A series of bidirectional loading tests were conducted on a high friction type sliding rubber bearing. Tests were conducted under horizontal bidirectional loading and constant or fluctuant vertical loading. Regardless of the vertical loading methods, the maximum shear strain under bidirectional loadings increased approximately 40%-50% compared to nominal shear strain. Reflecting mechanical characteristics of the bearing, the analytical model of elastic sliding bearings was proposed. This model accurately represented force-displacement relationships under horizontal bidirectional loading and constant or fluctuant vertical loading.
The study involved proposing a tuned mass damper (TMD) system with a novel mechanism for supporting the mass, which is called the two‐phase support (TPS) mechanism. The system can make the configuration of a TMD compact with low frictional characteristics; the TMD can operate effectively during not only earthquakes, but also strong winds in the interior of an existing building. The TPS mechanism consists of multi‐stage rubber bearings (MRBs) and linear motion bearings (LMBs). Each LMB is equipped with a vertical clearance of a few millimeters in its block portion. LMBs do not support the mass under small deformations of the MRBs so that the TMD can achieve low friction. Conversely, LMBs support the mass under large deformations of the MRBs, hence slender MRBs do not buckle and function as horizontal springs. We describe two types of experiments, namely experiments using a small specimen and tests using an actual TMD with a large mass of 7000 kN. We verified that the slender MRBs functioned without buckling and stably as restoring springs through the TPS mechanism even when large deformations occurred. Furthermore, we confirmed that the frictional and dynamic characteristics of the TMD agreed with the desired ones.
This report presents experimental and analytical study on progress to the falling down of suspended ceilings without seismic bracing, and the effect of earthquake-resistant connection parts. In the experiments, the ceiling showed high compression buckling stress, but its restoring force had slip-type characteristics. It represented that the factor of the falling down was unfastening connection parts, and the expansion of screw holes.
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