Innovative structural slab practices - Voided Slabs

Content Introduction

Experimental Study

Advantages

Materials

Scope of Future

Conclusion

Background

Compression zone

Tensile zone

Inactive concrete

Central portion of RCC solid slab(simply supported)

Problems with inactive concrete:

additional weight span limitations material wastage energy consumption

Solution ?

History• The first hollow concrete block was designed in 1890 by Harmon S. Palmer in

United States.

• In 1900 Palmer got patent for his design of hollow concrete blocks.

• By 1905 it is estimated that 1500 companies start manufacturing hollow concrete blocks.

• In 1950’s first , hollow-core slab was invented.

How ?

Hollow Core Slabs

Problem :Strength in one direction onlyInflexibility Reduced architectural possibilitiesLack of structural integrity

Pre fabricated one way spanning concrete elements with hollow cylinders, replacing inactive concrete

Solution ?

Voided Slabs/ Bubble Deck Slab

The best solution for above two problems is Bubble Deck Slab.

Bubble Deck Slab is a Biaxial voided concrete slab in which high density polythene hollow spheres replace the ineffective concrete in the centre of concrete slab.

Why Bubble Deck Slab ?

Flat slab technology (no need of beams )

Longer spans

Pre fabricated&

cast in-situ

No compromise for strength& serviceability

-: Theory :-

Voided slab also distribute load same as simple slab, and the best part design is also same as of simple slabs.

Analysis Of Voided Slabs

Voided slabs are like combinations of small I-section beams but behaves same as simple slab.Since maximum shear force in slab is near to column, so that portion is constructed as an RCC, no fillers are used.

Advantages Of Voided Slabs

It eliminates dropdown panels and extra sporting beams. Light in weight which makes foundation also less deep.Because of light weight no need of column in less spacing.

Some More Advantages Of Voided Slabs

EnvironmentLess material and energy consumptionReducing CO2 emission up to 40 kg/m2 1kg of plastic replaces 100kg of concreteEvery component can be recycled

EconomySavings in materials Transportation costs reducedFaster construction timeBuildings can be more flexible and easy in

installations

Experimental Studies

1.Shear strength- 80% of solid deck slab

2.Deflections - same as solid deck

3.Weight - 40% less than a solid slab

4.Fire resistance - 65% of solid slab

MILLENNIUM TOWER (ROTTERDAM)

First high rise building erected with Bubble Deck

Height of the building is 131 m

Second Highest building in Netherlands 34 stories were constructed

Components

Lattice Girder o Grade Of Steel : Fe 415, 500

o Spacing : Max. 1m or maximum 3 ball between two girder

o Main bar 10 mm minimum – for 200 to 300 mm slab thickness

o Main bar 12 mm ≥300 mm

Filler Material • Mangalore tiles

• Burnt Clay Bricks

• Hollow Concrete blocks

• Stabilized Mud blocks

• Hollow Mud blocks

• Clay pots

• Coconut shells

• Plastic ball or cuboids

Concrete • Type : Self compacted concrete

• Grade can be as per design

Scope of Future Use

Used for constructing all types of building especially sky scrapers

Best for larger span halls like theatres and auditoriums

Pedestrian bridge decks

Used in parking areas as less number of columns are required

Conclusion

Obviously this intellectual slab design may become the future of slab construction which gives a tremendous contribution in Sustainable development.

Thank You