KDamper concept in seismic isolation of bridges with flexible piers

摘要

Contemporary seismic isolation systems for bridge applications provide (a) horizontal isolation from the effects of earthquake shaking, and (b) an energy dissipation mechanism to reduce displacements. Throughout the years many kinds of seismic isolation mechanisms have been developed, with two concepts being the most promising ones: the introduction of negative stiffness elements and the incorporation of an additional mass. The latter has led to the development of Tuned Mass Dampers (TMDs), engineering devices consisting of a mass, a spring and a viscous damper commonly used to suppress any undesirable vibrations induced by wind and earthquake loads. The negative stiffness behavior is primarily achieved by special mechanical designs involving conventional positive stiffness pre-stressed elastic mechanical elements, such as post-buckled beams, plates, shells and pre-compressed springs, arranged in appropriate geometrical configurations. Combining the beneficial characteristics of both concepts, a novel passive vibration isolation and damping concept is introduced, the KDamper. The KDamper is based on the optimal combination of appropriate stiffness elements, which include a negative stiffness element. The presence of the additional mass enables structural vibrating energy to be transferred from the structure to the device. The main advantage of the KDamper over other similar concepts including negative stiffness elements is that no reduction in the overall stiffness of the system is required.