Precast concrete frames involve an entire structure being fabricated off-site.
FP McCann manufactures three main types of precast frame construction:
- Portal Frames
- Column and Beam
- Crosswall Construction
Precast Portal Frames
Precast portal frames can be defined as two-dimensional rigid frames that have a rigid joint between the precast column and beam. The precast beamforming the roof at the top can be pitched or sloped. The main objective of this form of design is to reduce the bending moment in the beam, which allows the frame to act as one structural unit. Portal frame construction is suitable to use for wide span, single-storey buildings such as sheds or low-rise buildings with multiple floors such as warehouses.
FP McCann’s precast columns are available in a variety of sizes and shapes, including circular, square, rectangular or oval to suit all specifications. They may be single or double-storey height. Connections may be made via a base plate to the column or by reinforcing bars projecting from the precast unit, or set into a preformed hole in a foundation block and grouted into position. Foundation connections available include cast in base plates, dowel tubes or projecting bars.
- FP McCann manufactures a range of precast concrete beams including
- Ground beams – span between foundations or bases to support brick/ blockwork
- Spandrel beams- span between columns around the perimeter of a building, providing load-bearing support to floor and roof loads
- Spine beams – span the length of a building, providing load-bearing support to floor slabs on either side
- Lintel beams – span above door and window openings, providing load-bearing support to the structure above
- Balcony beams – are beams cast with an integral balcony
- Raker beams – span between columns, providing structural support for terracing units and can be made to any size or length
Precast concrete frames are cast in the same way as precast concrete cladding, but as they are designed as structural elements, have heavier reinforcement than is required for non-structural cladding.
Benefits of using Precast Concrete Frames
- Speed pf construction is increased as follow-on trades can commence much earlier
- Quick installation since the structure is fabricated off-site
- Offsite construction enables a high standard of workmanship in factory conditions – reduces the potential for accidents and is not affected by weather or labour shortages etc.
- Wide variety of quality finishes achievable and concrete can be left exposed
- Maintenance-free – no need to paint or periodically replace beams as you would with alternative types of beams such as timber beams, which can rot, or steel beams – which can rust and corrode
- Fire-resistant – concrete has its own built-in fire resistance, which can also help to keep insurance costs down etc and there is no requirement for a site applied fire coating as with other systems
- Economical – lower total cost due to speed of construction, lower labour costs as welders or skilled workers are not required for installation; concrete frames are not as expensive as steel beams and have lower maintenance costs
- The high thermal capacity of concrete can reduce the demand for heating, ventilation and air conditioning, unlike alternative types of frames
- Flexible design – concrete can be cast into any shape, for example, arch-shaped beams, required to suit a variety of project plans and elevations.
- Low-rise and multi-storey offices
- Elevated car parks
- Retail, industrial and warehousing developments
Precast Concrete Car Parks
Precast multi-storey car park structures are designed and manufactured using several structural precast elements, including columns, beams, spandrels, stairs, lift shafts, hollowcore flooring slabs and wall panels. Due to their reduced self-weight, hollowcore flooring slabs can achieve clear spans of up to 16m, this reduces the requirement for vertical columns, creating better manoeuvrability and therefore reducing the risk of damage to vehicles and the car park’s structure.