Casings of machinery and support structures have an influence on the rotordynamic behavior, which is commonly considered by simplified models (e.g., one degree-of-freedom models). These are in many cases insufficient. Hence, more accurate modeling approaches are required, which can be used in the design process or the rotordynamic calculation to achieve a better representation of the overall vibrational behavior. To study the effects of casing and supporting structures on rotordynamics, the casing modal parameters of an axial compressor are determined by an experimental modal analysis. In parallel, a numerical model is established. As experimental data are rarely found in the literature, this work focuses on the parameter identification of the casing structure. The results are subsequently incorporated into a model updating strategy, in order to tune and improve the numerical model. Experimental and numerical data are compared to assess the quality of the data and the results gained. The ultimate objective is a reduced order model, which can be integrated in existing rotordynamic tools via an interface while keeping the calculation time low.