slabs by rhythm murgai

L -3 T -0 P-0COURSE TITLE: STRUCTURE SYSTEMS AND DESIGN

COURSE CODE: ARC054

WEEK NO.: 4 LECTURE NO.: 13

LECTURE DETAIL : BULK ACTIVE STRUCTURES –SLABS

COURSE INSTRUCTOR: AR. SHIVALIKA KANWAR UID: 19514

CA CATEGORY: ______________

EXAM CATEGORY: 55: Mid Term Exam: All Subjective

LSAD : AD01 : ARCHITECTURE

2LECTURE NO.10

CONTENT TOPIC: BULK ACTIVE STRUCTURES


ELEMENTS OF BULK ACTIVE STRUCTURES

COLUMNS BEAMS SLABS

3LECTURE NO.10

CONTENT TOPIC: BULK ACTIVE STRUCTURES- SLABS


R.C.C. SLABSReinforced Cement Concrete Slab•A Reinforced Concrete Slab is the one of the most important component in abuilding. It is a structural element of modern buildings. Slabs are supported onColumns and Beams.•RCC Slabs whose thickness ranges from 10 to 50 centimetres are most oftenused for the construction of floors and ceilings.•Thin concrete slabs are also used for exterior paving purpose.

http://www.civilprojectsonline.com/building-construction/guide-to-design-of-rcc-columns/

http://www.civilprojectsonline.com/building-construction/guide-to-doubly-reinforced-rcc-beam-design/

4LECTURE NO.10



R.C.C. SLABS

5LECTURE NO.10



R.C.C. SLABS

Reinforcement design-

•One way slab hasstructural strength inshortest direction.•Two way slab hasstructural strength intwo directions.•Flat plate slab•Flat slab•Grid slab

On

the

bas

iso

fre

info

rce

me

nt

Various types of slabs

6LECTURE NO.10



R.C.C. SLABSO

nth

eb

asis

of

rein

forc

em

en

t

Reinforcement design-

•One way slab hasstructural strength inshortest direction.•Two way slab hasstructural strength intwo directions.•Flat plate slab•Flat slab•Grid slab


7LECTURE NO.10



R.C.C. SLABS- two way slab

8LECTURE NO.10



R.C.C. SLABS- flat plate slab

9LECTURE NO.10



R.C.C. SLABS – flat slab

10LECTURE NO.10



R.C.C. SLABSO

nth

eb

asis

of

typ

eo

fco

nst

ruct

ion

•Prefabricated concrete slabs are cast in a factory and then transported to the siteready to be lowered into place between steel or concrete beams.•They may be pre-stressed (in the factory), post-stressed (on site), or unstressed.Care should be taken to see that the supporting structure is built to the correctdimensions to avoid trouble with the fitting of slabs over the supporting structure.•In situ concrete slabs are built on the building site using formwork. Formwork is abox-like setup in which concrete is poured for the construction of slabs.•For reinforced concrete slabs, reinforcing steel bars are placed within theformwork and then the concrete is poured.•Plastic tipped metal, or plastic bar chairs are used to hold the reinforcing steelbars away from the bottom and sides of the form-work, so that when the concretesets it completely envelops the reinforcement.•Formwork differs with the kind of slab. For a ground slab, the form-work mayconsist only of sidewalls pushed into the ground whereas for a suspended slab, theform-work is shaped like a tray, often supported by a temporary scaffold until theconcrete sets.

A concrete slab can be cast in two ways: It could either be prefabricated or cast insitu.

LECTURE NO.10



R.C.C. SLABSO

nth

eb

asis

of

sup

po

rt

These slabs could be cantilevered or Simply Supported Slabs.

cantilevered


12LECTURE NO.10



R.C.C. SLABSFor a suspended slab, there are a number of designsto improve the strength-to-weight ratio. In all casesthe top surface remains flat, and the underside ismodulated:

•Corrugated, usually where the concrete is pouredinto a corrugated steel tray. This improves strengthand prevents the slab bending under its own weight.The corrugations run across the short dimension,from side to side.•A filler slab, is normal RCC slabs where bottom half(tension) concrete portions is replaced by fillermaterials.•A ribbed slab, giving considerable extra strength onone direction.•A waffle slab, giving added strength in bothdirections.

On

the

bas

iso

fP

RO

FILE


13LECTURE NO.10



CORRUGATED SLAB• Corrugated sheet steel profile (support sheet), the

indentations of which allow it to provide support to theconcrete.

• Anti-fracture mesh, which is positioned in a similarmanner to when employed for solid slabs and theobjective of which is the prevention of fracturesprovoked by retraction and temperature.

• Negative Framework, which is installed in the uppersection of the slab and centred in the indentations. Itspurpose it to absorb the tensile stresses generated inthe adjacent slabs’ supports.

• Fire-resistance framework, which installed in the sameway as the negative framework but in the lower sideof the indentations. This is a positive framework that isinstalled to ensure that the slab’s fire-resistancecomplies with the project’s specifications.

• Concrete, which is poured directly onto the compositeslab.

On

the

bas

iso

fP

RO

FILE

14LECTURE NO.10



FILLER SLABO

nth

eb

asis

of

PR

OFI

LE

• Filler slabs are normal RCC slabs where bottomhalf (tension) concrete portions are replaced byfiller materials such as bricks, tiles, cellularconcrete blocks, etc. these filler materials are soplaced as not to compromise structural strength,result in replacing unwanted and non functionaltension concrete, thus resulting in economy. Theseare safe, sound and provide aesthetically pleasingpatterns ceiling and also need no plaster.Light weight, inert and inexpensive materials such as

low gradeMangalore tiles, Burnt Clay Bricks, Hollow

Concrete blocks, Stabilized Mud blocks/ Hollow Mud

blocks, Clay pots, Coconut shells etc. can be used as

filler materials. These materials are laid in the grids of

steel reinforcement rods and concreting/concrete topping is done over them.

http://sepindia.org/ihd-sep/ceeef-technologies/filler-slab-technology/

15LECTURE NO.10



R.C.C. SLABS- waffle slabA waffle slab gets its name for its appearance as itvisually resembles its namesake, the food. Waffle slab isa reinforced concrete roof or floor containing squaregrids with deep sides. This type of slab is used inconstruction projects needing intense strength toweight ratios. Waffle slab is a popular option forcommercial construction work such as industrialbuilding projects, bridges and others needing extrastability.

http://civilengineersforum.com/waffle-slab/

16LECTURE NO.10



RIBBED SLAB•A ribbed slab, giving considerable extra strength onone direction.

On

the

bas

iso

fP

RO

FILE

17LECTURE NO.10



ADVANTAGES- RIBBED AND WAFFLED SLAB

• Flexible• Relatively light, therefore less

foundation costs and longer spans are economic

• Speed of construction• Fairly slim floor depths

On

the

bas

iso

fP

RO

FILE

Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent flat slab, reducing the extend of foundations. They provide a very good form where slab vibration is an issue, such as laboratories and hospitals.Ribbed slabs are made up of wide band beams running between columns with equal depth narrow ribs spanning the orthogonal direction. A thick top slab completes the system.Waffle slabs tend to be deeper than the equivalent ribbed slab. Waffle slabs have a thin topping slab and narrow ribs spanning in both directions between column heads or band beams. The column heads or band beams are the same depth as the ribs.

• Robustness• Excellent vibration control• Thermal mass• Good for services integration• Durable finishes• Fire resistance

18LECTURE NO.10



R.C.C. SLABS- failure

19LECTURE NO.10



R.C.C. SLABS- cracking of slab

20LECTURE NO.10



R.C.C. SLABS- damp or wet floor slab

LECTURE NO.9



STRUCTURES

SALK

INSTITUTE

24

http://bp0.blogger.com/_LK6L0q6OTGQ/RuQJEe6p4bI/AAAAAAAAAVQ/lLW4SCsKz98/s1600-h/structure+copy.jpg

http://img.groundspeak.com/waymarking/9b2f89b5-ab8f-4b97-b71b-90053fa5bd1b.jpg

Salk Institute, La Jolla

Architect: Louis Kahn

Engineer: Komendant and Dubin

Perspective section and photo

Chord depth varies with global

shear

25

28

S.No Structural Element L/D Ratio Span

1 RCC GRID 1/13- 1/14

2 SKEW GRID 1/40- 1/60

3 2 WAY SLAB 33 - 40

4 2 WAY BEAM & SLAB 45-55

5 1 WAY SLAB 24-36

6 1 WAY RIBBED SLAB 24-36

7 RCC BEAMS 16-26

8 WAFFLE SLAB 28-30

LECTURE NO.9



SLABS

HOMEWORK/ REVISION/ QUESTIONS:

LSAD : AD01 : ARCHITECTURE LECTURE NO. Slide No.27

slabs by rhythm murgai

Education