Steel structure is an assemblage of different members such as beam, column, plate, which need to be fastened or connected to one another. The basic goal of connection design is to produce a joint that is safe, economical and simple. It is also important to standardize the connections in a structure and to detail it in such a way that it allows sufficient clearance and adjustment to accommodate any lack of fit, resist corrosion, it easy to maintain and provides reasonable appearance.

The most known connections are:
• Simple connection,
• Moment resistant connections,
• Beam-to-beam connections,
• Beam and column splices.

Simple connection

In the steel structure we can found different types of simple connections, be classified as follow:
• Lap and butt joints
This is the simplest joint. This kind of connection is often used to connect plates or members composed of plate elements. When two peace of steel are connected together by bolts or welds, the joint is called a lap joint (fig. 1). In butt connection the members to be connected are placed against each other and are bolted or welded together through the use of additional plates (fig. 2).

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• Truss joint connection
Typical truss joints use gusset plates in order to accommodate bolts. These gusset plates are connected to the members of the truss by means of bolts or welds using lap or butt joints depending on whether one or two angles (fig. 3).

• Clip and seating angle connections
In this connection the top cleat is provided for lateral or torsional restraint to the top flange of the beam and is bolted to the top flange (fig. 4).

• Web angle connection
A web angle connection better known as a angle cleat connection. One or two angles either to the flange or to the web of the supporting member cleats may be use and bolted to the beam web and to the supporting members (fig. 5).

• Flexible end plate connection
Consists of an end plate connected to the web of the beam, at the beam ends, by fillet welds. This plate is, in turn connected to the column flange or web by means of bolts (fig. 6).

Moment resistant connection

These kinds of connection are used in framed structures, where the joints are considered rigid. They are used only in non-sway frames where the lateral load resistance is provide by bracing shear walls. These kind of connections in which the connections are designed to transfer bending moments and shear or a combination of bending moment, shear, and axial force, may be grouped into the following: eccentrically loaded connections, t-stub connections and flange angle connections (fig. 7).

Beam to beam connection

The simple connection such as clip and seating angle connection, web angle connection and flexible end plate connection, discussed in the earlier sections for connecting beam to columns, can be adopted for beam to beam connections also (fig. 8).

Beam and column splices

For beam splices, each element of the splice is designed to do the work, the sections underlying the splice plates could do, if uncut. Plates on the flange should be designed to do the work of the flange, and plates over the web should be designed to do the work of web. The connections as discussed for beam may be adopted for columns splice also (fig. 9).