A

Training Report

On

Construction of a Residential building

Submitted in partial fulfilment of the

requirement for the award of the degree of

BACHELOR OF TECHNOLOGY

A BALA MURALI

Reg No.: 139104256

DEPARTMENT OF CIVIL ENGINEERING

MANIPAL UNIVERSITY JAIPUR

Session 2016-17

MANIPAL UNIVERSITY JAIPUR

DEPARTMENT OF CIVIL ENGINEERING

Date:26-9-16

MANIPAL UNIVERSITY JAIPUR

DEPARTMENT OF CIVIL ENGINEERING

Date: 14-09-2016

CERTIFICATE

This is to certify that Mr. BALA MURALI Reg No. 139104256 has submitted the training

report entitled “CONSTRUCTION OF RESIDENTIAL BUILDING” in partial fulfillment

for the award of the degree of Bachelor of Technology in Civil Engineering, Manipal

University Jaipur, during the academic session 2016-17. The report has been prepared as per

the prescribed format and is approved for submission and presentation.

Mr. Sanchit Anand

Assistant Professor,

Dept of Civil Engineering

Manipal University Jaipur

(Prof. Anil Dutt Vyas)

HOD,

Dept of Civil Engineering

Manipal University Jaipur

(On company letterhead)

Date:

CERTIFICATE FROM COMPANY

ACKNOWLEDGMENTS

The internship opportunity I had with Indian Railways was a great chance for learning and

professional development. Therefore, I consider myself as a very lucky individual as I was provided

with an opportunity to be a part of it. I am also grateful for having a chance to meet wonderful people

and professionals who led me though this internship period.

I express my deep sense of gratitude to Prof. Anil Datt Vyas, Head of the Department, Department of

Civil Engineering, MUJ for providing all the facilities to make this report a success. And i am also

extremely grateful to Mr.Sanchit Anand, Assistant Professor, MUJ for providing me with the

necessary guidance and support at every stage of the project.

Bearing in mind previous I am using this opportunity to express my deepest gratitude and special

thanks to the Mr. Lakshman Singh (Sr. DEN/Co-ord) who in spite of being extraordinarily busy

with his duties, took time out to hear ,guide and allowing me to carry out my project at their esteemed

organization and extending during the training.

I express my deepest thanks to Mrs. Meena (ADEN Genl (Works) SBC) for taking part in useful

decision & giving necessary advices and guidance and arranged all facilities to make life easier. I

choose this moment to acknowledge her contribution gratefully.

It is my radiant sentiment to place on record my best regards, deepest sense of gratitude to

Mr.Guruswamy and Mr.Vaithianathan Muthian for their careful and precious guidance which

were extremely valuable for my study both theoretically and practically.

I perceive as this opportunity as a big milestone in my career development. I will strive to use gained

skills and knowledge in the best possible way, and I will continue to work on their improvement, in

order to attain desired career objectives. Hope to continue cooperation with all of you in the future,

Sincerely,

A BALA MURALI

Reg. no.139104256

Civil Engineering Department

ABSTRACT

In this project, a successful attempt has been made to build a residential apartment building with cost

efficient Rainwater Harvesting System and a water storage system in the city of Bengaluru in the state

Karnataka. In a city like Bengaluru with a very rich rainfall, It is essential to have a proper Rainwater

harvesting system in a building. This report not just concentrates on the Rainwater Harvesting system

of the building but also, the construction of different structural elements like, Slabs and columns.

For the rainwater Harvesting, Recharge trench method has been used. And, the slab and columns are

constructed by in-situ method.

This report helps identifying suitable Rainwater Harvesting Technique that can be adopted for storing

water from a relatively large catchment and also the basic understanding of construction of Slabs and

columns.

CONTENTS

Acknowledgement i

Abstract ii

Table of contents 1

List of figure 4

1. INTRODUCTION 6

1.1 SOUTH WESTERN

RAILWAYS

6

1.2 NEED FOR THE PROJECT 6

1.3 LOCATION OF THE

PROJECT

7

1.4 OBJECTIVE OF THE

STUDY

7

1.5 TYPICAL FLOOR PLAN 8

1.6 ADVANTAGES OF THE

PROJECT

9

1.7 LIMITATIONS OF THE

STUDY

9

2. RAINWATER HARVESTING 10

2.1 INTRODUCTION 10

2.2 NEED FOR RAINWATER

HARVESTING

10

2

2.3 ADVANTAGES OF

RAINWATER

HARVESTING

10

2.4 RAINWATER

HARVESTING IN INDIA

11

2.5 COMPONENTS OF

RAINWATER

HARVESTING SYSTEM

11

2.6 ROOFTOP RAINWATER

HARVESTING

TECHNIQUES

2.6.1 Recharge Pit

2.6.2 Recharge Trench

2.6.3 Tube Wells

2.6.4 Trench with

recharge wells

12

12

13

14

15

2.7 DATA COLLECTION,

DESIGN &

EVALUATION

16

3. WATER SUMP 18

3.1 INTRODUCTION 18

3.2 CONSTRUCTION 19

4. RCC SLAB 23

4.1 INTRODUCTION 23

4.2 CLASSIFICATION OF

SLABS

24

3

4.3 DETAILING

REQUIREMENTS

25

4.4 SLAB CHOSEN FOR

CONSTRUCTION

26

4.5 CONSTRUCTION 26

5. RCC COLUMNS 30

5.1 INTRODUCTION 30

5.2 CLASSIFICATION OF

COLUMNS

31

5.3 TYPES OF

REINFORCEMENT

32

5.4 CONSTRUCTION 32

6. CONCLUSION 36

7. REFERENCES 37

8. ANNEXURE- I 38

9. ANNEXURE- II 40

10. ANNEXURE- III 42

11. ANNEXURE- IV 43

4

LIST OF FIGURES

Figure No Figure Title Page No

Fig. 1.1 Typical Floor Plan 8

Fig. 2.1 Recharge Pit 12

Fig. 2.2 Recharge trench 13

Fig. 2.3 Tube Wells 14

Fig. 2.4 Trench with recharge well 15

Fig. 3.1 Typical Rainwater Harvesting Detail 18

Fig. 3.2 Water Sump 19

Fig. 3.3 Mat or Raft Foundation 20

Fig. 3.4 Distance Block 20

Fig. 3.5 Water Sump (2) 22

Fig. 4.1 Slab 23

Fig. 4.2 One-way slab 24

Fig. 4.3 Two-way slab 25

Fig. 4.4 Shuttering for Slab 27

Fig. 4.5 Pooling 28

Fig. 5.1 Cross-sectional diagram of a column 30

Fig. 5.2 Column reinforcement 33

Fig. 5.3 Column before removing shuttering 34

Fig. 5.4 Column after removing shuttering 35

Fig. A1.1 Reinforcement of the top slab of Water Sump 38

Fig. A1.2 Reinforcement of the bottom slab of Water Sump 39

Fig. A2.1 Reinforcement of the short wall of Water Sump 40

5

Fig. A2.2 Reinforcement of the long wall of Water Sump 41

Fig. A3.1 Bar bending scheme of Water Sump 42

Fig. A4.1 Cross-sectional Diagram Of Water Sump 43

Fig. A4.2 Water Sump Plan 44

6

Chapter-1

INTRODUCTION

The basics needs of human existences are food, clothing’s & shelter. From times immemorial man has

been making efforts in improving their standard of living. The point of his efforts has been to provide

an economic and efficient shelter. The possession of shelter besides being a basic, used, gives a feeling

of security, responsibility and shown the social status of man.

Every human being has an inherent liking for a peaceful environment needed for his pleasant living,

this object is achieved by having a place of living situated at the safe and convenient location, such a

place for comfortable and pleasant living requires considered and kept in view.

• A Peaceful environment,

• Safety from all natural source & climate conditions,

• General facilities for community of his residential area.

The engineer has to keep in mind the municipal conditions, building bye laws, environment, financial

capacity, water supply, sewage arrangement, provision of future, aeration, ventilation etc., in

suggestion a particular type of plan to any client.

1.1 SOUTH WESTERN RAILWAYS:

The South Western Railway is one of the 17 railway zones in India. It is headquartered at Hubballi and

comprises 3 divisions namely Hubli, Mysuru, and Bengaluru. The 4th division at Gulbarga will come

up shortly and preparations of work has already begun. The zone came into existence on 1 April 2003.

1.2 NEED FOR THE PROJECT:

The present housing isn’t enough to accommodate the current and foreseen employees working in the

railways and so, there is a dire need for new buildings. And many of the current employees are already

residing in housing societies elsewhere.

There is a need for five (G+2) type 3 quarters and one (G+5) type 5 quarters

7

1.3 LOCATION OF THE PROJECT:

Location : Railway Cantonment, Jayamahal

City : Bangalore

State : Karnataka

Country : India

1.3 OBJECTIVE OF THE STUDY

The primary objective of my study is to learn the practical approach in construction and the human

factors that are involved i.e the social and technical interaction that the engineer has to deal with.

The specific objectives are as follows:

1. To analyze how a government organization plans and executes a project

2. To analyze proper method for Rainwater Harvesting for the building

3. To study the Rainwater harvesting system and choosing and designing the proper storage system

4. A practical approach to the construction of slabs and columns

8

1.4 TYPICAL FLOOR PLAN

Fig. 1.1 Typical Floor Plan

9

1.5 ADVANTAGES OF THE PROJECT

1. This project will solve the housing shortage for the employees

2. With such high rainfall in Bangalore, there will be almost no water crisis with Rainwater

harvesting installed.

3. These apartment buildings comes pre-connected to water sumps where harvested water and the

supply water can be stored before being pumped to the overhead tank.

4. This project will be on of multiple projects that are being constructed in the Bangalore region

so, the transportation of goods will be very cost efficient.

1.6 LIMITATIONS OF THE STUDY

The study is limited to this particular residential building alone. The factors affecting the design may

vary due to location, cost, client’s requirements.

10

Chapter-2

RAINWATER HARVESTING

2.1 : INTRODUCTION

Rainwater harvesting is a technique of collection and storage of rainwater into natural reservoirs or

tanks, or the infiltration of surface water into subsurface aquifers (before it is lost as surface runoff).

One method of rainwater harvesting is rooftop harvesting. With rooftop harvesting, most any surface

— tiles, metal sheets, plastics, but not grass or palm leaf — can be used to intercept the flow of

rainwater and provide a household with high-quality drinking water and year-round storage. Other

uses include water for gardens, livestock, and irrigation, etc.

2.2 NEED FOR RAINWATER HARVESTING

1. To overcome the inadequacy of surface water to meet our demands.

2. To arrest decline in ground water levels.

3. To enhance availability of ground water at specific place and time and utilize rain water for

sustainable development.

4. To increase infiltration of rain water in the subsoil this has decreased drastically in urban areas

due to paving of open area.

5. To improve ground water quality by dilution.

6. To increase agriculture production.

7. To improve ecology of the area by increase in vegetation cover etc.

2.3 ADVANTAGES OF RAINWATER HARVESTING

1 . The cost of recharge to sub-surface reservoir is lower than surface reservoirs.

2 . The aquifer serves as a distribution system also.

3. No land is wasted for storage purpose and no population displacement is involved.

4. Ground water is not directly exposed to evaporation and pollution.

5. Storing water under ground is environment friendly.

6. It increases the productivity of aquifer.

7. It reduces flood hazards.

11

2.4 RAINWATER HARVESTING IN INDIA

The New Delhi-based Centre for Science and Environment estimates that merely capturing the rain

water and run off on 2 per cent of India’s land area could supply 26 gallons of water per person.

Karnataka: In Bangalore, it is mandatory for adoption of rain water harvesting for every owner or the

occupier of a building having the roof area measuring 18.3 m X 12.2 m and above and for newly

constructed building measuring 9.1 m X 12.2 m and above dimension.

Tamil Nadu: In the state of Tamil Nadu, rainwater harvesting was made compulsory for every building

to avoid groundwater depletion. It gave excellent results within five years, and every state took it as role

model. Since its implementation, Chennai saw a 50 percent rise in water level in five years and the water

quality significantly improved.

Rajasthan: In Rajasthan, rainwater harvesting has traditionally been practiced by the people of the Thar

Desert. There are many ancient water harvesting systems in Rajasthan, which have now been revived.

Water harvesting systems are widely used in other areas of Rajasthan as well, for example the chauka

system from the Jaipur district.

2.5 COMPONENTS OF RAINWATER HARVESTING SYSTEM

Catchments

The surface that receives rainfall directly is the catchment of rainwater harvesting system. It may be

terrace, courtyard, or paved or unpaved open ground. The terrace may be flat RCC/stone roof or

sloping roof.Therefore, the catchment is the area, which actually contributes rainwater to the

harvesting system.

Transportation

Rainwater from rooftop should be carried through down take water pipes or drains to

storage/harvesting system. Water pipes should be UV resistant (ISI HDPE/PVC pipes) of required

capacity. Water from sloping roofs could be caught through gutters and down take pipe. At terraces,

mouth of the each drain should have wire mesh to restrict floating material

First Flush

First flush is a device used to flush off the water received in first shower. The first shower of rains

needs to be flushed-off to avoid contaminating storable/rechargeable water by the probable

contaminants of the atmosphere and the catchment roof. It will also help in cleaning of silt and other

material deposited on roof during dry seasons Provisions of first rain separator should be made at

outlet of each drainpipe.

12

Filter

There is always some skepticism regarding Roof Top Rainwater Harvesting since doubts are raised

that rainwater may contaminate groundwater. There is remote possibility of this fear coming true if

proper filter mechanism is not adopted. Secondly all care must be taken to see that underground sewer

drains are not punctured and no leakage is taking place in close vicinity. Filters are used fro treatment

of water to effectively remove turbidity, colour and microorganisms. After first flushing of rainfall,

water should pass through filters. A gravel, sand and ‘netlon’ mesh filter is designed and placed on top

of thestorage tank. This filter is very important in keeping the rainwater in the storage tank

2.6 ROOFTOP RAINWATER HARVESTING TECHNIQUES

Recharge pit

Fig. 2.1 Recharge Pit

In alluvial areas where permeable rocks are exposed on the land surface or are located at very

shallow depth, rain water harvesting can be done through recharge pits.

The technique is suitable for buildings having a roof area of 100 sq.m. These are constructed

for recharging the shallow aquifers.

Recharge Pits may be of any shape and size. They are generally constructed 1 to 2 m. wide and

2 to 3 m deep. The pits are filled with boulders (5-20 cm), gravels (5-10mm) and coarse sand

(1.5- 2mm) in graded form. Boulders at the bottom, gravels in between and coarse sand at the

top so that the silt content that will come with runoff water will be deposited on the top of the

13

coarse sand layer and can easily be removed. For smaller roof area, pit may be filled with

broken bricks/ cobbles.

A mesh should be provided at the roof so that leaves or any other solid waste / debris is

prevented from entering the pit. A desilting /collection chamber may also be provided at the

ground to arrest the flow of finer particles to the recharge pit.

The top layer of sand should be cleaned periodically to maintain the recharge rate.

By-pass arrangement is to be provided before the collection chamber to reject the first showers.

Recharge trench

Fig. 2.2 Recharge Trench

Recharge trenches are suitable for buildings having roof area of 200-300 sq. m. and where

permeable strata is available at shallow depths.

Trench may be 0.5 to 1 m wide, 1 to 1.5m. deep and 10 to 20 m. long depending upon

availability of water to be recharge.

These are back filled with boulders (5-20cm), gravel (5-10 mm) and coarse sand (1.5-2 mm) in

graded form – boulders at the bottom, gravel in between and coarse sand at the top so that the

silt content that will come with runoff will be coarse sand at the top of the sand layer and can

easily be removed.

14

A mesh should be provided at the roof so that leaves or any other solid waste/debris is

prevented from entering the trenches and a desilting/collection chamber may also be provided

on ground to arrest the flow of finer particles to the trench.

By-pass arrangement is to be provided before the collection chamber to reject the first showers.

The top layer of sand should be cleaned periodically to maintain the recharge rate.

Tube wells

Fig. 2.3 Tube Wells

In areas where the shallow aquifers have dried up and existing tubewells are tapping deeper

aquifer, rain water harvesting through existing tubewell can be adopted to recharge the deeper

aquifers.

PVC pipes of 10 cm dia are connected to roof drains to collect rainwater. The first roof runoff

is let off through the bottom of drainpipe. After closing the bottom pipe, the rainwater of

subsequent rain showers is taken through a T to an online PVC filter. The filter may be

provided before water enters the tubewells. The filter is 1 –1.2 m. in length and is made up of

PVC pipe. It’s diameter should vary depending on the area of roof, 15 cm if roof area is less

than 150 sq m and 20 cm if the roof area is more. The filter is provided with a reducer of 6.25

cm on both the sides. Filter is divided into three chambers by PVC screens so that filter

material is not mixed up. The first chamber is filled up with gravel (6-10mm), middle chamber

with pebbles (12-20 mm) and last chamber with bigger pebbles (20-40 mm).

15

If the roof area is more, a filter pit may be provided. Rainwater from roofs is taken to

collection/desilting chambers located on ground. These collection chambers are interconnected

as well as connected to the filter pit through pipes having a slope of 1:15. The filter pit may

vary in shape and size depending upon available runoff and are back-filled with graded

material, boulder at the bottom, gravel in the middle and sand at the top with varying thickness

(0.30-0.50m) and may be separated by screen. The pit is divided into two chambers, filter

material in one chamber and other chamber is kept empty to accommodate excess filtered

water and to monitor the quality of filtered water. A connecting pipe with recharge well is

provided at the bottom of the pit for recharging of filtered water through well.

Trench with recharge well

Fig. 2.4 Trench with recharge well

In areas where the surface soil is impervious and large quantities of roof water or surface

runoff is available within a very short period of heavy rainfall, the use of trench/ pits is made to

store the water in a filter media and subsequently recharge to ground water through specially

constructed recharge wells.

This techniques is ideally suited for area where permeable horizon is within 3m below ground

level.

16

Recharge well of 100-300 diameter is constructed to a depth of at least 3 to 5 m below the

water level. Based on the lithology of the area, well assembly is designed with slotted pipe

against the shallow and deeper aquifer.

A lateral trench of 1.5 to 3m width and 10 to 30 m length, depending upon the availability of

water is constructed with the recharge well in the centre.

The number of recharge wells in the trench can be decided on the basis of water availability

and local vertical permeability of the rocks.

The trench is backfilled with boulders, gravels and coarse sand to act as a filter media for the

recharge wells.

If the aquifer is available at greater depth say more than 20 m, a shallow shaft of 2 to 5 m

diameter and 3-5 metres deep may be constructed depending upon availability of runoff. Inside

the shaft a recharge well of 100-300 mm dia is constructed for recharging the available water

to the deeper aquifers. At the bottom of the shaft a filter media is provided to avoid choking of

recharge well.

So, we have decided to go with the recharge trench system. As the catchment area is more than 200 sq

meter

2.7 DATA COLLECTION, DESIGN & EVALUATION

2.7.1 Computation of Discharge from Rainfall

The area of the catchment (Roof) : 250 sq m

Peak Daily Rainfall Rainfall : 181mm

To find the discharge from the rainfall in the catchment of 250 sq m can be compured by The

Rational equation. It is the simplest method to determine peak discharge from drainage basin

runoff. It is not as sophisticated as the SCS TR-55 method, but is the most common method used

for sizing sewer systems.

Rational Equation: Q=ciA

The Rational equation requires the following units:

Q = Peak discharge

17

c = Rational method runoff coefficient

i = Rainfall intensity,

A = Drainage area

Value of coefficient of runoff (c) for roof: 0.75 - 0.95

Q= (0.85 x 250 x 0.181)

Q= 38.144 cu. M (38000 liters )

There are a total of 5 roofs (5 quarters) so,

Q = 5 x 38000

Q = 190720 liters

Providing a factor of safety of 1.3,

Q= 190720 x 1.3

Q= 247936 liters

This will be the volume for which we will be designing the water sump (Discussed in the next

chapter).

2.7.2 Design of a recharge trench

The methodology of design of a recharge trench is similar to that for a settlement tank. The

difference is that the water-holding capacity of a recharge trench is less than its gross volume

because it is filled with porous material. A factor of loose density of the media (void ratio) has to

be applied to the equation. The void ratio of the filler material varies with the kind of material

used, but for commonly used materials like brickbats, pebbles and gravel, a void ratio of 0.5 may

be assumed.

Assuming a void ratio of 0.5, the required capacity of a recharge tank

= (250 x 0.181 x 0.85)/0.5

= 76.925 cu. m. (76925 liters)

18

Chapter-3

WATER SUMP

3.1 INTRODUCTION

A sump is an underground (or partially underground) tank that is popular in India and mainly

southern India. It is usually used for large water tank storage and can be built cheaply using

cement-like materials. It is usually part of a rainwater harvesting system, where the rainwater gets

channeled into the tank, then pumped out for use.

Fig. 3.1 Typical Rainwater Harvesting Detail

In Bangalore, water will be purchased from private water tankers and stored to be used for

construction. One estimate says there a million sumps in the city alone with an average capacity of

6000 litres. This means that the water storage capacity created is a staggering 6000 million litres.

The city gets in about 1000 million litres every day. Added to the fact that there is about 1000

million litres stored in overhead tanks the water storage by the city far outstrips that created by the

19

utility.

Once the construction is completed the very same sump tank will be used to store the intermittent

supply from the water utility. From here a pump will send it to the overhead tank to be reticulated

by gravity to all the water points in the building.

Usually the sump tank is located in the North East corner of the site, especially for those who

believe in Vaastu. The overhead tank is located in the South West for that is supposed to be the

highest point of a building. Beliefs aside there are many technical things that should be carefully

thought through to ensure that the sump delivers efficiently what it is supposed to.

3.3 CONSTRUCTION

Fig. 3.2 Water Sump

Here, we have chosen to use mat or raft foundation as it can hold the huge amount of hydrostatic

force.

Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area

of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact

area depending on the bearing capacity of the soil underneath. The reinforcing bars runs normal to

each other in both top and bottom layers of steel reinforcement.

The raft slab generally projects for a distance of 30 cm. to 45cm. on all the sides of the outer walls

of the structure as such the area of excavation is slightly more than the area of the structure itself.

The excavation is made to the required depth and the entire excavated area is well consolidated.

20

This surface, when dry, provides the base upon which the raft or mat slab is laid. All the

precautions that are necessary to be observed during the reinforced concrete construction are

strictly adhered to and further construction is started only after the curing of the raft has been fully

done.

Fig. 3.3 Mat or Raft Foundation

There are basically two parts of a mat. Top mat and Bottom mat. And there is multiple identical

distance block placed in between them to maintain clearance.

Fig. 3.4 Distance block

21

The sump should be based on firm earth and with a good bed concrete. If the soil below is clayey

or non-homogeneous it is better to build a RCC raft slab below. The side walls should not be

compromised on and should be with good brick work using a nine inch wall. Alternately concrete

blocks or hollow concrete blocks of good quality can be used. In high water table areas or areas of

loose soil both sides of the wall should be plastered. The inside of the sump tank wall should be

plastered with a waterproof compound on a wire mesh base. This will ensure that the sump tank

does not leak. After it is built the tank should be filled with water and checked that there is no

leak. Any leak should be detected and fixed immediately.

Sump tanks are extremely unsafe spots on a site especially for children of construction workers

and for others. They should immediately have a cover slab cast with an inspection cover securely

locked. The sump cover should be rust proof. Aluminum covers are now available which are

excellent.

The other things to remember are to use a submersible pump which is energy efficient. The

submersible pump will save space being inside the sump. The pipeline from the sump to the

overhead tank should be as straight as possible and with as few bends as possible. PVC or GI pipes

of the right gauge and size should be used.

In Bangalore, the sump can also double up as a rainwater harvesting structure thus being multi-

purpose in use. During the rains rainwater and during the non-rainy season water from other

sources can be stored.

Now after completing all the connections, Shuttering is placed in required distances (That is the

reason for the gap left in the picture given below)

22

Fig. 3.5 Water sump (2)

And once the shuttering is applied, poar the concrete into it and remove the shuttering after 28

days.

23

Chapter-4

RCC Slab

4.1 Introduction

A slab is a flat two dimensional planar structural element having thickness small compared to its other

two dimensions. It provides a working flat surface or a covering shelter in buildings. It primarily

transfer the load by bending in one or two directions. Reinforced concrete slabs are used in floors,

roofs and walls of buildings and as the decks of bridges. The floor system of a structure can take many

forms such as in situ solid slab, ribbed slab or pre-cast units. Slabs may be supported on monolithic

concrete beam, steel beams, walls or directly over the columns. Concrete slab behave primarily as

flexural members and the design is similar to that of beams.

A Reinforced Concrete Slab is the one of the most important component in a building. It is a structural

element of modern buildings. Slabs are supported on Columns and Beams.

RCC Slabs whose thickness ranges from 10 to 50 centimetres are most often used for the construction

of floors and ceilings.

Fig. 4.1 Slab

24

4.2 Classification of Slabs

1. Based of shape: Square, rectangular, circular and polygonal in shape.

2. Based on type of support: Slab supported on walls, Slab supported on beams, Slab supported

on columns (Flat slabs).

3. Based on support or boundary condition: Simply supported, Cantilever slab, Overhanging

slab, Fixed or Continues slab.

4. Based on use: Roof slab, Floor slab, Foundation slab, Water tank slab.

5. Basis of cross section or sectional configuration: Ribbed slab /Grid slab, Solid slab, Filler

slab, Folded plate

6. Basis of spanning directions :

One way slab – Spanning in one direction

Two way slab _ Spanning in two direction

One Way Slab

One way slab is supported on two opposite side only thus structural action is only at one direction.

Total load is carried in the direction perpendicular to the supporting beam. If a slab is supported on all

the four sides but the ratio of longer span (l) to shorten span (b) is greater than 2, then the slab will be

considered as one way slab. Because due to the huge difference in lengths, load is not transferred to

the shorter beams. Main reinforcement is provided in only one direction for one way slabs.

4.2 One-way slab

25

Two Way Slab

Two way slabs are the slabs that are supported on four sides and the ratio of longer span (l) to shorter

span (b) is less than 2. In two way slabs, load will be carried in both the directions. So, main

reinforcement is provided in both direction for two way slabs.

Fig. 4.3 Two-way slab

4.3 Detailing Requirements as per (IS 456:2000)

Nominal Cover :

For Mild exposure – 20 mm

For Moderate exposure – 30 mm

However, if the diameter of bar do not exceed 12 mm, or cover may be reduced by 5 mm.

Thus for main reinforcement up to 12 mm diameter bar and for mild exposure, the nominal

cover is 15 mm

26

Minimum reinforcement : The reinforcement in either direction in slab shall not be less

than

• 0.15% of the total cross sectional area for Fe 250 steel

• 0.12% of the total cross sectional area for Fe 415 & Fe 500 steel.

Spacing of bars : The maximum spacing of bars shall not exceed

• Main Steel – 3d or 300 mm whichever is smaller

• Distribution steel –5d or 450 mm whichever is smaller

Where, ‘d’ is the effective depth of slab.

Maximum diameter of bar: The maximum diameter of bar in slab, shall not exceed D/8,

where D is the total thickness of slab.

4.4 Slab chosen for construction

In this project, ONE WAY CONTINUOUS SLAB has been chosen. Here, slabs are spanning in one direction

and continuous over supports are called one way continuous slabs.These are idealised as continuous beam of

unit width. For slabs of uniform section which support substantially UDL over three or more spans which do

not differ by more than 15% of the longest, the B.M and S.F are obtained using the coefficients available in

Table 12 and Table 13 of IS 456-2000. For moments at supports where two unequal spans meet or in case

where the slabs are not equally loaded, the average of the two values for the negative moments at supports may

be taken

4.5 Construction

A concrete slab can be cast in two ways. It could either be

i) Prefabricated

ii) Cast in situ.

Prefabricated concrete slabs are cast in a factory and then transported to the site ready 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 correct

dimensions to avoid trouble with the fitting of slabs over the supporting structure.

But, This hasn’t been done in this project as, we are building a roof slab and it will be difficult to

transport the slab to the top.

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In situ concrete slabs are built on the building site using formwork. Formwork is a box-like setup in

which concrete is poured for the construction of slabs.

1. Reinforcing steel is placed

2. Shutterings are placed in position

Fig. 4.4 Shuttering for slab

The formwork should be as per ( I S : 14687-1999). To retain concrete, formwork or centering and

shuttering is required, which provides the support to the wet concrete until it has gained sufficient

strength to be self supporting. The formwork or centering and shuttering used are from the material like

timber, plywood, metal or other as per site condition and requirement.

The shuttering / formwork should be so strong and rigid to prevent any deflection and support the load

of concrete placed on it and it is water tight to prevent the loss of cement mix water from concrete mix.

At the time of designing the slab, it is consider that concrete is strong in compressive strength but weak

in tensile strength, so make the structure safe against the tensile stress, steel bars are provided.

Formwork differs with the kind of slab. For a ground slab, the form-work may consist only of sidewalls

pushed into the ground whereas for a suspended slab, the form-work is shaped like a tray, often

supported by a temporary scaffold until the concrete sets.

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3. Pump-able concrete is pored into the shuttering

Pumped concrete is the concrete which is transported to heights by means of pumping using concrete

pumps. This method is used where large quantity of concrete work is involved at greater height, where

other means of transporting is not easy to do. Concrete pumps have been known for more than 50 years.

In modern times, large quantities of concrete can be transported by means of pumping through pipelines

over appreciable distances, often to locations that may not be easily accessible by other means of

delivery.

4. Curing of concrete by Pooling

Fig. 4.5 Pooling

Curing plays an important role on strength development and durability of concrete. Curing takes place

immediately after concrete placing and finishing, and involves maintenance of desired moisture and

temperature conditions, both at depth and near the surface, for extended periods of time. Properly cured

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concrete has an adequate amount of moisture for continued hydration and development of strength,

volume stability, resistance to freezing and thawing, and abrasion and scaling resistance.

Pooling is the best method of curing. It is suitable for curing horizontal surfaces such as floors, roof

slabs, road and air field pavements. The horizontal top surfaces of beams can also be ponded. After

placing the concrete, its exposed surface is first covered with moist hessian or canvas. After 24 hours,

these covers are removed and small ponds of clay or sand are built across and along the pavements.

The area is thus divided into a number of rectangles. The water is filled between the ponds. The filling

of water in these ponds is done twice or thrice a day, depending upon the atmospheric conditions.

Though this method is very efficient, the water requirement is very heavy. Ponds easily break and

water flows out. After curing it is difficult to clean the clay.

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Chapter-5

RCC COLUMNS

5.1 Introduction

A column is a very important component in a structure. It is like the legs on which a structure stands.

It is designed to resist axial and lateral forces and transfer them safely to the footings in the ground.

Columns support floors in a structure. Slabs and beams transfer the stresses to the columns. So, it is

important to design strong columns.

Fig. 5.1 Cross-sectional diagram of a column

The axial load carrying capacity of a column is deduced from the formula

Column design does not depend only on axial loads, but also on many other factors. There are bending

moments and tortional forces induced due to beam spans, wind loads, seismic loads, point loads and

many other factors.

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In the modern construction industry, Columns are mostly constructed by concrete; apart from that

materials such as Wood, Steel, Fibre-reinforced polymer, Cellular PVC, and Aluminium too are been

used. The type of material is been decided on the scale, coast and application of the construction.

5.2 CLASSIFICATION OF COLUMNS

1. Based on shape

Rectangle

Square

Circular

Polygon

2. Based on slenderness ratio

The ratio of the effective length of a column to the least radius of gyration of its cross section is called

the slenderness ratio.

Short RCC column, =< 10

Long RCC column, > 10

Short Steel column, =<50

Intermediate Steel column >50 & <200

Long Steel column >200

3. Based on type of loading

Axially loaded column

A column subjected to axial load and unaxial bending

A column subjected to axial load and biaxial bending

4. Based on pattern of lateral reinforcement

Tied RCC columns

Spiral RCC columns

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5.3 TYPES OF REINFORCEMENT

Longitudinal Reinforcement

Minimum area of cross-section of longitudinal bars must be atleast 0.8% of gross section area

of the column.

Maximum area of cross-section of longitudinal bars must not exceed 6% of the gross cross-

section area of the column.

The bars should not be less than 12mm in diameter.

Minimum number of longitudinal bars must be four in rectangular column and 6 in circular

column.

Spacing of longitudinal bars measures along the periphery of a column should not exceed

300mm.

Transverse reinforcement

It maybe in the form of lateral ties or spirals.

The diameter of the lateral ties should not be less than 1/4th of the diameter of the largest

longitudinal bar and in no case less than 6mm.

5.3 CONSTRUCTION

1. Column layout work:

In this stage of works the location of columns are determined practically in field. It is done by

laying rope according to grids shown in the drawing and then mark the location of columns

related to rope.

In drawing, column locations are shown related to grid-line with dimension. Practicaly, in

field, ropes are our grid-line. So we place columns related to rope-line by measuring dimension

shown in the drawing.

2. Column Reinforcement work

After marking the column locations, we then start to place reinforcement as instructed in the

structural drawing.

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Fig. 5.2 Column Reinforcement

This is normally described in the drawing like -

C1-12#16 mm⌀ and stirrup-10 mm⌀ @ 4" c/c.

That means column C1 will have 12 numbers of 16 mm diameter bar as vertical bar and 10 mm

diameter steel should be placed 4 inch center to center as stirrup.

or

C2-8#20 mm⌀ + 10#16 mm⌀ and stirrup-10 mm⌀ @ (4"+6") c/c.

This C2 column's reinforcement specification means that it'll have 8 numbers of 20 mm

diameter bar as well as 10 numbers of 16 mm diameter bar as vertical reinforcement and

(4"+6") center to center of stirrups placement means middle-half portion of clear height of

column will have 6" center to center spacing of stirrups and upper one-fourth as well as bottom

one-fourth height of column's clear height will hold stirrups at 4" center to center spacing.

There is a sheet in structural drawing which contains structural notes from structural designer.

In that drawing sheet, you'll find suggested lap length for column's steel of different diameter

bar and other important notes. You should read those before column reinforcement work.

3. Column Formwork

In building, floor height is normally kept 10 feet. If the slab has beam then we have to pour

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concrete up to beam bottom level. Suppose, beam height specified in drawing is 1'-6". So, the

casting height of our column will be 8'-6". And our formwork height will be 8'-6". But one

thing should be considered here is that dropping concrete from above 5' height isn't suggested

during pouring. Because it leads concrete segregation. So we should make one-side of column

formwork within 5 feet height range. After casting 5 feet of column, we just lift the short side

up to full-casting height of column next day.

Fig. 5.3 Column before removing the shuttering

Another way to cast column without segregation is to keep a small window at 5 feet level of

full-height formwork. After casting up to that level, close the window and cast the rest of the

column.

4. Poring Concrete

Casting column is easy. For small quantity of concrete volume we normally depend on

machine-mix concrete and for large concrete quantity we order ready-mix concrete. I would

suggest machine-mix concrete. Because, if you use moving pump with ready-mix concrete and

if you want not to exceed 5 feet height range for dropping concrete that would be difficult.

If you don't use moving pump, yet there are some problems. Suppose, you have decided to use

ready-mix concrete without pump. In that case, you have to manually unload concrete on job

35

site from ready-mix concrete truck and have to manually pour into column. That'll take long

time and you'll exceed initial setting time of concrete. As a result, concrete will lose its quality.

So it is better to cast column with machine-mix concrete.

5. Removing the shuttering

According to IS code, Shuttering for columns can be removed after appropriate amount of time

for the hardening of the concrete i.e 7-8 days

Fig. 5.4 Column after removing shuttering

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Chapter-6

CONCLUSIONS

In the brief 8-week internship in Indian Railways I have learned,

1. To read and understand schematic diagrams along with how to communicate that with the

workers

2. The planning of Rainwater harvesting system.

3. Requirements mandated by the government for rainwater harvesting.

4. To evaluate options and choose appropriate rainwater harvesting technique.

5. The basic understanding on how and why a water sump is used.

6. Safety concerns while using water sump.

37

REFERENCES

Reference / Hand Books

[1] “Irrigation and Water Power Engineering”, Laxmi Publications, Revised edition (2016), 978-

8131807637

[2] “Design for Water: Rainwater Harvesting, Stormwater Catchment, and Alternate Water Reuse”,

New Society Publishers, 978-0865715806

[3] Rainwater Harvesting, “Rainwater Harvesting”, Chandrawati Jee Shagufta, Aph Publishing

Corporation, 978-8131307588

[4] “R.C.C Designs”, B.C. Punmia, Laxmi Publications, Tenth edition, 978-8131809426

[5] “Design of Reinforced Concrete Structures”,N. Subramanian, Oxford, 978-0198086949

Web

[1] Rainwater Harvesting - http://www.rainwaterharvesting.org

[2] Rainwater Harvesting - http://theconstructor.org

[3] Rainwater Harvesting - https://wikipedia.org/

[4] Rainwater Harvesting - http://akvopedia.org

[5] Rainwater Harvesting- http://yourarticlelibrary.com

[6] Rainwater Harvesting- http://vikaspedia.in

38

ANNEXURE - I

Fig. A.1 Reinforcement of the Top Slab

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Fig. A.2 Reinforcement of the bottom slab

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ANNEXURE - II

Fig. A2.1 Reinforcement of the Short wall

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Fig. A2.2 Reinforcement of the long wall

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ANNEXURE - III

Fig. A3.1 Bar Bending Schedule

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ANNEXURE - IV

Fig. A4.1 Cross-sectional Diagram

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Fig. A4.2 Water Sump Plan