A study has been undertaken to show the inadequacy in the existing design methods after observing the satisfactory performance of geosynthetic reinforced soil structures (GRSSs) originally designed for carrying less load than what they experienced during the 1994 Northridge, California and 1995 Kobe earthquakes. In order to facilitate a general approach towards understanding the behaviour of geosynthetics under different loading regimes, i.e. under single stage loading and multi stage loading, the ‘strain envelop’ concept has been developed and presented. On this basis, an approach for design of GRSSs under sustained plus short term loading regime is also suggested.