Speed changing mass damper system for bridge shock absorption

The invention provides a speed changing mass damper system for bridge shock absorption and belongs to the technical field of passive control over bridge structures. The speed changing mass damper system comprises a tuning mass block, a gearbox, a spring, an energy dissipation device and a connecting piece, longitudinal displacement of a girder caused by earthquake force can be effectively reduced, and thus the bending moment of a cable tower is reduced. The horizontal connecting piece is arranged at the end of the girder and connected with the gearbox on an anchorage. The gearbox is a speed changing mechanism, and as for the speed changing mechanism, a rack is used for driving a gear. The tuning mass block moving vertically is arranged in the position of the anchorage and connected with the gear of the gearbox through a steel wire rope. The spring is connected to the lower end of the tuning mass block, and the rubber energy dissipation device is installed at the bottom of a slideway of the mass block. The kin