Isolation using negative stiffness

IITB Logo Manish Kumar
Assistant Professor

Department of Civil Engineering
Indian Institute of Technology Bombay, Mumbai

Negative Stiffness



Isolation using negative stiffness

Concept of vibration isolation using negative stiffness is not new. User can refer here, for discussion on negative stiffness. Conventionally, it has been used with small equipments, rotating at high speeds, attached to the floor, ceiling or wall. However, application of this concept in large scale civil engineering structures has still not found its way. Tests have been going on at University at Buffalo to see response of multistory buildings with negative stiffness isolator at ground floor. The idea is to apply an equal and opposite stiffness of certain floor to isolate it. This minimizes the inertia load transfer and reduction of seismic forces in case of earthquakes. At the same time, it poses the problem of large displacements, which is not desirable. Hence, viscous dampers are used to minimize the displacement. Viscous dampers with zero stiffness of the particular floor is very effective in decreasing the displacement of particular story.

Feasibility of this concept for structural engineering applications still needs to be confirmed and tests are going on to study the behavior of structures with negative stiffness isolators.