Cyclic Horizontal Loading Tests of New Connection Systems Using a Single Anchor Bolt for Steel Roof Bearing

In Japan, not a few gymnasia have been damaged in every major earthquake, i.e., the 1995 Hanshin quake, the 2011 Great East Japan earthquake, and the 2016 Kumamoto earthquake, even though these facilities were designated specifically as disaster shelters. One major structural type of gymnasium is a steel roofing structure supported by reinforced concrete frames. An exposed-type connection is mostly adopted as a steel roofing structure bearing connection. During earthquakes, not only the steel roofing structure but also the RC frame surrounding an arena tends to deform toward the out-of-plane direction independently. Consequently, the roof bearing connections tend to be damaged by ruptured anchor bolts and by concrete breakout because of a lack of edge distance between the concrete surface and the embedded anchor bolts. To increase the shear strength of the connection, it is proposed that an anchor bolt be arranged at the center of the RC column and be stiffened by welding steel plates to prevent its flexural yielding. A series of static tests was conducted, with results showing that the ultimate shear strength of conventional connections is determined by concrete breakout, whereas those of the proposed connection exceeded the design shear strength of the RC column.