Inflatable Offshore Fender Barrier Structures (IOFBS) are anti-terrorist security structures that function primarily to either stop terror bound vessels from reaching valuable offshore structures, incapacitate its crew or delay the vessel's progress until secondary security measures can be put in place. In this study, an advanced and efficient modelling technique for impact simulation of the structure and similar multi-physics systems is presented. Numerical implementation of this modelling technique, using Abaqus finite element code was described and used in the impact simulation of the inflatable structure based on its current design as well as an alternative design of the structure following impact of a typical vessel hull were carried out and results from the two designs provisions were compared. From the results, recommendations for improvement of the current design are also reported. This is desirable in ensuring high reliability of the structure in meeting its design objectives.