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CLASSIFICATION OF INDUSTRIALISED CONSTRUCTION

By Barry Long,2014-01-04 18:32
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CLASSIFICATION OF INDUSTRIALISED CONSTRUCTION

FIGURE 9. Arrangement of tie beams.

    Earthquake: South-east Europe, the Balkans, Turkey, Cyprus and the Kafkas region are on an earthquake belt and very frequently experience earthquake disasters. Thus it is very important that the construction systems are safe in respect to earthquakes. Earthquakes are graded with numbers up to 12. Earthquakes with 5 6 forces may cause minor defects

    on buildings. However 7 9 forces may cause complete destruction

    depending on the strength of the buildings. The destruction lessens as the distance to the centre of the earthquake increases.

    Earthquake precautions should be considered not only on the buildings themselves but also on the areas around buildings. Street width, distance between the buildings and the green areas should also be considered from the point of earthquake security.

    If the building plan is too complex it may be divided into simpler forms by earthquake joints (Figure 8). Actually, not only the building plan but also the section, structure and the mass should be solved regularly without excessive openings, cavities or overhangs in earthquake areas.

    In skeleton building systems the lower parts of the columns above the foundations should be connected to each other with tie beams (Figure 9). Special care should be given to the connection systems of prefabricated columns, beams, floor and wall components.

    In load bearing building systems there should be cross walls whose spans do not exceed the levels given by the “Earthquake Guide”. There should not be any opening less than 1.5 m distance to the corners of the building.

    It is necessary to define the terms “building material”, “building component” and “building element” here. Building materials are

    shapeless materials like cement, sand, steel, timber etc. When a building

material is formed as a distinct unit with a shape, it is called “building

    component”. Thus a brick, a steel profile or a door is a building component. Building components can be of three types; “profile building

    component”, “unit building component” and “composite building

    component”. Each part of a building with special function like wall, floor, roof, foundation is called “building element”.

CLASSIFICATION OF INDUSTRIALISED CONSTRUCTION

    Industrialised construction systems can be classified according to various characteristics. One of the classifications depends on whether the elements cast in situ or of prefabricated units.

    A) Wet Systems: Wet systems are those which are produced by

    casting the elements to the moulds on building.

    B) Dry Systems: Dry systems are those which are produced by the

    assembly of prefabricated units without the use of any liquid type

    jointing material.

    The second classification depends on the degree of industrialisation. A) Developed Traditional Construction Systems: In these systems

     industrialisation principles are applied to traditional construction

     systems. Like tunnel formwork, sliding formwork, slab lifting etc. B) Semi Industrialised Construction Systems: The elements are

     produced on site or at temporary workshops.

    C) Fully Industrialised Construction Systems: In these systems all

     the units are produced at the factory and assembled on site.

    A third classification depends on the weights of the building components and elements.

    A) Heavy Industrialised Construction Systems: In these systems

    units are heavy and large like floor or wall panels.

    B) Light Industrialised Construction Systems: In these systems

     components are made of small and light units.

    A fourth classification depends on whether the building components are interchangeable or not.

    A) Closed Industrialised Construction Systems: In these systems all

     the components of a particular system are produced by one

     company.

    B) Open Industrialised Construction Systems: In these systems the

    components of a particular system are obtained from different

    companies which utilise the same joint design and which have

    dimensional coordination between each other.

    Another classification is made according to the structural systems of the building. There are also sub systems of this classification (SEY & TAPAN, 1987).

    A) Skeleton Systems: In which the columns and beams carry the

     building load.

     A1) Column-Beam-Floor Systems: In which the building loads are

     conveyed from floor to beam and from there to the columns.

     A2) Frame Systems: In which the structure of the building is composed

     of frames and the floors.

     A3) Column-floor Systems: In which the loads are conveyed directly

     from the floor to the columns.

B) Load Bearing Panel Systems: In these systems wall and floor

     panels carry the building load.

     B1) Large Panel Systems: The sizes of the panels are as large as the

     size of the space they enclose.

     B2) Small Panel Systems: The vertical and the horizontal building

     elements of a space are composed of more then one panel. C) Cellular Systems: In which the building is composed of cell units

     produced at the factory and assembled on site.

     C1) Block Type Cellular Systems:

     C2) Panel Block Type Cellular Systems:

     C3) Skeleton Block Type Cellular Systems:

     Cellular systems can also classified as Open Cellular and Closed

    Cellular Systems. In open cellular construction systems one space is made of more then one cell. In closed cellular construction systems one space is made of one cell only.

TUNNEL FORMWORK CONSTRUCTION SYSTEM

    In tunnel formwork construction system, reinforced concrete is used as the structural building material. The system provides the casting of both the load-bearing walls and the floor under a single process. This is a developed traditional system and it is a wet construction technique (FIG 10). It is a very fast construction technique and it is very suitable for medium high-rise buildings.

    In this system special steel formworks are used. Once the formwork for a storey is set, the reinforced concrete walls and the floor are cast continuously. Thus a building which is monolithic in nature is obtained and it is very durable against horizontal stresses. The system has two variations depending on the type of the tunnel formwork used.

A) Semi-tunnel formwork,

    B) Full tunnel formwork.

    Two semi-tunnel formworks are connected to each other side by side to form a complete tunnel formwork. Both the semi and full tunnel formworks can be connected on ends to form tunnel formworks for deeper rooms (Figures 11 A, B, C, D, E, F). Tunnel formworks are made of 34 mm thick sheet steel, have adjustable and wheeled elements. Tunnel formworks constitute moulds both for the wall and the floor of a building. Additional steel formworks for the side ends of the building and balconies or for working platforms are also used. After assembling the formwork; reinforcement, electrical and the other service pipes are positioned and the concrete is cast. The openings like doors, windows and chimneys are provided by the use of reservation moulds. Generally a curing method is applied for the fast setting of the concrete. Then the formworks are taken out of their position, cleaned, oiled, and positioned for an upper floor.

    The length of the tunnel formworks are 62.5, 125 and 250 cm. By jointing these formworks up to 1250 cm total length can be obtained depending on the lifting capacity of the crane. The widths of the formworks are 105, 135, 165, 195, 225, 255, 285 cm. The widths up to 570 cm can be obtained with the different combinations of these seven sizes. These combinations can provide many different room sizes. The heights of the formworks are between 230 to 300