TYPES OF PRECAST COMPONENTS IN A BUILDING:
The figure below shows the basic precast structure. The numbers of different types of components in these structures over the years have become very large. But following figure shows the major types of precast components in a building.
There are two main categories of beams:
- Internal beams – where floor loading is approximately symmetrical
- External beams – where floor loading is predominantly non-symmetrical.
Fig: Internal beams
Fig: External beams
For structures of five storeys or less, each column will normally be continuous to the full height of the building. For structures greater than five storeys two or more columns are spliced together.
The main types of precast columns are:
- Edge columns – symmetrical in one direction.
- Internal columns – symmetrical in all directions.
- Corner columns – not symmetrical at all.
Precast floor slabs:
The main types of slabs are used in the precast frames are:
- Hollow cored slab
- Double tee slab
Precast concrete walls serve two functions:
- As walls or boxes surrounding staircases and lift shafts.
Walls may be classified as infill or cantilever:
- Infill walls rely on contiguous composite action with the beam and column frame.
- Cantilever walls or boxes act as deep beams to which the frame is attached.
Three options are available for precast staircases:
- A single precast unit containing all the flights and landings
- Separate precast flights and landings
- Parts of the flights and landings are made in one piece.