The design, analysis and construction of offshore structures as well as their modeling are one of the most demanding sets of tasks faced by engineering profession due to the complexity of structural designs and the large volume of elements used in the model. Finite element analysis (FEA) technology has become a very important tool for evaluating the structural integrity of massive and gigantic structures of which offshore platforms is an example. Offshore structures when installed are constantly faced with different forces/loads ranging from environmental to accidental loads and the later was the impacting load under consideration. This paper carefully illustrates the design and analysis approaches and requirements for a reinforced concrete based gravity platform, a fixed type of offshore structure which was subjected to a crash load and simulated with a computer based finite element analysis tool-ANSYS EXPLICIT DYNAMICS. The scenario was a collision between an offshore transporting vessel and the said fixed platform. Impacting velocities of 5m/s,10m/s, 16m/s, 50m/s and 100m/s were used and results obtained for deformations and stress induced. The study was done to see at what velocity the structure compromise its load bearing capacity and it was observed that the deformation was proportional to velocities increase.