With the emergence of high-rise building, large-span space and special structures, the application of building rebar is developed towards big diameter, dense and high strength. The traditional rebar splicing technology such as welding and lapped splicing can not meet the requirements commendably in strength and saving cost. In this condition, as a new rebar connection technology, parallel thread connection technology, especially the upset forging parallel thread connection technology is now more and more adopted in projects.
