19-09-2014, 02:13 PM
PRECAST CONCRETE CONSTRUCTION
PRECAST CONCRETE.ppt (Size: 353.5 KB / Downloads: 479)
INTRODUCTION:
Every construction material & system has its own characteristics which to a greater or less extend influence the layout, span length, construction depth, stability system, ect. This is also the case for precast concrete , not only in comparison to steel, wood, & masonry structures, but also with respect to cast in-situ concrete. Theoretically, all joints between the precast units could be made in such a way that the completed precast structure has the same monolithic concept as a in-situ one. However, this is a wrong approach & one, which is very labour intensive & costly. If the full advantages of precast concrete are to be realized, the structure should be conceived according to its specific design philosophy:
long spans, appropriate stability concept, simple details, ect. Designers should from the very outset of the project consider the possibilities, restrictions & advantages of precast concrete, its detailing, manufacturer, transport, erection & serviceability stages before completing a design in precast concrete.
Precast concrete frame
Precast concrete frames involve an entire structure being fabricated off-site. In addition, structural components can be supplied for incorporation into a structure on-site. Frames can simultaneously achieve both structural and decorative design requirements - a wide variety of mixes, colours and finishes can be accommodated. Architecturally-finished precast structures can be left exposed to exploit concrete's high thermal capacity in a building's "green" energy management system.
Disadvantage of precast concrete
System building is less flexible in its design concept than purpose-mode structures
Most design briefs can be fulfilled without too much modification to the original concept
Structural connection between the precast concrete units can present both design & contractual problems
CONCLUSION
Pre-fabrication has a great potential to respond to new market demands. Possible solution lie not only within the classical advantages related to working conditions, technology & speed of construction, but also in new developments of materials such as high performances & self-compacting concrete, buildings system such as mixed structures, manufacturing technology, automation, service integrated products & others