry out realistic strength predictions. On the other hand, simplified methods are needed which are practical to use in actual design situations and which can allow for the nonlinear effects in a sufficiently accurate manner. This paper describes the basic features of structural instability in reinforced and prestressed concrete members such as columns, plates and shells. Simplified methods are discussed, which are based on the tangent modulus theory and ultimate limit state considerations. Several studies have been made by comparing theoretical results with buckling tests on plate and shell specimens. In general, the design methods proposed show good agreement with available experimental results. Emphasis is put on the significance and adequate representation of construction imperfections, specifically geometry and materials. A simplified but powerful design method is given, by which geometric out-of-shape imperfections can