Earthquakes have the potential to cause large-scale destruction of civil infrastructure often leading to significant economic losses or even the loss of human life. Therefore, it is vital to protect civil infrastructure during these events. Structural vibration control provides a method for mitigating the damage to civil infrastructure during earthquakes by absorbing seismic energy from the structure. Semi-active control has emerged as an attractive form of structural control due to its effectiveness, inherent stability, and reliability. One semi-active control device particularly effective in reducing the response of civil structures subject to near-field earthquakes is the resetting semi-active stiffness damper (RSASD). Substantial research has been conducted to develop the RSASD and demonstrate its control performance. However, like other semi-active control technologies, the RSASD relies on a multi-component feedback control system that is subject to reliability issues. The purpose of the proposed research is to develop a novel resettable stiffness system that is capable of achieving a similar control performance to the RSASD, but with fewer feedback components. The resulting device, the resetting semi-passive stiffness damper (RSPSD), will offer increased reliability without compromising effectiveness. The objective of the present work is to present the concept for the RSPSD, develop a mathematical model describing its resetting, identify critical design parameters, and then evaluate its control performance for single-degree-of-freedom structures subject to an earthquake ground motion. Numerical results indicate that the RSPSD is capable of comparable control performance to the RSASD for the structures and earthquake ground motion considered.