Offshore steel structures are widely used around the world, e.g., in Gulf of Mexico, the Middle East, and the North Sea. These structures are costly to build, and any damage to them could be catastrophic financially and environmentally. There are many factors that could possibly affect the health of these steel structures, particularly hydrodynamic forces. These forces cause the structure to vibrate and in the long run could lead to fatigue failure. Therefore, measures have to be taken in order to prevent these structures from failing. Magneto-rheological (MR) dampers are proven as a feasible alternative to reducing structural vibrations. An experimental setup is built in our laboratory to improve the dynamic modeling of steel jacketlike structures and study the effectiveness of MR dampers in decreasing the hydrodynamically induced vibrations. The structure is analyzed theoretically and experimentally, and the results are presented here.