1. Classification of connection methods proposed by the United States
The United States Unified Building Code (UBC97) of 1997 simplifies the framework connection into two categories: monolithic connections and strong connections. The so-called integral connection is to infuse the prefabricated members with the prefabricated members, or the joints of the prefabricated members and the cast-in-place members with cast-in-place concrete. The so-called "strong connection" means that the joint portion of the prefabricated member has strong bending resistance. When the elastoplastic deformation occurs in the specified nonlinear region in the member under earthquake action, the joint portion can still maintain elasticity. The practice of strong connection is divided into column face connection, column-column connection, anchoring and splicing.
According to the US NEHRP (National Earthquake Hazards Reduction Program) 2000 specification, the precast concrete frame connection can be divided into an equivalent cast-in-place connection and a fabricated connection. The commonly used equivalent cast-in-place connection has a post-cast integral connection and a pre-stressed splicing connection. Commonly used assembly nodes include solder joints and bolted joints.
2 New Zealand proposed connection classification
New Zealand divides the connection form of framework nodes into four types:
1) Cast-in-place concrete columns and precast concrete beams, prefabricated slabs are placed on prefabricated beams, and the ribs are placed on the surface of the beams and slabs, the core of the beam-column joints, and the pillars of the lower layer, and finally the concrete is poured. Classified as a wet connection.
2) The prefabricated continuous beam passes through the cast-in-place or prefabricated column. This method uses a large number of prefabricated components and avoids the arrangement of steel bars and concrete in the small space of the beam-column joints. Classified as a wet connection.
3) Prefabricated T-shaped and double-crossed members, the connection is mainly connected by welding or mechanical sleeve. Classified as a dry connection.
4) The prefabricated prestressed concrete members apply pre-tensioning to the prefabricated U-shaped thin-walled beams, and the post-tensioned thin-walled beams are used as the permanent bottom mold to reproduce the concrete. Classified as a dry connection.
3 Classification of connection methods proposed by China
According to the "Technical Specifications for Prefabricated Monolithic Reinforced Concrete Structures" promulgated by the Shenzhen Housing and Construction Bureau in 2009, the connection methods of precast concrete are classified as: connection of laminated beams, connection of columns, shear walls, connection of laminated plates , the connection of the stairs, the connection of the prefabricated exterior wall panels. Among the above methods commonly used are: cast concrete, mechanical straight anchor, steel narrow gap arc welding, molten groove strip welding, extrusion sleeve, sleeve injection, lock nut sleeve and so on.
4 Precast concrete connection
In precast concrete, the connection method determines the overall stability of the structure, so the study of the joint part is often the most important. The connection of the joints mainly includes the connection of the beam and column and the connection of the wallboard. Due to the different specifications of various countries, the classification of connection methods is also different. From the construction methods, most of them belong to dry connection and wet connection. Dry connection, that is, the connection method of the dry operation, the concrete is not poured when the connection is made, but the steel plate or other steel parts are implanted in the connected components, and the connection is achieved by bolting or welding; wet connection, ie wet operation The connection, when pouring concrete or cement slurry, is anchored. The following author discusses the connection of beams and columns in the frame structure and the classification of the connection method of the wall