Many problems in structural engineering require considering interactions between solids and fluids and/or between different physical phenomena, like thermal, hygral or chemical processes, for an appropriate description of the material behavior and of the structural response. This particularly holds for materials like concrete and soils. They are characterized by a certain degree of permeability allowing liquid or gaseous phases to enter the pore space and to interact with the surrounding solid phase. Since the resulting interactions between the different phases may have a strong impact on the structural behavior, they have to be accounted for appropriately in numerical models. Hence, this mini-symposium is devoted to the presentation and discussion of current developments of multi-phase models and related applications in structural engineering.