PERMANENT MAGNET-BASED TUNED MASS DAMPER DEVICE FOR DETERIORATION CONTROL OF BRIDGE EXPANSION JOINT

摘要

A permanent magnet-based tuned mass damper device for deterioration control of a bridge expansion joint, the device comprising a mass block (1), permanent magnets (5) arranged on inner and outer sides of the mass block (1) and coated with a graphene coating, an inner copper plate (4), an outer copper plate (3), and a number of springs (2, 6, 7). The inner copper plate (4) and outer copper plate (3) have fixed positions. The mass block (1) is suspended from an upper fixing plate (9) of the device via the spring II (6). Horizontal vibration of a box girder causes the mass block (1) to swing, and the inner copper plate (4) intercepts field lines of an induced magnetic field generated by the permanent magnet (5) on the inner side of the mass block (1). Vertical vibration of the box girder causes the mass block (1) to move vertically, the outer copper plate (3) intercepts field lines of an induced magnetic field generated by the permanent magnet (5) on the outer side, and the vibration energy is dissipated by means of resistance heat generation of the copper plate. The device has a simple structure and is convenient to install, avoids the leakage problem of conventional viscous liquid dampers, significantly increases service life of dampers, and improves damping efficiency of the device. In addition, the damper device can control both horizontal and vertical displacement of a girder end, thus greatly reducing the probability of a corner of the girder end distorting or damaging an expansion gap, and controlling the start and progress of a deterioration process of an expansion gap.