At present, no matter we are at home or abroad, the construction of reinforced concrete structure, reinforced by the basic connection is the mainly way of welding and mechanical connection.

Domestic and foreign steel joints in reinforced concrete construction abroad is used for a long period of time, but this way is the concrete implementation of joint grip, therefore, it waste steel. Nineteen seventies,industry developed countries such as the United States, Germany, France, and so on began the development of reinforced mechanical connection technology, all kinds of mechanical join techniques have emerged, such as upsetting rebar coupler, cold pressing rebar coupler etc..

Threaded connection technology does not need the workers have high technology, fast connection, but the strength of the steel connection strength is lower than the base material, easy to break joints; thread quality on-site processing of difference, drainage bolt tightening torque screw loose, have influence on the joint strength.