A new hysteresis model is developed for thin Steel Plate Shear Wall (SPSW) systems which incorporates cyclic and in-cycle deteriorations. The model is implemented into the OpenSees software and is validated against a number of experimental evidences. Seismic response sensitivity of SPSW system to the hysteretic model characteristics is evaluated, afterwards, using three code-conforming SPSWs with different heights. The 15 variant models developed for each frame using different combinations of deterioration parameters are subjected to incremental dynamic analysis. The sensitivity of the derived median collapse capacities, expressed in Sa(T1) terms, to the “cyclic” and “in-cycle” deterioration parameters are finally assessed.