Multiscale techniques allow for the efficient numerical investigation of the structural behavior considering a complex reinforcement distribution. The present contribution compares two multiscale methods in terms of their applicability for thin-walled, carbon-reinforced concrete structures. The first is a coupled multiscale method that simultaneously solves multiple finite element problems (FE2) and provides a smeared material model. The second is the multiscale projection method (MPM) which is capable of reproducing localization effects within a certain domain and their effect on the overall failure of the structure.

For both methods, the problem is divided into a macroscopic and a mesoscopic scale. The former describes the statical system of the shell. The latter considers the distribution and geometry of the reinforcement. Micro-CT data acquired and processed in the scope of CRC/TRR 280 give detailed insight into the mesoscopic scale.

The coupled multiscale model aims to define a representative volume element (RVE) that captures the mesoscopic behavior at each macroscopic point. Shell elements cover the macroscopic behavior of the statical system, while scaled boundary elements represent the mesoscopic model.

The MPM magnifies certain, spatially limited areas where localization phenomena might occur. The overall mesoscopic effects are incorporated by the projection of the mesoscopic stresses onto the macroscale. Here, both scales are modelled using three-dimensional finite elements. On the mesoscale, the extended finite element method (XFEM) is used to reproduce the reinforcement heterogeneities.

In future work, both methods will be used for the analysis of shell-like dissolved concrete structures.