Ct Report

PRECAST CONCRETE

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

INDEX S.N O. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

CONTENTS INTRODUCTION PROCESS OF CONSTRUCTION PRECAST PRECAST STRUCTURAL SYSTEM ILLUSTRATIONS-FRAME SYSTEM PRECAST LOAD BEARING WALL PRECAST STRUCTURAL ELEMENTS STRUCTURAL CONCEPT ILLUSTRATIONS ADVANTAGES AND BENEFITS PRODUCTS AND SERVICES EXAMPLES OF PRECAST BUILDINGS IN INDIA BIBLIOGRPHY

PAGE NO. 1 2 3 4-7 8-9 10-13 14-16 17 18-19 20 21. 22.

The concept of precast (also known as “prefabricated”) construction includes those buildings, where the majority of structural components are standardized and produced in plants in a location away from the building, and then transported to the site for assembly. These components are manufactured by industrial methods based on mass production in order to build a large number of buildings in a short time at low cost. PRECAST COMPONENTS ARE MADE IN A FACTORY AND The division and specialization of the human workforce DELIVERED TO No space needed on site for storing moulds an reinforcement. SITE WHERE  The use of tools, machinery, and other equipment, usually automated, in the THEY ARE LIFTED STRAIGHT FROM production of standard, interchangeable parts and products UNLOADING STRAIGHT ONTO BUILDING THE LORRY ONTO Compared to site-cast concrete, precast concrete erection is faster and less THE BUILDING.

The main features of this construction process are as follows:

affected by adverse weather conditions.  Plant casting allows increased efficiency, high quality control and greater control on finishes. BETTER FINISHES CAN BE OBTAINED WITH PRECAST CONCRET E BECAUSE THE INSIDE SURFACE OF THE MOULD IS KEPT IN GOOD CONDITION.

INTRODUCTION

MOVING INTO POSITION

FINAL PLACING

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

1.

3. MIX BEING POURED: Carefully specified concrete is placed into the mould. Many precast works now employ computer controlled batching plants.

1. PRODUCTION OF REINFORCED CAGES AND MAIN CONNECTIONS: The precast factory often has specialist workshops for the manufacture and maintenance of moulds, and for the production of jig-built reinforcing cages and connections.

6. STORAGE OF HIGH-QUALITY UNITS IN WORKS AREA: The finished precast components are stacked on clean battens or plastic pads positioned to suit the design of the component. Care is taken to keep the stacks vertical and to ensure that battens are placed directly above one another within the stack.

2. ASSEMBLY OF MOULDS: The reinforced cage is positioned in the partly assembled mould, then the remaining mould section is completed.

5. PRECAST CONCRETE BEING MOVED TO THE STORAGE AREA: Once an appropriate strength has been reached, the precast units are moved to the storage area. Units are usually handled within hours of casting as part of the rapid production cycle.

4. COMPACTION OF CONCRETE USING POKER VIBRATOR: To ensure that optimum density is obtained and that specified strengths are achieved, concrete is placed and compacted using high-frequency external vibrators or pokers.

7. TRANSPORT TO SITE:

PRECAST CONCRETE PROCESS

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

2.

•Depending on the load bearing structures, the most common precast structural systems areSTRUCTURAL SYSTEMS

FRAME SYSTEMS

LOAD BEARING WALLS AND FLOORS

CELL SYSTEMS

1.FRAME SYSTEMS •Frame structures are suitable for buildings which need a high degree of flexibility. Large spans and open spaces can be achieved without interfering walls. •This system is particularly suitable for shopping malls, multistory car parks, sports facilities, office buildings and industrial buildings.

2. LOAD BEARING WALLS AND FLOORS • Precast load bearing walls can appear as walls in shafts and cores, cross-walls and load bearing external walls. •Precast wall systems have been used in residential projects. they provide advantages of fast construction ,ready to paint surface finish, acoustic insulation and fire resistance. • The slabs between walls can either be precast or in-situ flat plate structure. •The aim is to build free open spaces between the load bearing walls and to use partition walls for the internal layout.

3. CELL SYSTEMS •Cell units are feasible for specific uses of a building, for instance, bathrooms and kitchens. •The advantage of the system lies in the speed of construction and high productivity in manufacturing since finishing's and fittings of the cells are completely done at the factory.

PRECAST BUILDING SYSTEM

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

3.

BEAM TO COLUMN CONNECTION DETAIL

Structurally continuous beam–column connection may be created by passing a tendon from a pocket in the top of one beam, through the column, to a pocket in the top of the other beam. The tendon is anchored to a plate in one pocket as it is tensioned by a jack in the other pocket.

ILLUSTRATIONS-FRAME SYSTEM

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

4.

A

DETAIL AT A. (SECTIONAL VIEW)

Topped hollow-core roof slabs supported on beams are joined to a column with vertical rods. A similar connection can be used for floor beams resting on corbels.

ILLUSTRATION 2

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

5.

(c) Short pieces of steel angle are welded to the plates to join the beams to the columns. Smooth-top hollowcore precast concrete planks are placed on bearing pads on top of each beam. Grout is poured into the gap between the ends of the planks to unite loops of reinforcing that project from the tops of the beams, reinforcing bars that are inserted through the loops, and lateral pieces of reinforcing bar that are grouted into the keys between planks. The end result is a tightly connected assembly that supports an untopped precast concrete floor or roof.

The beams in this system of framing rest on concrete corbels that are integrally cast with the column. The smooth-topped hollowcore slabs are detailed for use without topping. (a) Weld plates are cast into the column. (b) Beams are placed on bearing pads on the corbels. There is a weld plate cast into the top of each beam at the end.

ILLUSTRATION 3

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

6.

•This column-to-column connection uses proprietary sleeves that are cast into the lower end of the upper column section. •Before the sections are assembled (upper left), the lower ends of the vertical bars from the upper column section, which reach down to the midheight of each sleeve, are the only contents of the sleeves. •Assembly of the column sections starts with the placement of a stack of steel shims in the center of the top of the lower section. •These shims serve to adjust the height of the column and to maintain a space for grouting between the two sections.

ILLUSTRATION 4

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

7.

•Precast concrete walls provide an excellent envelope for low rise commercial and industrial buildings. They are relatively easy to manufacture, structurally efficient and durable. •Precast walls have been used for seismic load resistance by designing them to emulate cast-in place shear walls. •This is typically accomplished using ductile vertical reinforcing coupled with splice sleeves to create continuity across horizontal wall joints. •In adopting the wall thickness, structural adequacy is not the sole consideration. Other factors to be considered include: • Connection details for supported beams and slabs. • Sound transmission and fire rating. • Joint details at panel-to-panel connections. • Possible future embedded services, which could reduce the concrete area • available. •Based on typical layouts and building configurations, a thickness of 180mm is recommended for the precast panels.

PRECAST LOAD BEARING WALL

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

8.

PRECAST NON-LOAD BEARING FACADE PANELS Typically, the wall panels for the front and rear elevations are non-load bearing facade elements. Support of these panels is achieved by any of the following methods: • The facade panel is connected to main load bearing walls and is designed to carry its own weight between supports. • The facade panel is connected to the floor slab or beam, which is then designed to provide support to the wall.

These panels will typically be designed for vertical loads due to self weight and an allowance for floor loads, if applicable, in addition to horizontal loads due to external wind pressures. A typical panel thickness of 120mm is proposed on the basis of strength considerations and to accommodate window fixings and profiles around the window perimeter.

PRECAST NON LOAD BEARING WALL

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

9.

PRECAST CONCRETE SLABS

•The most fully standardized precast concrete elements are those used for making floor and roof slabs. •These may be supported by bearing walls of precast concrete or masonry or by frames of steel, site cast concrete, or precast concrete.

TYPES OF PRECAST SLAB ELEMENTS

FOR SHORT SPANS AND MINIMUM SLAB DEPTHS, SOLID SLABS ARE APPROPRIATE.

PRECAST STRUCTURAL ELEMENTS

ESTIMATE SIZE

PRECAST SOLID SLAB

DEPTH-90mm to 200mm

PRECAST HOLLOW-CORE SLAB

DEPTH SPAN 200mm 7.6m 250mm 9.8m 300mm 12m

PRECAST CONCRETE DOUBLE TEES

COMMON DEPTHS300.350,400,460mm

PRECAST CONCRETE SINGLE TEE

DEPTH-915mm SPAN-2.5m

PRECAST CONCRETE COLUMN

250mm,300mm,,40 0mm,600mm

IN HOLLOW-CORE SLABS, PRECAST ELEMENTS SUITABLE FOR INTERMEDIATE SPANS, INTERNAL LONGITUDINAL VOIDS REPLACE MUCH OF THE NONWORKING CONCRETE.

FOR THE LONGEST SPANS, STILL DEEPER ELEMENTS ARE REQUIRED, AND DOUBLE TEES AND SINGLE TEES ELIMINATE STILL MORE NONWORKING CONCRETE.

STANDARD PRECAST CONCRETE BEAM AND GIRDER SHAPES.

PRECAST STRUCTURAL ELEMENTS

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

10.

1. PRECAST REINFORCED CONCRETE FLOOR SYSTEMS: .The precast reinforced concrete floor beams, planks, tee beams or beam and infill blocks that require little or no temporary support and on which a screed or structural concrete topping is spread are commonly used with structural steel frames and may be used for in situ cast floors. .Precast beams and plank floors that require no temporary support in the for of centering are sometimes referred to as self-centering floor. .The advantage of these precast floor systems is that there is a saving in site labor.

PRECAST CONCRETE PLANK FLOOR UNIT:  These comparatively thin, prestressed solid plank, concrete floor units are designed as permanent shuttering and for composite action with structural reinforced concrete topping. The units are 400 or 1200 wide,65,75 or 100 thick and up to 9 and half meters long for floors and 10 meters long for roofs.

The two most common types are:

PRECAST PRECAST HOLLOW HOLLOW FLOOR FLOOR UNITS: UNITS:  Theses precast hollow floor units  Theses precast hollow floor units are are generally 400-12200 400-12200 generally wide,110,150,200,250 or or 300 300 thick thick and and wide,110,150,200,250 up up to to 10 10 meters meters long long for for floors floors and and thirteen and a half meter long for thirteen and a half meter long for roofs. roofs. The purpose of voids or hollows in The purpose of voids or hollows in the the floor unit unit is is to to reduce reduce dead dead weight weight floor without affecting affecting strength. strength. The The without reinforcement reinforcement is is cast cast into into webs webs between between hollows. hollows.

PRECAST STRUCTURAL ELEMENTS

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

11.

PRECAST BEAM AND FILLER BLOCK FLOOR:

•This floor system consists of precast reinforced concrete planks or beams that support precast hollow concrete filler blocks. •The planks or beams are laid between them and a concrete topping is spread over the planks and filler blocks. •The reinforcement protruding from the top of the plank acts with the concrete topping to form reinforced concrete beam. •The advantage of this system is that the lightweight planks or beams and filler blocks can be lifted much more easily and placed in position than the much larger hollow concrete floor units.

HOLLOW CLAY AND CONCRETE FLOOR:

1. A floor system of hollow clay blocks and in situ cast reinforced concrete beams between the blocks and concrete topping cast on centering and falsework, resisting properties of the blocks. This floor system is much less used because of the very considerable labor in laying the floor.

PRECAST CONCRETE TEE BEAMS: Precast prestressed concrete tee beam floors are mostly used for long span floors in such buildings as stores, supermarkets, swimming pools and multi-storey car parks where there is a need for wide span floors and the depth of this type of floor is not a disadvantage. The floor units are cast in the form a double tee.

PRECAST STRUCTURAL ELEMENTS

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

12.

FOOTING BELOW PRECAST LOAD BEARING WALLS

PRECAST WALLS

•The foundation loads for the precast structural system will be similar to those for conventional design. •The arrangement of the foundations below the load bearing walls will be different to those normally adopted for a column and beam structural system. •The desirable arrangement should provide a relatively uniform support along the length of the wall and minimize the eccentricity effects due to any possible misalignment of the walls relative to the foundations.  In the case of a footing foundation system, the recommended solution is a continuous strip footing below the load bearing walls, as shown in Figure.

GROUT

GROUND BEAM AND SLAB

FOOTING

Similarly, a raft foundation system, as shown in Figure I. will provide a uniform support to the load bearing walls and excellent resistance to eccentricity effects.

I. PRECAST LOAD BEARING WALL ON STRIP FOOTING OR RAFT FOUNDATION

II. PRECAST LOAD BEARING WALL ON PILED FOUNDATION

For a piled foundation, uniform support along the full length of the wall can be provided by adopting piles at closer spacing with a first storey capping beam. This solution is unlikely to be economical. The recommended approach is shown in Figure II. which is based on the following structural concept: • Within the precast concrete wall, zones are designated as load bearing and no-load bearing. • Piles are located below the load bearing zones only. • The piles are preferably provided in groups of two or more, located on each side of the wall centerline. If single piles are necessary, first storey beams are required in the transverse direction to accommodate any possible eccentricity effects.

PRECAST FOUNDATION

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

13.

Based on considerations of buildability, economy and standardization of precast components, the structural concept developed consists of: • Conventional foundations comprising footings, raft slab or piles and pile caps. • Cast in-situ first storey, typically reinforced concrete beam and slab system. • Precast concrete load bearing walls. • Precast concrete non-load bearing façade panels. • Precast concrete floor system, either: - Precast concrete beams and precast slabs (reinforced concrete or prestressed) with a composite in-situ topping or Precast concrete walls with precast concrete slab system

PRECAST PRESTRESSED SLABS SPANNING BETWEEN WALLS WITH COMPOSITE IN-SITU TOPPING FOR 1ST STOREY

STRUCTURAL CONCEPT

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

14.

PRECAST PRESTRESSED SLABS SPANNING BETWEEN WALLS WITH COMPOSITE IN-SITU TOPPING FOR 2ND STOREY

PRECAST PRESTRESSED SLABS SPANNING BETWEEN WALLS WITH COMPOSITE IN-SITU TOPPING FOR ROOF

STRUCTURAL CONCEPT

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

15.

WORKERS GUIDE TWO HOLLOW-CORE SLABS, LOWERED BY A CRANE IN WIRE ROPE SLINGS, ONTO THE PRECAST CONCRETE BEAMS THAT WILL SUPPORT THEM.

A FULLY PRECAST BUILDING FRAME UNDER CONSTRUCTION. A POURED CONCRETE TOPPING WILL COVER THE HOLLOW-CORE SLABS AND THE BEAMS TO CREATE A SMOOTH FL OOR AND TIE THE PRECAST ELEMENTS TOGETHER.

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

16.

DOUBLE-TEE SLAB ELEMENTS SUPPORTED ON A FRAME OF PRECAST COLUMNS AND L-SHAPED GIRDERS

DOUBLE-TEE SLAB ELEMENTS SUPPORTED ON A PERIMETER OF PRECAST CONCRETE LOADBEARING WALL PANELS AND AN INTERIOR STRUCTURE OF PRECAST COLUMNS AND INVERTED TEE BEAMS.

HOLLOW-CORE SLAB ELEMENTS SUPPORTED ON PRECAST CONCRETE LOADBEARING WALL PANELS.

ILLUSTRATIONS

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

17.

FLEXIBILITY OF SHAPE AND FORM: Concrete can be molded into any shape, hence it is used to provide custom made design solutions.

STRENGTH: precast exterior cladding can be easily designed to handle structural building loads.

DURABILITY: Studies have shown that concrete products can provide a service life in excess of 100 years.

BENEFITS AND ADVANTAGES

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

18.

DESIGN-BUILD EFFICIENCY: Precast

concrete provides an efficient delivery model for your project; allowing building construction to proceed while the design is developed. ESTHETICS: An unlimited array of colorings, textures and patterns can be added to the concrete mix, or textured paints of any color may be used, for exceptional effects.

ENERGY EFFICIENCY: The thermal mass inherent to precast concrete lends itself to energy efficiency and reduces the heating and cooling peaks and loads; often necessitating less costly mechanical systems. ENVIRONMENTALLY FRIENDLY: An inherent characteristic of precast concrete is its natural resistance to mold, greatly reducing health concerns from VOCs and off gassing. With these environmentally friendly advantages, precast concrete satisfies a growing demand for sustainable design and construction. Additionally, precast concrete structures are completely recyclable making their impact on the environment minimal. BENEFITS AND ADVANTAGES

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

19.

AGRICULTURAL PRODUCTS

CEMENTERY PRODUCTS

UTILITY STRUCTURES

PRODUCTS INCLUDE: BUNKER SILOS ,CATTLE FEED BUNKS,CATTLE GAURDS ETC

PRODUCTS AND SERVICES

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

20.

SANTUSHTI HOMES AT BHIWADI 250 affordable homes G+3 Storied 3 Blocks Load bearing Precast walls Precast Solid Slabs (room size) Site Based Precast Plant Design Approved by IIT Delhi

“COMMUNE-1” AT BANGALORE

“LAKESIDE” AT CHENNAI

550 apartment scheme Basement +G+13 Load bearing Precast walls Precast Solid slabs Site based Precast Plant

300 apartment scheme Stilt + 4 Storied 6 Blocks Load bearing Precast walls Precast Hollow-core slabs Dedicated Precast Plant Design Approved by IIT Delhi

“MARVEL SANGRIA” AT PUNE Commercial Building of 250,000 sqft Shops at Ground & Mezzanine floor B+G+3 Storied 3 Blocks Load bearing Precast walls Precast hollow-core slabs Precast Portal Frames at all floors Precast Retaining Walls at Basement Precast Plant located at Pune

EXAMPLES OF SOME PRECAST BUILDINGS IN INDIA

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

21.

•ebooks.narotama.ac.id •McKay •www.bca.gov.sg •www.fpcaweb.org •www.researchgate.net •precast.org

ARUSHI BANDHU SECOND YEAR A ROLL NO. 5

22.