Effectiveness and robustness of braced‐damper systems with adaptive negative stiffness devices in yielding structures

Abstract This study applied adaptive negative stiffness devices in the application of braced‐damper systems to propose an adaptive negative stiffness amplifying damper (NSAD), and investigated its effectiveness and robustness for controlling the inelastic seismic responses of yielding structures. The adaptive stiffness behavior of the proposed NSAD perform negative stiffness and damping magnification effect within a certain displacement threshold, thus controlling both structural acceleration and drift at elastic stage; when subjected to strong earthquakes, the proposed NSAD would adaptively develop positive stiffness, which limits the inelastic deformation of yielding structures. A set of nonlinear seismic spectra are established for responses including acceleration, ductility, energy dissipation, and residual deformation. Numerical results validated that the proposed adaptive NSAD is effective for both elastic and inelastic structures. In addition, influences of key parameters like flexible support, negative stiffness ratio, and displacement threshold ratio (ratio of displacement threshold to yielding displacement), are carefully studied. From the point of controlling both acceleration and ductility demands of inelastic structures, the displacement threshold ratio is recommended to have a value close to a unit; typically, a reasonable upper limit of displacement threshold ratio is recommended to be lower than 1.5 to avoid amplifying residual deformation.