PREFABRICATED STRUCTURES

BY- S Yogesh 15MST1003VIT University, Chennai Campus

Prefabrication is the practice of assembling components of a structures 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.

Definition

Aim To effect economy in cost

To improve quality

To speed up construction since no curing is necessary

To use locally available materials

Advantages Work time is reduced

Less workers needed

Work done with better technology

Interruption in connection can be omitted

Limitations size of the units.

location of window openings has a limited variety.

site access and storage capacity.

require high quality control.

enable interaction between design phase and production planning.

difficult to handling & transporting.

Materials of Construction Materials like concrete, steel, hard wood,

aluminium etc…

Special characteristics while choosing materials

- Easy available

- Economy

- Easy workability

- Light weight

- Durability

MODULAR COORDINATIONModular coordination is a concept of coordination of dimension and space in which building components are positioned in terms of MODULE(M).

1M= 100mm

DIMENSIONS OF PRE FAB COMPONENTS

• Flooring and Roofing– Length- multiple of 3M– Width – multiple of 1 M– Thickness – multiple of M/4

• Beams– Length – multiple of 3M– Width – multiple of M/4– Depth – multiple of M/4

As per IS 15916(2011)

• Column– Height – multiple of 1M for height up to 2.8m and height above

28m is multiple of 2M– Lateral dimension- multiple of M/4

• Wall - Thickness – multiple of M/4

• Staircase– Width – multiple of 1M

• Lintels

– Length – multiple of 1M– Width – multiple of M/4– Depth – multiple of M/4

• Sunshade– Length – multiple of 1M– Projection- multiple of 1M

The following aspects of pre fabrication system:

a)Effective utilization of spaces

b) Straight and simple walling scheme

c) Limited sizes and numbers of components

d) Limited opening in bearing walls

e) Regulated locations of partitions;

f) Standardized service and stair units;

g) Limited sizes of doors and windows withregulated positions

ComparisonSite-cast

no transportation

the size limitation is depending on the elevation capacity only

lower quality because directly affected by weather

proper, large free space required

Precast at plant

transportation and elevation capacity limits the size-

higher, industrialized quality – less affected by weather

no space requirement on the site for fabrication

unlimited opportunities of architectural appearance

Hindustan Prefab limited.A Government of India Enterprise

ISO 9001: 2008 certified company was incorporated in 1953

HPL has built a wide spectrum of civil engineering structures using both conventional in-situ as well as prefab techniques and

supplied components for the building industry & the national railways

It also became the first company to produce precast pre stressed concrete railway bridge girders for making railway bridges in the country

HPL has a modern factory for manufacturing precast concrete products, which includes the following.

1) Precast pre stressed concrete products like Railway Sleepers and Electric Poles.

2) Autoclaved aerated cellular concrete. These are light weight yet have sufficient strength for walling and other applications.

3) Reinforced concrete products like pavements slabs, frames, water tanks, bridge girders, interlocking solid blocks for pavement & for retaining walls, kerb stone etc.

4) Timber joinery components and wood substitute items manufactured with wood/medium density fibreboard in the company’s timber workshop

HPL had designed and built many prestigious Institutional buildings. These comprise Schools, Colleges, Training Centres, Hospitals, Office Complexes and Airport Terminal Buildings.

The National Academy for Training and Research in Social Security (NATRSS) is a training centre with class rooms, auditorium, offices, lecture theatres, hostel block, health club, swimming pool and underground parking with a total covered area of 7200 sq. meters

The project cost was INR 62.4 Million.

Conclusiono Reduce adverse environmental impact on sites.

o Enhance quality control of concreting work.

o Reduce the amount of site labour.

o Increase worker safety .

o The use of precast concrete construction can significantly reduce the amount of construction waste generated on construction sites.