Experimental Study on the force transfer mechanism at the R/C connection surface with post-tension force to develop the soft-landing base-isolation system

摘要

The authors are developing a new retrofitting system for relatively low seismic performance existing buildings, especially for soft-first-story buildings. The new column, which has the base-isolation system at its middle height, is attached to the existing column by the compression force with the PC bars. The existing column will fail in shear during an earthquake, and then the building becomes to be base-isolated. One of the big advantages of this system is that the retrofitting cost can be low compared to the conventional base-isolation retrofitting technique, since the existing columns do not have to be cut prior to an earthquake, which costs a lot. However, the vertical and lateral loads need to be transferred from the existing column to the newly attached column through the connection surface by the friction. In order to design the post-tension force required to the PC bars (the compression force required to the connection surface), the force carrying mechanism at the connection surface under the vertical and lateral loads needs to be studied. Therefore, a series of experimental tests were conducted to propose and verify a connection design criteria.