Abstract
An optimization approach is presented for design of a tuned mass damper called TD-TMD for three-directional seismic response reduction of structures. The mass damper consists of a viscous damper and a mass connected by flexible springs. By utilizing the flexibility of springs, the movement of the mass in three-directions and the elongation of viscous damper are amplified, and the vibration energy of the mass is effectively absorbed by the viscous damper. The TD-TMDs are attached to a latticed roof and its seismic responses are compared with those with conventional single-directional dampers. The objective function of the parameter optimization problem is the mean norm of the response displacements at the nodes of the roof. The bounds of parameters are determined by solving a auxiliary nonlinear programming problem to maximize the minimum deformation of the damper against static loads of various directions. The parameters are discretized into integer values, and approximate optimal solutions are found using a local search combined with pure random search that generates efficient intial solutions.
