What is Scaffolding ? and types of scaffolding.
A temporary structure use in building operations to support platforms for workmen, structural materials essential require during construction at raise heights ( > 1.5 m ) is refer as scaffolding.
It is very useful in construction, demolition, repair and maintenance works carry on various civil engineering structures such as buildings, bridges, dams, tanks etc. This type of arrangement is provide either on one or both the sides of the walls. In case of ordinary works. These may be erect on one side only but must be provide on both sides if work is of superior quality. The height should be adjust with the progress of the work.
This is also refer as single scaffolding. This type of scaffolding consists of bamboos and poles except platforms. In this case, single row of standards ( i.e. vertical members ) are driven into the ground. The distance between two standards varies from 1.5 m to 2.0 m. The standards are driven about 1.2 m to 1.5 m away from the main face of the wall. Standards may be place in tubs or barrels fill with sand or earth in case these can not be driven into the ground. Sand or earth is fill in order to make the standard strong against any movement or slipping.
The standards are, then, connect to each other by longitudinal horizontal members ( i.e. ledgers ) at every vertical rise of 1.2 to 1.5 m. They are provide on the building side and are secure by rope lashings. After this, the put logs ( i.e., transverse horizontal members ) are place at a horizontal distance of 1.2 m to 1.5 m such that on one side they are support on ledgers and on the other are held in the holes provide in the wall. They are fix to ledgers by rope lashings.
After this, cross braces and guards boards etc. are fix for increasing the strength and to guard against materials at working level respectively.
The platform is raise higher and higher during the progress of the work, if need be. When the work is complete, the arrangement is remove and the holes are fill with soil as soon as the standards are remove.
This is also refer as double scaffolding. It is stronger than brick layer’s scaffolding. This type of scaffolding is mainly use for stone masonry, superior brick work and surface finishing of costly structures. The arrangement is similar to the brick layer’s scaffolding. The only difference is that in this case two rows of standards are use.
The standards in the first row are driven at a distance of 15 cm from the face of the wall whereas those of second row are driven at a distance of 1.2 to 1.5 m away from the wall face. The put logs are support at the ends on both the ledgers. In this case, holes are not provide in the wall to support the putlogs. In some of the cases, instead of diagonal braces, indicate supports ( i.e., raking shore or shoring ) are provide to increase the resistance of the scaffold from slipping away from the wall face.
This type of scaffolding is also refer as steel scaffolding. In this case, wooden members are replace by steel tubes and rope lashings are substitute by special coupling at junctions and joints.
The diameter of the steel tube varies from 4 cm to 6.5 cm and its thickness is about 5 mm. The standards are space at a distance of about 3 m. Each one is weld to a base plate which may be circular or square in plan. The plate has holes so that it can be spike to a concrete or timber base in order to form a rigid foundation for scaffolding. Ledgers are space at 1.8 m vertically apart. The length of putlogs i.e., short steel tubes varies from 1.2 to 1.8 m in length. No holes are require in the wall for bearing the putlogs because these have special end of fit into the joints in the wall face.
This type of scaffolding has several advantages and therefore is generally prefer over other ordinary timber scaffolding. The advantages are :
- Suitable for any height.
- Economical in long run inspite of its higher initial cost.
- It can be rapidly erect and dismantle.
- It is durable.
- Strong as compare to other types.
- Possesses fire resisting qualities.
- Use for painting the walls and underside of roofs etc. if it is mount on bogie wheels.
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