Precast Walls
Cross Wall Construction - Housing, Apartments, Student Accomodation, Hotels
Cross wall construction, using precast floors and load bearing walls, is normally associated with multi-.jpg "Apartments Cross Wall")
storey buildings. This type of construction is ideal for buildings of a cellular structure, for example hotels, offices, student accommodation, housing and apartment developments.
Cross wall multi-storey structures consist of precast floors and load bearing walls, where the walls are designed as the means of primary support. Longitudinal stability is achieved by external wall panels and/or diaphragm action involving the floors and roof, which are connected back to lift cores or staircases, which are also formed by precast wall panels. The system provides a structurally efficient building with main division walls offering a high degree of sound insulation between adjacent dwellings, offices, etc.
One of the advantages of cross wall construction is that an early "dry box" working construction is created, allowing subsequent trades access to achieve a fast build programme using the minimum of wet trades. These walling systems can produce buildings in excess of 20 storeys. However, in the Irish context, structures greater than 10 storeys are rarely required, primarily due to planning restrictions.
Precast Car Park Frame & Deck.jpg "Car Park")
Precast frames are commonly used for basement or roof top car parks, whether independent, free standing or forming part of a mixed development. The majority of car parks in Ireland are concrete column and deck structures. These are specialist structures, but their layout is ideally suited to a precast solution.
A typical layout allows a standard bay size in the region of 15.6m x 7.2m which is generally the optimal solution. The 7.2m distance relates to the beam or "spandrel" span and the 15.6m dimension will suit 400mm thick hollowcore floor units. The use of deep hollowcore units generally negates the need for inboard columns which inhibit vehicle manoeuvrability and obstruct the opening of vehicle doors. Spandrel panels are combined beam and wall panel units. Spandrel panels also act as internal vehicle barriers or as external vehicle barriers when used at the perimeter of the structure.
Mixed Construction
Precast concrete is particularly suited to mixed construction because it readily combines with virtually all.jpg "Industrial Precast Wall Panels")
other commonly used construction materials. Tried and tested standard details for the interfacing of concrete and other construction materials are well established. Combining precast concrete with steel, cast in situ concrete, masonry and glass maximises the benefits of each material. The most economical result can sometimes be achieved by mixed construction methods. In some projects, the designerís requirements can only be met by using mixed construction.
Mixed construction requires a considered approach. Nowadays there is increased emphasis on fire resistance, acoustics, low maintenance and aesthetics. These properties are substantially inherent in concrete, but are not necessarily inherent in substitute materials. Steel, for example, needs substantial fire protection. The substitution of precast elements with steel must be carefully appraised.
A good example of mixed construction is steel frame and precast concrete wall panels and floors.
Using precast as the dominant form of construction in mixed construction reduces construction time, shuttering and wet trades. The number of reinforcing bars is greatly reduced and site safety is greatly improved by the installation of precast floors which act as safe working platforms. Since most of the construction is carried out in the factory, there is less down-time and noise disturbance. The number of operatives on site is also greatly reduced.
