Prefabricated Structure and its installation process

Construction industry is growing day by day, whereas free space for material is reducing dayby day. Prefabricated structure provide a way through. Prefabrication is method in which structural members are built at industry and then transferred to site.

1. PRE-FABRICATED STRUCTURES 1

2. What We Are Going To Learn What is mean by Prefabricated structure? Concept of prefabricated structure. Prefabrication & its components. Advantage and disadvantage of prefabrication.

3. What is prefabrication? Assembling components of a structure in a factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The work is carried out in two stages, manufacturing of components in a place other than final location and their erection in position. 3

4. Stages of pre fabrication 4 The Prefabrication as defined will be done in two stages Manufacturing at factory condition and erection of components at the required location. This requires certain stages of preparation. They are Casting. Curing. Transportation and erection.

5. Casting 5 Precast components are casted with controlled cement concrete in moulds of required shape and sizes. The vibrator is used to vibrate concrete and this removes any honeycombing inside the components .

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7. Curing After 24 hours of casting, the casted components are released from the mould and transported to curing tanks. Certain special components like railway sleepers where high strength is required are steam cured. 7

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9. Transportation and erection After complete curing is done the components are transported to the site with heavy trucks and erection will be done using cranes with skilled labour force .

10. Prefab building components Columns : A column is a vertical member carrying the beam and floor loadings to the foundation. It is a compression member and therefore the column connection is required to be proper. The main principle involved in making column connections is to ensure continuity and this can be achieved by a variety of methods. 11

11. Column to Column Connection

12. 13 Beams: - Beams can vary in their complexity of design and reinforcement from the very simple beam formed over an isolated opening to the more common encountered in frames where the beams transfer their loadings to the column . Column and beam reinforcement, generally in the form of hooks, are left exposed. The two members are hooked together and covered with insitu concrete to complete the joint.

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14. 15 Waffle unit for flooring / roofing: - These are suitable for roofs / floors spanning in two directions. They are laid in a grid pattern. These units are cast in moulds . The saving achieved is not much. Also Shuttering are complicated and costly. Time consumption for construction is less

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16. 17 SLAB TO BEAM CONNECTION

17. Advantages Saving in cost, material, time & manpower. Shuttering and scaffolding is not necessary. Installation of building services and finishes can be done immediately. Independent of weather condition. Components produced at close supervision .so quality is good 18

18. Disadvantages Handling and transportation may cause breakages of members during the transit and extra provision is to be made . Difficulty in connecting precast units so as to produce same effect as monolithic. This leads to non-monolithic construction . They are to be exactly placed in position, otherwise the loads coming on them are likely to get changed and the member may be affected. 19

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