OPEN PREFAB CONSTRUCTION SYSTEM

SUBMITTED BY : ANUJ SINGHAL GITANSHU AVNISH HARSHIT PANT DIVYANSH HIMANSHU CH.

What Is Prefabrication?

Prefabrication is the practice of 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.

AIMS OF PREFABRICATION1. To speed up the construction time.

2. To lower the labour cost .

3. To ensure precise conformity to building codes , standards and greater quality assurance.

4. To allow less wastage of materials than in site- built construction.

5. To ensure higher worker safety and comfort level than in site- built construction

THE LIMITATIONS  OF PREFABRICATION ARE: 1.A small number of units required may prove to be uneconomical

2. Special connections, such as special bearings to transmit the vertical and horizontal loads, can add cost to the system

3. Waterproofing at joints

4. Transportation difficulties

5. Need for cranes

ADVANTAGES OF PREFABRICATION

High quality product Labour related savings Savings in time Overall efficiency is greatly increased Mass production is easier and quick Protected and controlled production in

environment Potential for lower production costs and other

cost savings Independent climate conditions The disruption of traffic is avoided Ensures high degree of safety

CHARACTERISTICS ARE TO BE CONSIDERED Easy availability Light weight for easy handling and

transport, and to economieson sections and sizes of foundations;

Thermal insulation property; Easy workability; Durability in all weather workability; Durability in all weather conditions; Non combustibility Economy in cost, and Sound insulation

DISADVANTAGES

Carefull handling of prefabricated components such as concrete panels or steel and glass panels os required.

Attention has to be paid to the strength and corrosion- resistance of the joining of the prefabricated sections to be avoid failure of the joint

Similarly, leaks can form at joints in prefabricated components.

Transportation costs may be higher for voluminous prefabricated sections then for the materials of which they are made, which can often be packed more compactly.

Large prefabricated sections required heavy-duty cranes and precision measurement and handling to placing position.

MATERIALS TO BE USED IN PREFABRICATED SYSTEM

• Concrete• Steel• Treated wood• Aluminium • Cellular concrete• Light weight concrete

elements• Ceremic products etc

COMPONENTS OF PREFAB CONSTRUCTIONFlooring and roofing schemes Beams ColumnsWallsStaircaseLintelsSunshade/chajja projection

VARIOUS PREFABRICATED CONSTRUCTION SYSTEMSIn conceptual dimension, prefabrication can be categorized as:

1.OPEN PREFAB SYSTEM: This system is based on the use of the basic structural elements to form whole or part of a building. The standard prefab concrete components which can be used are:1. Reinforced concrete channel units.2. Hollow core slabs3. Hollow blocks and battens4. Precast planks and battens5. Precast joist and tiles6. Cellular concrete slabs7. Prestressed/ Reinforced concrete slabs8. Reinforced / Prestressed concrete beams9. Reinforced / Prestressed concrete columns10. Precast lintels and chajjas11. Reinforced concrete waffle slabs/ shells12. Room size reinforced/ prestressed concrete panels13. Reinforced / Prestressed concrete walling elements14. Reinforced / Prestressed concrete trusses

CATEGORIES OF OPEN PREFEB SYSTEMS

There are two categories of open prefab systems depending on the extent of prefabrication used in the construction as given below:

1. Partial prefab open system 2. Full prefab open system

Partial prefab open system: This system basically emphasizes the use of precast roofing and flooring components and other minor elements like lintels, chajjas, kitchen sills in conventional building construction. The structural system could be in the form of in-situ framework or load bearing walls.

Full prefab open system: In this system almost all the structural components are prefabricated. The filler walls may be of bricks or any other local material.

PREFABRICATED HOUSING

Bridgetown, Barbados

EXAMPLES OF BUILDINGS WITH PREFABRICATED CONSTRUCTION SYSTEM

McDonalds, UKT30A Hotel Tower, China

NAKAGIN CAPSULE TOWER

LOCATION: TOKYO, JAPAN

BUILDING STATISTICS-• SITE AREA: 442 SQUARE METRES BUILDINGAREA: 430 SQUARE METRES TOTAL FLOORAREA: 3,091 SQUARE METRES.

• STRUCTURE DETAILS: STRUCTURAL STEELFRAME PARTLY ENCASED IN CONCRETE MAXOF 140 CAPSULE UNITS (PREFABRICATED) 11-13 STORIES INCLUDING 1 BASEMENT

• MATERIAL DETAILS: CAPSULE EXTERIOR:STEEL WITH SPRAYED PAINT FINISH CAPSULE INTERIOR: STEEL CAPSULE WITH CLOTHCEILING AND FLOOR CARPETTOWERS:CORTEN STRUCTURAL STEEL FRAME LOWERLEVELS: FAIR-FACED REINFORCED CONCRETE

• Methodology: Japanese Metabolism,physical objects are never eternal,celebrates individualism, response tolong commutes.

• Units of Prefabrication: Capsulesarrive from factory completelyprefabricated, ready to be lifted bycrane and bolted onto thesuperstructure.

• Structure: Steel frame with lightweightconcrete shaft which housesvertical circulation, mechanical shafts.

• Delivery: Dense urban surroundingsmeant that capsules were deliveredfrom factory to site on the same day itwas attached to the superstructure

THE CAPSULE :THE STEEL FRAME CAPSULES (WHICHHAVE BEEN DESIGNED TO BEREPLACEABLE, REMOVABLE, ANDTRANSPORTABLE) WERE PREFABRICATEDIN SPECIALIST FACTORIES ANDASSEMBLED AT A PLANT BEFORE BEINGDELIVERED TO THE SITE. EACH ONE WASLIFTED BY MECHANICAL CRANES ANDWERE ATTACHED TO THE TOWER SHAFTSUSING 4 HIGH-TENSION BOLTSTHE CAPSULE INTERIOR WAS PREASSEMBLEDIN A FACTORY THEN HOISTEDBY CRANE AND FASTENED TO THECONCRETE CORE SHAFT.

DETAIL OF SYSTEM OF CAPSULE JOINING TO SHAFT

Capsule Delivery1. Capsule Base Connections Détail2. Capsule Bolting Process3. Capsule Bolting Connection Detail4. Prefabrication - 3 Hour Assembly5. Transportation - 500km6. Construction - 7-8 Months