Under the Guidance of: Dr. Aswath M.U.

Presented by- Rahul Das Biswas

USN: 1BI14CSE14,

M.Tech (Structural Engineering)

Contents Introduction

Advantages

IS Recommendations

Materials

Prefabrication Systems

Types according to IS

Design Requirement as per IS

Progressive Collapse

Design of Ties

Design of Vertical Pillars (Walls, Diaphragms, Cores)

Frame installation

Conclusion

References

Introduction

WHAT ?

WHY ??

HOW ???

“What”

Precast:

Produced in Factories

Transported to Site

Assembled at Site

“Why”Advantages of Precast:

Partial or total saving of materials

Multiple using of shuttering

Better accuracy of workmanship

Less Man Power Required

Interruption in concreting can be omitted

“Why”

Advantages of Precast:

Fewer expansion joints

High capacity

Shorter construction time

Independent of adverse weather conditions

during construction

Continuing erection in winter time until -20 °C

“Why”

Advantages of Precast:

Opportunities for good architecture

Reduced energy consumption

Safety in construction

Low shrinkage with high strength

High modulus of elasticity

Very little micro cracks

“Why”

Advantages of Precast:

Resistance to chemical attack

Toughness and impact resistance

Volume stability

Durability against chloride attack

Reduced maintenance cost

Higher Strength at earlier ages and low heat of hydration

“How”

From Structural Engineering Point of view:

Material

Aspect

Type of Construction

Design (With all Safety Concern)

Detailing

IS CODES TO BE FOLLOWED

IS 15916: Precast Construction

IS 875: Design Loads

IS 456: Concrete

IS 1893 and IS 13920: Seismic Design

Characteristics of Material

Recommended by IS: 15916: 2011

• Easy Availability

• Light- Weight

• Thermal Insulation Property

• Easy Workability

• Durability

Characteristics of Material

Recommended by IS: 15916: 2011

• Non-combustibility

• Sound insulation

• Easy assembly and compatibility to form a complete

unit

• Economical

• Any other special requirement required for particular

application

Aspects to be considered as per the

Recommendation of IS: 15916: 2011

Effective utilization of spaces

Straight and simple walling scheme

Limited sizes and numbers of components

Limited opening in bearing walls

Aspects to be considered as per the

Recommendation of IS: 15916: 2011

Regulated locations of partitions

Standardized service and stair units

Limited sizes of doors and windows with

regulated positions

Structural clarity and efficiency

Aspects to be considered as per the

Recommendation of IS: 15916: 2011

Suitability for adoption in low rise and high rise

building

Ease of manufacturing, storing and transporting

Speed and ease of erection and

Simple jointing system

Types of Precast System according to

IS: 15916: 2011

Prefabrication System

Open Prefabrication

System

Partial Prefabrication

System

Full Prefabrication

System

Large Panel Prefabrication

System

Staircase Systems

Precast Floors Precast Walls

Box Type Construction

Design Requirement as per IS: 15916: 2011

Progressive Collapse

(A Major Threat to Safety of Structure)

Collapse or Failure of the major part

Due to the damage of small areas or

Failure of single element

Precaution: Against Progressive Collapse

1) All buildings should be capable of safely

resisting the minimum horizontal load of 1.5% of

characteristic dead load applied at each floor or

roof level simultaneously.

2) All Buildings Shall Be Provided With Effective

Horizontal Ties1) Around The Periphery

2) Internally (In Both Directions) &

3) To Columns & Walls.

3) All Buildings of Five or More Storeys Shall Be

Provided With Vertical Ties.

Precaution: Against Progressive Collapse

Design of Ties

(Peripheral Ties)At each floor and roof level an effectively continuous tie should be

provided within 1.2 m of the edge of the building or within theperimeter wall.

The tie should be capable to resisting a tensile force of Ft equal to 60 kNor (20 + 4N) kN whichever is less, where N is the number of storeys(including basement).

Design of Ties

(Internal Ties)

These are to be provided at each floor and roof level in two directions

approximately at right angles. Ties should be effectively continuous

throughout their length and be anchored to the peripheral tie at both

ends, unless continuing as horizontal ties to columns or walls.

Design of Ties

(Internal Ties)

• The tensile strength, in kN per meter width shall be

the greater of-

• gk + qk = Avg. characteristic D.L. + L.L in kN/m2

• lr = Greater of-• The distance between the centre of columns

• Frames or walls supporting any two adjacent floor spans in the

direction of the tie under consideration.

Design of Ties

(Internal Ties)

The bars providing these ties may be distributed evenly in the

slabs or may be grouped at or in the beams, walls or other

appropriate positions but at spacings generally not greater

than 1.5 lr.

Design of Ties

(Horizontal ties to column and wall)• All external load-bearing members such as columns and

walls should be anchored or tied horizontally into the structure at each floor and roof level. The design force for the tie is to be greater of-

a) 2 Ft kN or ls × Ft × 2.5 kN, whichever is less for a column or for each metre length if there is a wall. ls is the floor to ceiling height, in meter.

b) 3 percent of the total ultimate vertical load in the column or wall at that level.

• For corner columns, this tie force should be provided in each of two directions approximately at right angles.

Design of Ties

(Vertical ties)

Should be provided for buildings of five or morestoreys

Each column and each wall carrying vertical loadshould be tied continuously from the foundation to theroof level. The reinforcement provided is required onlyto resist a tensile force equal to the maximum designultimate load (dead and imposed) received from anyone storey.

In situation where provision of vertical ties cannot bedone, the element should be considered to be removedand the surrounding members designed to bridge thegap.

Design of Vertical Pillars

(Walls, Diaphragms, Cores)

Indian Standards for Designing Precast is

unavailable

Adopt any code of practice which is-

Safe

Durable

Economical

Reliable from Past Experience

Methods of mounting precast structures used in Russia will

be discussed

Primary Load-bearing Members of the Building

Optimal Configuration

The frame members to securely perform their

functions without “extra” efforts. This means that

the columns operate only for compression, floor

structures operate only for bending, with no

forces in the plane of the slab (the membrane

group of efforts), pylons take horizontal forces

ensuring the necessary rigidity of the building.

Optimal Configuration

• The principle of concentration of material isobserved. To reduce the material consumption theload should be transmitted through the minimumnumber of elements.

• The main feature of the framework is the abilityto ensure the integrated operation of all itselements: columns, pylons, floor slabs, foundationslab, piled and/or soil foundation. Proper use ofthese features can improve the designcharacteristics of the building frame whilereducing the consumption of its materials.

Rules of the Pylons Distribution

(Rule No. 1)

• All of the pylons should not be

intersected by straight lines on

which they are rested at one

point

• All of the pylons should not be

parallel

Building plan (slab & pylons)

Rules of the Pylons Distribution

(Rule No. 2)

The pylon should be sufficiently hard with a height of the

cross section equal to 1/10 – 1/5 of the building height.

With a smaller size the pylon will be more flexible and

will transmit a significant portion of the horizontal load

onto the columns or originate the need for more pylons.

If several flat diaphragms are connected to one core, the

height of their cross section can be reduced by virtue of a

more rigid joint operation with respect to the total

cumulative individual work.

It is necessary to strive for the minimum number of

pylons in the building.

Rules of the Pylons Distribution

(Rule No. 3)

Determining efforts in the plane of the slab

aab 5.26

Rules of the Pylons Distribution

(Rule No. 4)

If one looks at the aggregate of all the diaphragms of the

building combined with floor structures, it is possible to

find the shear center of the building. If the shear center

does not coincide with the center of gravity, the building

will have additional bending stresses. If the resultant

wind load does not pass through the shear center, the

building will be subject to additional twisting forces. The

configuration in which all three centers coincide will be

optimal. The easiest way to achieve is to prepare a

symmetrical in the two axes building plan with a

symmetrical arrangement of the pylons.

Frame installation

(Column)

Schemes Of Installation of Multi-story Columns Using A Set of Individual Installation

and Mounting Devices and Tooling a — the location of columns and accessories, b — securing columns by knees, c — clamp for

securing knees in the column; 1 — foundation socket, 2 — readymade mount, 3 — column, 4 —

clamp 5 — knee, 6 — drawbar of the knee, 7 — wedges, 8 — anchoring device, 9 — crimping

rope

Frame installation

(Cross beams)

Cross beam installation: a — applying an axial mark

on the column pillar; b — installing cross beam; c —

column pillar alignment

Frame installation

(Pylons)

Installation of interior walls — diaphragm plates — in a framed building: a —

installation, b — temporary fastening; 1 — knee-piece, 2 — diaphragm with a

cantilever replacing a collar beam, 3 — a universal sling, 4 — movable L-

clamp with a rack.

Frame installation

(Slab panels)

Laying bracing (spacing) (а) and lintel (b) floor slab panels

Conclusion

Considering its huge advantage, Technology

should be adopted in India

Safety should be the 1st concern

Past Hazards should be analyzed and

precautions to avoid it should be taken

Indian Standard Code required for Design

References

• http://en.wikipedia.org/wiki/Precast_concrete

• IS: 15916: 2011

• IS: 13920: 1993

• “DESIGN RULES FOR PRECAST CONCRETE:

VERTICAL PILLARS (WALLS, DIAPHRAGMS,

CORES)” By- Mark P. Son & Denis V. Konin, Redecon

2014, Bangalore

• “Design and Construction of Multi-Storey Residential

Buildings with Precast Concrete” By- Dr. H S Lai ,

Redecon 2014, Bangalore