In the design procedure of geosynthetic reinforced-soil structures, the residual deformation during the service period of the structure is one of the key issues. To investigate the development of residual strain of polymer reinforcements, a series of load-controlled tensile tests was performed generating the following loading histories: a) continuous monotonic loading (ML) at a constant load rate; b) creep (or sustained) loading; and c) cyclic loading with controlled amplitudes and frequencies. Though it has been usually considered that residual straining during cyclic loading is due to the effects of time-independent cyclic loading history (i. e., as a function of the number of loading cycles; amplitude; and so on), it was found from this study that cyclic residual straining is due essentially to the loading rate effects caused by material viscous property. A non-linear three-component model originally developed for simulating the rate-dependent deformation of geomaterials (i. e., soils; and rocks) was modified to simulate the relationship between tensile load and strain for ML; creep; cyclic loading; and general loading histories obtained from the present study.