Steel structure fastener connection is a kind of connection method which can produce strong force through bolts, rivets and other fasteners, so as to connect steel structure connectors into one.The connection of fasteners needs to be drilled, which weakens the cross section of steel members to a certain extent. Sometimes, auxiliary connectors must be added in the structure, so the structure is more complex and more materials are used.However, the fastening tools and technology of steel structure fastening connection are relatively simple, processing, disassembly and maintenance are convenient, easy to implement, and the progress and quality are easy to ensure. Therefore, fastener connection is widely used in steel structure installation and connection, because rivet connection is less used in building steel structure construction.

1、 Common bolt, the common grade of pain bolt in building steel structure is Q235, which is rarely made of other grades of steel. The common bolt used in building steel structure is generally hexagonal head bolt.The mark of the bolt is usually MD * Z, where D is the bolt size (i.e. diameter) and Z is the nominal length of the bolt.The general specifications of common bolts are M18, M10, M12, M16, M20, M24, M30, M36, M42, M48, M56 and M64.According to the form, ordinary bolts can be divided into hexagon head bolts, stud bolts and countersunk bolts, and according to the accuracy, they can be divided into three grades: A, B and C.The bolts used for steel structure connection, unless otherwise specified, are generally made of ordinary coarse grade C bolts.

2、 High strength bolt is a kind of special bolt made of high quality carbon steel or low alloy steel.Grade 8.8 high strength bolt is made of 35 steel and 45 steel after heat treatment. The high strength bolt connection has the advantages of simple installation, high bearing capacity, good stress performance, safety and reliability.High strength bolt connection has become a new type of structural connection after rivet connection, and has been developed into one of the main means of steel member connection.High strength bolts can be divided into large hexagon head and torsion shear type, and can be divided into 8.8 grade, 10.9 grade and 12.9 grade according to the performance grade. At present, the large hexagon high strength bolt connection pair used in China is composed of a bolt, a nut and two washers (one washer on both sides of the screw head). The torsional shear type high strength bolt connection pair consists of a bolt, a nut and a cushion Circle composition.The performance grade of bolt, nut and washer should match with each other when they constitute the connection pair.