Within this paper, a 3D numerical model for the fluid structure interaction under dynamic load, has been developed. Partitioned approach has been used, where the construction and fluid are solved separately and by different methods. For the analysis of construction, a previously developed model based on the finite element method (FEM) has been used, which was improved by introducing the drilling stiffness of the degenerated isoparametric final element of the shell. For the analysis of fluid, a previously developed model based on the method of smoothed particle hydrodynamics (SPH) has been used, which was improved by introducing additional correction of fluid pressures values along the boundaries of the computer domain. The model is primarily developed for simulation of steel structures that can be described by shell elements (water tanks, reservoirs, etc.). The model can be used to describe the main nonlinear characteristics of the construction steel: flow (yield) under compression and tension and evolvent of plasticity. It is also possible to simulate the basic nonlinear characteristics of the fluid (compressibility, viscous flow and turbulence). Experimental investigations of the interaction of open rectangular reservoirs and water on the shake table were performed within this paper. Experimental investigations have contributed to additional knowledge of the real behaviour of shell structures that are in contact with the fluid and exposed to different dynamic loads. In addition, an experimental database for verification of the developed numeric model was created. Numerical tests performed by using a developed numerical model show its reliability and application. Model verification was performed on the example of the results of the experimental investigations performed within the paper but also from the numerical and experimental results from available literature. Finally, the most important conclusions of the conducted investigations are listed.