Swinging motion control of suspended structures : principles and applications

This paper discusses the development of non-linear differential equation modeling and characteristic analysis of control force for motion control of suspended structures, and proposes an innovative passive control system for suppressing swinging motion of similar structures. Based on the classical Lagrangian principle, the system EOM can be established with respect to two basic motion modes: planar motion and swinging motion. The analytical results indicate that different control systems should be considered owing to the diverse motion characteristics of the suspended system. Furthermore, theoretical results show that the tuned mass damper (subsequently abbreviated as TMD) cannot be used for swinging motion control, due to the coupling effect between linear stroke of TMD mass and angular velocity of suspended structure. Then, based on thorough numerical analysis, the concept of tuned rotary inertia damper (subsequently abbreviated as TRID) control system is proposed, and the differential equations of motion, denoting the motion law of the whole system, are studied. In addition, optimization issues of TRID control are equivalent to the classical optimization problem of TMD control. At last, conclusions were extended to vibration or motion control of typical civil engineering structures, such as high-rising tower structures with prior bending deformation characteristics and long-span bridges with rotation vibration characteristics. Once the structural motion or vibration is similar to the single pendulum or inverted pendulum, the planar TMD control system will lose its effectiveness and the innovative TRID system should be considered for suppressing swinging motion of such structures.