Negative Stiffness Brace Device for Structural Systems: Analytical and Experimental Study

In this study, negative stiffness brace (NSB) device composed of a series of pre-compressed springs, gap-spring assemblies and links to achieve the desired negative stiffness behavior suitable for application in structural systems is investigated analytically and experimentally. NSB achieves a high force magnification by using the geometry, harnessing the spring force at both the ends and through the usage of multiple pre-compressed springs and links, in series. Series arrangement significantly reduces the stiffness requirements of the pre-compressed springs. NSB has a compact arrangement of components, which reduces space consumption as well as allows easy installation. In this study, the analytical model describing the behavior of the NSB is presented and the effect of various parameters on the behavior is investigated. A scaled NSB device is tested and experimental results of the behavior of the NSB are presented and used to validate the analytical model. Negative stiffness devices and supplemental damping devices have been recently studied extensively for the protection of structural systems subjected to wind and seismic excitations since the combination can significantly reduce accelerations and inter-story drifts, and base shears. NSB with supplemental dampers has significant potential for application in structural systems.