Efficient nonlinear analysis of elasto-plastic 3D R/C frames using adaptive techniques

This paper presents a new nonlinear analysis method for three-dimensional reinforced concrete (R/C) frames employing adaptive analysis concepts. The first two components of the proposed adaptive method, namely the elastic and elasto-plastic beam–column formulations, are described. The details of automatic mesh refinement, which is the third component of the adaptive method, are then presented. These include the construction of an effective interaction surface representing generalised stress states at the elastic limit, the determination and checking of generalised stresses for exceeding the elastic limit along an elastic element, and the refinement of an elastic element into an appropriate number of elastic and elasto-plastic elements. Examples are finally presented to illustrate the accuracy and efficiency of the proposed analysis method.