CLASSIFICATION OF BEAMS ACCORDING TO THEIR USE Beams according to their use are classified into seven types which are discussed below:

1. Lintel Beam2. Joists Beam3. Rafter Beam4. Purlin Beam5. Girt Beam6. Trimmer Beam7. Collar Beam

1.Lintel Beam : Lintel is a simple architecture where a horizontal member (the lintel—or header) is supported by two vertical posts at either end. This form is commonly used to support the weight of the structure located above the openings in a bearing wall created by windows and doors.

Use of lintel beam: Lintel beams are used as a support above the doors n windows. They transfer the load to walls and save doors n windows from direct load.

Disadvantages: The biggest disadvantage to a post and lintel construction is the limited weight that can be held up, and the small distances required between the posts.

2.Joists Beam: A joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor. It may be made of wood, steel, or concrete. Typically, a beam is bigger than, and is thus distinguished from, a joist. Joists are often supported by beams and are usually repetitive.

Calculation of depth of Joists: The wider the span between the supporting structures, the deeper the joist will need to be if it is not to deflect under load. Lateral support also increases its strength. There are approved formulas for calculating the depth required and reducing the depth as needed; however, a rule of thumb for calculating the depth of a wooden floor joist for a residential property is half the span in feet plus two inches; for example, the joist depth required for a 14-foot span is 9 inches. Many steel joist manufacturers supply load tables in order to allow designers to select the proper joist sizes for their projects.

3.Rafter Beam: A rafter is one of a series of sloped structural members (beams), that extend from the ridge or hip to the down slope perimeter or eave, designed to support the roof deck and its associated loads.

Design: A type of beam, which supports the roof of a building. In home construction, rafters are typically made of wood. Exposed rafters are a feature of traditional roof styles.

Applications: In many buildings, rafters have been replaced by engineered trusses (trussed rafters), normally because of span limitations and/or roof load (weight from above).

4.Purlin Beam: In architecture or structural engineering or building, a Purlin (or Purline) is a horizontal structural member in a roof. Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and/or the building walls, steel beams etc. The use of Purlins, as opposed to closely spaced rafters, is common in pre-engineered metal building systems and some timber frame construction.

Use of Purlin:

In lightweight timber roof construction under purlins were used to support rafters over longer spans than the rafters alone could span. Under purlins were typically propped off internal walls. For example, an 8 x 4 under purlin would support the center of a row of 6 x 2 rafters that in turn would support 3 x 2 roof purlins to which the roof cladding was fixed. In traditional timber truss construction purlins rest on the principal rafters of the truss. In all metal or mixed building roof systems, purlin members are frequently constructed from cold-formed steel, (or roll formed) C or Z sections. The Z sections can be lapped and nested at the supports which create a continuous beam configuration between the bays. When C and Z sections are used in wall construction are normal to call them girts.

5. Girt Beam: In architecture or structural engineering, a girt is a horizontal structural member in a framed wall. Girts resist lateral loads from wind and support wall cladding materials. Girts are supported by the columns and typically pass outside of one or more columns. The use of girts to support metal siding is common in pre-engineered metal building systems.

Use of Girt Beam: In metal building systems, girts are frequently constructed from cold-formed steel 'Z' sections in a manner similar to roof purlins. These sections can be lapped and nested at the supports which create a continuous beam configuration between the bays. An equivalent element in roof construction is a purlin.

6.Trimmer: In light-frame construction, a trimmer is a timber or metal beam (joist) that is installed perpendicular to floor or ceiling joists in order to allow an opening, such as a stairwell or dormer, to be formed.

It can also refer to a jack stud that supports a header above a window or door opening.

Traditionally, a stud which was less than full length was sometimes referred to as a cripple.

7.Collar Beam:

In architecture, a collar beam (also known simply as a collar) is a horizontal piece of timber connecting and tying together two opposite rafters.

Use of Collar Beam : It is used to connect the two Rafters with each other and it provides support to them .