The design strength of a ship against the extreme loads is to be checked using Global and Local Strength Analysis (GLSA). GLSA process is performed based on the first principle calculation methods. It requires a 3D diffraction-radiation frequency domain program, a nonlinear time-domain sea-keeping program and a FE solver. Extreme load analyses are perfomed for various dominant loads cases depending upon ship type. For various dominant load cases an equivalent regular wave is derived following Equivalent Design Wave (EDW) approach. These EDWs are used in nonlinear time domain simulations to compute the equivalent loads which the ship may experience during its entire design life. Finally, computed loads,motions and hull outer pressure are tranferred to FE model for both global and local structural analysis checks.

IRS have in-house developed software to perform sea-keeping analysis in both frequency domain (IRSPEED) and time domain. The load transfer and post process of structural analysis is performed using the in-house developed tool .