Beams

The cross-section of the beams is standardized. The prestressing force and the beam length is adapted to each specific project. The units are provided with details and inserts for connections and other specific purposes – for example, for fixings, openings, etc.

 

Purlins are used as secondary beams for roof structures with light roof cladding. The distance between the portal frames is maximum 12 to 16 m. The units are in prestressed concrete. The fire resistance is normally 60 minutes. The standard cross-section is shown in the figure below.

Purlins are mainly used in industrial storage buildings where light roof coverings such as steel sheet decking, corrugated slabs, cellular concrete slabs, etc. are used. The span of these elements is generally limited to about 3 to 5 m and secondary prestressed beams are needed to bridge the distance between the portal frames. The latter can be at larger distances, up to 12 and even 16 m. In this way large open halls can be constructed in an economical way.

 

 

Rectangular beams are mainly used for roof structures, and also for floors with composite action. They are usually in prestressed concrete, although classical reinforced concrete is possible. Standard sections are shown in the table below.

 

Composite floor beams

R-beams may be designed composite with the floor to enhance the flexural and shear capacity, fire resistance and stiffness. The main advantage of a composite beam structure is that it permits less structural depth for a given load-bearing capacity.The breadth of the compression flange can be increased to the maximum permitted value, as in monolithic construction. For composite action with
hollow core floors, the collaborating section is through the unfilled hollow core. This comprises only the top and bottom flanges of the slab. Detailed information about the load-bearing capacity is available from the technical department.

 

 L-beams & inverted T-beams

L-beams and inverted T-beams are typical floor beams because of the reduced overall structural depth. The beams are in prestressed or reinforced concrete. Standard Consolis’ cross-sections are shown in the table below. The boot width is governed by the adequate floor slab bearing distance.

 

Changes in floor level may be accommodated by either an L-beam or by building up one side of an inverted T-beam, as shown in the figure. If the change of floor level exceeds about 750 mm, a better solution is to use two L-beams back to back and separated by a small gap for easier site fixing.

 

 

SI-beams with variable height are particularly suited for roofs with large column free spans - for example, in industrial halls. The I-shaped cross section is typical for prestressed beams. The slope of the top face is 1:16.

 

 

I-beams are used for flat and sloped roof structures and for floor beams with heavy loading and large spans. The beams are in prestressed concrete and the fire resistance is, according to Eurocodes, up to 120 minutes.