Comparative Study of Fluid-Structure Interaction Modeling Techniques Using Solid Elements, Joint-Based Method, and Additional Dead Load in SAP2000

Fluid-Structure Interaction (FSI) can cause sloshing effects that affect a building’s structural response, either positively or negatively. Accurate FSI modeling is essential, especially for structures with swimming pools or water tanks. This study used SAP2000, a Finite Element Method (FEM)-based software, to model FSI through three approaches: Solid Elements, Joint-Based Method, and Additional Dead Load Method. Laboratory tests on a three-story building prototype with a rooftop water tank were used to validate the analysis. Three tank sizes and seven water height variations were evaluated under sinusoidal sweep dynamic loading. Results showed that damping values significantly influenced FSI modeling, with optimal values ranging from 1.4% to 3.9%, matching experimental shaking table data. The Solid Elements method yielded structural displacement results closest to the experimental data, with average differences of 13.62% and 13.81% lower than the Joint-Based and Additional Dead Load methods, respectively. The latter two methods tended to overestimate the structural response. Additionally, sloshing effects were effectively captured only by the Solid Elements approach. These findings highlight the importance of selecting appropriate modeling techniques to ensure accurate simulation of FSI in building structures.