Building construction is an ancient human activity. It began with the purely functional need for a controlled environment to moderate the effects of climate. Constructed shelters were one means by which human beings were able to adapt themselves to a wide variety of climates and become a global species
2. Introduction
Building construction is an ancient human activity. It
began with the purely functional need for a controlled
environment to moderate the effects of climate.
Constructed shelters were one means by which human
beings were able to adapt themselves to a wide variety
of climates and become a global species
3. Precasting/Prefabrication
• Prefabrication is the process of assembling components of a
structure in a factory or other manufacturing site and transporting
these complete or sub assemblies to the construction site.
• The work is carried out in two stages.
1. Casting, curing
2. Transportation and erection in process
6. Concept of Precasting
1. Producing large quantity of structure and shipping them to
site
2. Independent of weather condition
3. Hardened before being used on site
4. Casted according to the required size and shape
5. Casted in the factory conditions or controlled weather
6. Casted in the moulds
7. Precast Components
• Precast beams
1. Internal beams
• support for the slab on the both sides
• Used Internally
2. External beams
• Support for the slab only in one side
• Used on the edges of structure.
13. Precast Construction System
1. Large panel system(fig.1)
2. Frame system(fig.2)
3. Slab column system(fig.3)
Fig.(1) Fig.(2) Fig.(3)
14. Connection between precast
components
There are three types of connection to
connect precast component with each other.
1. Column to column connection.
2. Beam to column connection.
3. Slab to beam connection.
15. Column to column connection
Metal bearing plates and embedded anchor bolts are cast into the ends of the columns.
After the columns are mechanically joined, the connection is grouted to provide full
bearing between elements and protect the metal components from fire and corrosion.
16. Beam to column connection
Beams are set on bearing pads on the column corbels. Steel angles are welded to metal
plates cast into the beams and columns and the joint is grouted solid.
17. Slab to beam connection
Hollow core slabs are set on bearing pads on precast beams. Steel reinforcing bars are
in inserted into the slab keyways to span the joint. The joint is grouted solid. The slab
may remain untopped as shown, or topped with several inches of cast in place concrete
19. Why precast not cast in situ ?
• Quality can be controlled and monitored much more easily
• Weather is eliminated as a factor-you can cast in any
weather and get the same results
• Less labour is required and that labour can be less skilled
• On site, precast can be installed immediately
• The precast structures can be dismantled, when required
and they can then be suitably used elsewhere.
