ABSTRACT
Semi-active resetable devices are an emerging and effective method of minimising structural degradation due to environmental loads. Of particular importance in implementing supplemental damping, such as resetable devices, is the ability to retrofit existing structures. However, supplemental damping also tends to increase base shear demand, limiting practical gains. The use of a two-chamber resetable device enables a control law to be used that adds damping only into quadrants 2 and 4 of the force-deflection plot, adding damping forces on the opposing diagonals to the structural force. Thus, base shear canbe reduced, creating significant potential for retrofit applications. The impact of off-diagonal 2–4 damping on the displacement structural response, structural force and total base shear is investigated through spectral analysis. The 2–4 control law is shown to be the only law that can reduce the structural force as well as the total base shear for a structure; a unique result. Off-diagonal damping equal to 100% additional stiffness reduced both the structural force and total base-shear by 20–35%. Therefore, semi-active enabled off-diagonal damping could be incorporated into large scale retrofit applications where present passive approaches have significant limitations.
