Flexure Mechanics of Partially Polymer Impregnated Concrete Elements.

Flexure and extension analysis of a concrete beam with external layers impregnated with a polymer is presented. Two simplified material models are discussed: 1) brittle-elastic behavior of beam and external layers, and 2) perfectly plastic model. It is shown that besides unstable parts of the moment-curvature curve, the catastrophic failure may also occur for which the bending moment undergoes abrupt drop. Such a behavior is discussed in terms of the catastrophe theory and the topology of equilibrium surface is considered. For perfectly plastic behavior the limiting surfaces are determined in the moment-axial force. A detailed theoretical analysis of beam behavior depending on design parameters such as thickness ratio of reinforced layer and beam or strength ratio of the two materials is given.