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DESIGN OF SINGLE STOREYED RESIDENTIAL BUILDING

GNIT 01

ABSTRACT

DESIGN OF SINGLESTOREYEDRESIDENTIALBUILDING

AIM OF THE PROJECT:

The aim of this project is to illustrate a design of a single storeyed

residential building in specific from first principles without the use of any design aid (except the

Code), using Limit State Method and S.I. units, conforming to IS: 456-2000.

Since, the object of this project is to illustrate the design of R.C.

members rather than analysis of a framed structure, a single storeyed structure has been taken for

design. The plan is so chosen that it incorporates design of different types of members, namely:

1. SLABS:Two-way Continuouscorners restrained (S 1-4)

2. BEAMS:Continuous with two equal spans (B1-B12)

3. COLUMNS:Axially Loaded (C1-C9)

4. COLUMN FOOTINGS:Axially loaded isolated sloped footing.

DATA:

1. TYPE: Single Storeyed R.C. Framed Structure2. PLAN: As shown in Figure 2.3. USE: Residential building.4. GEOMETRIC DETAILS:

Floor to floor Height : 3.2 Metres

Height of Plinth : 0.6 Metre above ground level

Depth of Foundation : 0.72 Metre above ground level

5. LOADS :Roof: Live Load : 1.5 kN/m

2

Floor finish : 1.75 kN/m2

6. SPECIFICATIONS FOR MATERIALS AND BUILDING COMPONENTS:Roof : R.C. Slab, flat type with waterproofing course

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GNIT 02

Walls : Brick Masonry 230mm thick duly plastered

Concrete : Grade M15

Steel : Grades, MainFe415, SecondaryFe250

7. FOUNDATION: Bearing capacity of Soil : 150 kN/m28. ASSUMPTIONS FOR DESIGN: Slab simply supported over beams and beams

simply supported over columns.

9. DESIGN PHILOSOPHY:Limit State Method conforming to IS: 4562000.10. EXPOSURE CONDITIONS :Mild environment.

FIGURE 1: STRUCTURAL PLAN

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GNIT 03

FIGURE 2: PLAN OF THE RESIDENTIAL BUILDING

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GNIT 04

1. INTRODUCTION

The basics needs of human existences are food, clothings & shelter. From time immemorialman 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 need, 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 objective is achieved by having a place of living situated at the safe and convenient

location, and such a place for comfortable and pleasant living requirements are 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., while suggesting a particular type of plan to any client.

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GNIT 05

2. DEMAND OF HOUSES

The house is the first unit of the society and it is the primary unit of human habitation.

The house is built to grant the protection against wind, weathers, and to give insurance

against physical insecurity of all kinds.

The special features of the demand for housing consists of in its unique nature and

depend on the following factors.

Availability of cheap finance. Availability of skilled labours. Availability of transport facility. Cost of labours & material of construction. Predictions of future demand. Rate of interest on investment e. g., low rates of interest with facilities of long term

payment may facilities investment in housing.

Rate of population growth and urbanization. Supply of developed plots at reasonable prices. Taxation policy on real estates Town planning & environmental conditions.

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GNIT 06

3. CLASSIFICATION OF BUILDINGS BASED ON OCCUPANCY

GROUP-A RESIDENSIAL BUILDINGS

GROUP-B EDUCATIONAL BUILDINGS

GROUP-C INSTITUTIONAL BULIDINGS

GROUP-D ASSEMBLY BUILDINGS

GROUP-E BUSINESS BUILDINGS

GROUP-F MERCANTILE BUILDINGS

GROUP-G INDUSTRIAL BUILDINGS

GROUP-H STORAGE BUILDINGS

GROUP-I HAZARDOUS BUILDINGS

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GNIT 07

RESIDENTIAL BUILDINGS:

These building include any building in which sleeping accommodation provide for

normal residential purposes, with or without cooking and dining facilities. It includes single or

multi-family dwellings, apartment houses, lodgings or rooming houses, restaurants, hostels,dormitories and residential hostels.

EDUCATIONAL BUILDINGS:

These include any building used for school, college or day-care purposes involving

assembly for instruction, education or recreation and which is not covered by assembly

buildings.

INSTITUTIONAL BUILDINGS:

These buildings are used for different purposes, such as medical or other treatment or

care of persons suffering from physical or mental illness, diseases or infirmity, care of infants,

convalescents or aged persons and for penal detention in which the liberty of the inmates is

restricted. Institutional buildings ordinarily provide sleeping accommodation for the

occupants.

ASSEMBLY BUILDINGS:

These are the buildings where groups of people meet or gather for amusement,

recreation, social, religious, assembly halls, city halls, marriage halls, exhibition halls,

museums, places of work ship, etc.

BUSINESS BUILDINGS:

These buildings are used for transaction of business, for keeping of accounts and

records and for similar purposes, offices, banks, professional establishments, courts houses,

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GNIT 08

libraries. The principal function of these buildings is transaction of public business and

keeping of books and records.

MERCANTILE BUILDINGS:

These buildings are used as shops, stores, market, for display an sale of merchandise

either wholesale or retail, office, shops, storage service facilities incidental to the sale of

merchandise and located in the same building.

INDUSTRIAL BUILDINGS:

These are buildings where products or materials of all kinds and properties are

fabrication, assembled, manufactured or processed, as assembly plant, laboratories, dry

cleaning plants, power plants, pumping stations, smoke houses, laundries etc.

STORAGE BUILDINGS:

These buildings are used primarily for the storage or sheltering of goods, wares or

merchandise vehicles and animals, as warehouses, cold storage, garages, trucks.

HAZARDOUS BUILDINGS:

These buildings are used for the storage, handling, manufacture or processing of highly

combustible or explosive materials or products which are liable to burn with extreme rapidly

and/or which may produce poisonous elements for storage handling, acids or other liquids or

chemicals producing flames, fumes and ex plosive, poisonous, irritant or corrosive gases

processing of any material producing explosive mixtures of dust which result in the division of

matter into fine particles subjected to spontaneous ignition.

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GNIT 09

4. SELECTION OF PLOT AND STUDY

Selection of plot is very important for buildings a house. Site should be in a place where

public transport is available but not in an environment that becomes a source of inconvenience

or noisy. The conventional transportation is important not only because of need but for retention

of property value in future closely related to are transportation and shopping. One must be

understand whether there is indication of future development or not in case of undeveloped area.

The factor to be considered while selecting the building site are as follows:-

Access to park &playground. Agriculture potentiality of the land. Availability of public utility services, especially water, electricity & sewage disposal. Contour of land in relation the building cost. Cost of land. Distance from places of work. Ease of drainage. Location with respect to school, collage & public buildings. Nature of use of adjacent area. Transport facilities. Wind velocity and direction.

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GNIT 10

5. SURVEY OF THE SITE FOR PROPOSED BUILDING

Reconnaissance survey: the following has been observed during reconnaissance survey of

the site.

Site is located nearly. The site is very clear planned without ably dry grass and other throne plats over the

entire area.

No leveling is require since the land is must uniformly level. The ground is soft. Labour available near by the site. Houses are located near by the site. Detailed survey: the detailed survey has been done to determine the boundaries of the

required areas of the site with the help of theodolite and compass.

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GNIT 11

6. RESIDENTIAL BUILDING

Requirement for residential accommodation are different for different classes of

people & depends on the income &status of the individual a highly rich family with require a

luxurious building, while a poor man we satisfied with a single room house for even poorclass family.

A standard residential building of bungalow type with has drawing room, dining

room office room, guest room, kitchen room, store, pantry, dressing room, bath room, front

verandah, stair etc., for other house the number of rooms may be reduced according to the

requirements of many available.

a)LIMITATION OF BUILT UP AREA

201 to 500sq.m (241to

600sq.yd)

---- 50% of the site area.

501 to 1000sq.m (601 to 1200sq.yd) ---- 40% of the site area

More than 1000sq.m ---- 33% of the site area.

Area of plot up to 200sq.m (240sq.yd) ---- maximum permissable built up area

Ground and first ---- 60% of site area on floor only.

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GNIT 12

b)MINIMUM FLOOR AREA & HEIGHT OF ROOMS

FLOOR AREA HIEGHT (m)

LIVING 10sqm (100sqft)

(breadth min 2.7 m or 9) 3.3 (11)

KITCHEN 6sqm (60sqft) 3.0 (10)

BATH 2sqm (20sqft) 2.7 (9)

LATTRINE 1.6sqm (16sqft) 2.7 (9)

BATH & WATER CLOSET 3.6sqm (36sqft) 2.7 (9)

SERVANT ROOM 10sqm (100sqft) 3.0 (10)

GARAGE 2.5*4.8 m (8*16) 3.0 (10)

MIN. HIEGHT OF PLINTH

FOR MAIN BUILDING ------- 0.6 (2)

MIN. HIEGHT OF PLINTH FOR

SERVANT QUARTES ------- 0.3 (1)

MIN. DEPTH OF FOUNDATION ------- 0.9 (3)

THICKNESS OF WALL 20cms to 30cms ------

(9 to13.5)

DAMP PROOF COURSE 2cms to 2.5cms thick full width of

(3/4 to1) plinth wall

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GNIT 13

7.BUILDING BYE LAWS & REGULATIONS

Line of building frontage and minimum plot sizes. Open spaces around residential building. Minimum standard dimensions of building elements. Provisions for lighting and ventilation. Provisions for safety from explosion. Provisions for means of access. Provisions for drainage and sanitation. Provisions for safety of works against hazards. Requirements for off-street parking spaces. Requirements for landscaping. Special requirements for low income housing.

Size of structural elements.

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14

8. ARRANGEMENT OF ROOMS

LIVING ROOM

KITCHEN STORE ROOM BED ROOM OFFICE ROOM BATH & W C DRESSING ROOM VERANDAH STAIR CASE

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GNIT 15

LIVING ROOMS:

This is the area is for general use. Hence the living & drawing room should be planned

near the entrance south east aspects. During colder days the sun is towards the south & will

receive sunshine which is a welcoming feature. During summer sunshine is in the northern side

& entry of sunrays from southern or southeast aspects do not arise.

KITCHEN:

Eastern aspects to admit morning sun to refresh & purity the air.

READING ROOM/ CLASS ROOM:

North aspects this makes more suitable since there will be no sun from north side for

most part of the year.

BED ROOM:

Bed may also be provided with attached toilets, there size depends upon the number of

beds, they should be located so as to give privacy & should accommodate beds, chair, cupboard,

etc., and they should have north orwest southwest aspect.

BATH & W.C:

Bath and w.c are usually combined in one room & attached to the bed room and should

be well finished. This should be filled with bath tub, shower, wash-hand basin, w.c, shelves,

towels, racks brackets, etc., all of white glazed tiles. Floor should be mosaic or white glazed

files. Instead of providing all bed room with attached bath and W.C separated baths & latrines

may also be provided

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GNIT 16

VERANDAH:

There should veranda in the front as well as in the rear. The front veranda serves setting

place for male members & weighting place for visitors. The back veranda serves asa ladies

apartment for their sitting, working controlling, and kitchen works etc., veranda protect the room

against direct sun, rain & weather effect. They used as sleeping place during the summer and

rainy season & are used to keep various things veranda also give appearance to the building. The

area of a building may vary from 10% to 20% of the building.

STAIR CASE:

This should be located in an easily accessible to all members of the family, when this is

intended for visitors it should be in the front, may be on one side of veranda. It meant for family

use only, the staircase should be placed the rear. The stairs case should be well ventilated &

lighted the middle to make it easy & comfortable to climb. Rises & threads should be uniform

through to keep rhythm while climbing or descending.

Some helpful points regarding the orientation of a building are as follows:-

Long wall of the building should face north south, short wall should face.

East and west because if the long walls are provided in east facing, the wall.

Absorb more heat of sun which causes discomfort during night.

A veranda or balcony can be provided to wards east & west to keep the rooms cool.

To prevent suns rays & rain from entering a room through external doors & windows

sunshades are required in all directions.

ORIENTATION

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GNIT 17

After having selected the site, the next step is proper orientation of building. Orientation

means proper placement of rooms in relation to sun, wind, rain, topography and outlook and at

the same time providing a convenient access both to the street and back yard.

The factors that affect orientation most are as follows.

Solar heat Wind direction Humidity Rain fall Intensity of wind site condition Lightings and ventilation

SOLAR HEAT:

Solar heat means suns heat, the building should receive maximum solar radiation in

winter and minimum in summer. For evaluation of solar radiation, it is essential to know the

duration of sunshine and hourly solar intensity on exposed surfaces.

WIND DIRECTION:

The winds in winter are avoided and are in summer, they are accepted in the house to the

maximum extent.

HUMIDITY:

High humidity which is common phenomenon is in coastal areas, causes perspiration, which is

very uncomfortable condition from the human body and causes more discomfort.

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GNIT 18

RAIN FALL:

Direction and intensity of rainfall effects the drainage of the site and building and hence, it is

very important from orientation point of view.

INTENSITY OF WIND:

Intensity of wind in hilly regions is high and as such window openings of comparatively small

size are recommended in such regions.

SITE CONDITIONS:

Location of site in rural areas, suburban areas or urban areas also effects orientation, sometimes

to achieve maximum benefits, the building has to be oriented in a particular direction.

LIGHTING:

Good lighting is necessary for all buildings and three primary aims. The first is to promote the

work or other activities carried on within the building.

The second is to promote the safety of people using the buildings. The third is to create, in

conjunction to interest and of well beings.

VENTILATION:

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GNIT 19

Ventilation may be defined as the system of supplying or removing air by natural or

mechanical mean or from any enclosed space to create and maintain comfortable conditions.

Operation of building and location to windows helps in providing proper ventilation. A sensation

of comfort,reduction in humidity, removal of heat, supply of oxygen are the basic requirements

in ventilation apart from reduction of dust.

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GNIT 20

DESIGNS

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GNIT 21

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GNIT 22

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GNIT 23

SLAB DESIGN

1. Slab mark: S12. Type: two way continuous with corners restrained3.

Spans : short span = 3.94 , = 4.6.4. Trial depth: in case of a two way slab, L/d ratio for deflection criteria isrelated to short span. Since short span in this case = 3.94m is greater than

3.5m, deflection requirement is governed by clause 23.2.1 instead of clause

24.1. in the case of two way slabs the design moments are small compared to

those in one way slabs, percentage of steel required in two way slabs is, in

general, very low. Since even the live load is also small, only 0.2% steel will

be assumed.

For = 0.2% , = 1.7 = 240

= 26 .

= =3940/(1.7X26)= say 110mm

Assuming d=20 mm for Fe415,

Required D= 110+20 =130mm.

Effective depth to the outer layer of bars, = 110Effective depth to the inner layer of bars, = 100mm.

5. Loads: consider one metre width of slab.

= 1.5250.13+1.75+1.5 = 1.5 6.5 = 9.752.

6. Design moments :boundary condition no. 4Discontinuous on two adjacent edges.

= 9.75 3.94 3.94 = 152.

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GNIT 24

Span position B.M. coeff. () = KN.mShort- support 0.0537 .0537X152=8.2 KN.m

-mid span .0405 .0405X152=6.2 KN.m

Long- support .047 .047X152 =7.14 KN.m

-midspan 0.035 .035X152=5.32 KN.m

7. Check for concrete depth: = . , = 1000

= 2.76 20 415For outer bar, =2.76X1000X110X110X10=33.4 KN.m>8.2KN.m.Therefore, safe.

For inner bars, =2.76X1000X100X100X10=27.6 KN.m8. Main steel:

Required

=.

*1 1 . 1000

Location KN.m

d

mm

Reqd.Dia-spacing

mm-mm

Prov.Short span-

support

8.2 110 215 #8@230 218

-Midspan 6.2 110 161 #8@300 167

Long span-

Support

7.14 110 186.4 #8@250 200

Midspan 5.32 100 125 #8@400 125

Distribution steel: provide #8 at 320mm.

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GNIT 25

9. Check for deflection:Required at mid span of short span = 161X100/ (1000X110) =0.14 %15.36KN,ii. Short edge discontinuous:

=0.9x12.805=11.5KN

= 1252 Assuming 50% bent up to resist moment due to partial fixity, = 62.52, = 62.5100/1000110=0.06% = 0.28/2 =kbd=1.3X.28X1000X110/1000=40.04KN>11.5KN,

11.Check for development length:a.i. Long edgecontinuous: required =47x8=376mm

Available

=0.3l of slab S4 =0.3x4=1200>376mm.

Therefore, ok.

ii. Long edge-discontinuous span:Assuming 50% bars bent up, =6.2/2=3.1 KN.m, V=12.1KN = 2 + 3 for HYSD bars using 90 bend

= 2 5 + 3 8=114mm = 376 < 447. . + =1.3x3.1x1000/12.1+114=447mm)

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GNIT 27

,b.

i. Short edge continuous: required =47x8=376mmAvalable=0.3 = 0.3x4600=1380mmTherefore safeii. Short edge discontinuous: =47x8=376mm.

Assuming 50% bars bent up, = 5.32/2=2.66KN.m,V= 11.5KN

= 376 < 414 1.31 + = 1.3x2.66x1000/11.5+114 = 414mmTherefore, safe.

12.Torsion steel:a. At corners near columns C1 & C7, since slab is discontinuous over both

over the edges, full torsion steel equal to 0.75=0.75x161=120.75mm2 will be required in both directions at right anglesin each of the two meshes, one at top and the other at the bottom for a

length = /5 =3940/5=788mm.b. At corners near columns C6,C8&C2, required area of torsion steel is just

half of torsion steel in (a) above since the slab is discontinuous over only

one of the two edges at these corners.

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GNIT 28

BEAM DESIGN

1. Beam mark:B3-B42. End conditions: two span continuous beam with equal spans. Ends

simply supported

3. Span: L=3940mm each.4. Section: Assumed 230mmx380mm, d=340mm,d=40mm,=130mm.5. Loads: Maximum load 1.5x(DL+LL) and minimum load (DL only)

Type of slab: two way slab on either side. =3.94m, =4.6mDL+LL=6.5

2only DL=5

2

Equivalence factor for converting trapezoidal load into UDL

= 1 13 = =4.6/3.94=1.16, = 1 .=0.75Self-beam() =1.6KN/mWall load= nilMaximum load

=1.5(DL+LL) =1.5(1.6+ (2x0.6x6.5x3.94x0.75))=36.97KN/m =1.6+ (2x0.6x6.5x3.94x0.75)=19.33KN/m6. Design moments:

Design moments at support as well as mid span = 10

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GNIT 29

=.. = 78KN.m

=

..

. = 68.1

=36.97x4.6-68.1=101.96KN.a. At support:

= 10 = 78KN.m (0.8x36.974.6 8 )This corresponds to 20% redistribution of moment

=0.6-0.2=0.4, =0.4x340=136mmForthis,

=0.36x20x0.4x(1-0.42x0.4)x230x340x340x

10

=63.7KN.m

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GNIT 30

Therefore, = + =624+143 =767mm2

/d=40/340=0.117,Therefore, = 1.063132 = 140.3 2.

b. At mid span : = 0.7 = 0.74600 = 3200

= (32006 +6130+230) = 1544 = =0.36X20X1544X130X(340-0.42X130)X10=412.5KN.m>.=78KN.m)Therefore, <

= . 1 1 .X1544X340=653mm2

c. Detailing:Required Simple support At mid span At continuousendAt top

At bottom ----- 653

767

140.3

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GNIT 31

No.-dia at top

-dia at bottom

2#10

2#20;1#12

2#10

2#20;1#12

2#12;2#20

2#12

Prov

at top

At bottom

157.07

741.4

157.07

741.4

854.5

226.19

7. Design for shear:Since the beam is supporting a two way slab S4, the equivalent uniformly

distributed load for shear is different than that considering for blending.

The equivalence factor = = (1- )=(1- .)=0.57The total UD load on beam for shear

= 1.5(1.6+ (2x0.6x6.5x3.94x0.57))=28.7KN/ma. At continuous end:

=0.6 L=0.6x28.7x4.6=79.2KN for design moment =854.5mm2, = . =1.1%, =0.64N/mm2 = 0.64230340/1000=50.04KN. = 0.4230340/1000=31.28KN. = 50.04+31.28 = 81.32 > = 79.2Therefore, minimum stirrups are sufficient. Provide 6mm dia at130mm c/c.

b. At simply supported end: = 0.4528.74.6 = 59.41

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GNIT 32

=2#20;1#12=741.4mm2 ,=100X741.4/(230X340)=0.95% , = 0.57N/mm2

=0.57x230x340/1000=44.57KN

. =31.28KN, therefore, .=44.57+31.28=75.85KN < .Therefore, minimum stirrups are sufficient.

Provide 6mm-2 legged stirrups at 130mm c/c.8. Check for deflection:

% = =. =0.14%=0.58x415x653/741.4=212N/mm2, = 0.95/2 =230/1544=0.15

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GNIT 33


simply supported

3. Span: L=3940mm each.4. Section: Assumed 230mmx380mm, d=340mm,d=40mm,=130mm.5. Loads: self + parapet wall +S1(trapezoidal)

Maximum load 1.5x(DL+LL) and minimum load (DL only)

Type of slab: two way slab on one side. =3.94m, =4.6mDL+LL=6.5 2 only DL=5 2 Equivalence factor for converting trapezoidal load into UDL

= 1 13 = =4.6/3.94=1.16, = 1 .=0.75Self-beam() =1.6KN/mWall load= nil

Maximum load

=1.5(DL+LL) =1.5(1.6+ 5+(0.6x6.5x3.94x0.75))=27.18KN/m6. Design moments:


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GNIT 34

=.. = 57.5KN.m

=

.. 57.5/4.6 = 50

=27.18x4.6-50=75KN.d. At support:

= 10 = 57.5KN.m (0.8x27.184.6 8 )This corresponds to 20% redistribution of moment

=0.6-0.2=0.4, =0.4x340=136mmFor this,

=0.36x20x0.4x(1-0.42x0.4)x230x340x340x

10

=63.7KN.m>57.5KN.m

Therefore, the section will be designed as singly reinforced.

Tension steel:

= . 1 1 ..230340=549mm2

Therefore, =549mm2

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GNIT 35

e. At mid span : = 0.8 = 0.84600 = 3680

= (3680

12 +6130+230) = 1317

= =0.36X20X1317X130X(340-0.42X130)X10=352KN.m>.=57.5KN.m)Therefore, <

= . 1 1 ..X1317X340=479.3mm2f. Detailing:

Required Simple support At mid span At continuousend

At top

At bottom ----- 479.3

549

---

No.-dia at top

-dia at bottom

2#12

2#10;1#16+1#16*

2#12

2#10;1#16+1#16*

2#12;2#16*

2#10+1#16

Prov attop

At bottom

226

559

226

559

628

358



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GNIT 36


=1.5(1.6+ 5+(0.6x6.5x3.94x0.57))=23.04KN/m

c. At continuous end:=0.6 L=0.6x23.04x4.6=63.59KN for design moment

=628mm2, = =0.80%, =0.57N/mm2 = 0.57230340/1000=44.57KN

. = 0.4230340/1000=31.28KN

. = 44.57+31.28 = 75.85 > = 63.59Therefore, minimum stirrups are sufficient. Provide 6mm dia at130mm c/c.

d. At simply supported end: = 0.45 =0.45x23.04x4.6=47.69KNSince at discontinuous end is also 2#16+2#10, just as atcontinuous end, and since minimum stirrups are sufficient at

continuous end, they are sufficient at discontinuous end too.

8. Check for deflection:Actual L/d ratio=4600/340=13.5

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GNIT 37

At discontinuous end: =47.69KN on column C11. Beam mark: B9-B102. End conditions: two span continuous beam with equal spans. Ends

simply supported

3. Span: L=4600mm each.4. Section: Assumed 230mmx380mm, d=340mm,d=40mm,=130mm.5. Loads: Maximum load 1.5x(DL+LL) and minimum load (DL only)

Type of slab: two way slab on either side. =3.94m, =4.6mDL+LL=6.5 2 only DL=5 2 Equivalence factor for converting triangular load into UDL

For bending = =.. =8.54KN/m

For shear = =.. = 6.40KN/m

Self-beam() =1.6KN/mWall load= nil

Maximum load

for bending =1.5(1.6+ (2x8.54))=28.02KN/mfor shear =1.5(1.6+(2x6.40))=21.6KN/m6. Design moments:

Design moments at support as well as mid span = 10 =.. = 59.29KN.m

g. At support:= 10 = 59.29KN.m (0.8x36.974.6 8 )

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GNIT 38

This corresponds to 20% redistribution of moment

=0.6-0.2=0.4, =0.4x340=136mmFor this,

=0.36x20x0.4x(1-0.42x0.4)x230x340x340x10=63.7KN.m>59.29KN.m

Therefore, the section will be designed as singly reinforced.=. 1 1 .. x230x340=570mm2h. At mid span :

= 0.7 = 0.74600 = 3200

= (32006 +6130+230) = 1544

= =0.36X20X1544X130X(340-0.42X130)X10=412.5KN.m>.=78KN.m)Therefore, <

= . 1 1 .X1544X340=653mm2

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GNIT 39

i. Detailing:Required Simple support At mid span At continuous

end

At top

At bottom ----- 653

570

No.-dia at top

-dia at bottom

2#12

2#20;1#12

2#12

2#20;1#12

2#12+2#16*

2#10;1#16

Prov at topAt bottom

226

741.4

226

741.4

628

358



e. At continuous end:=0.6 L=0.6x21.6x4.6=59.6KN for design moment

=628mm2, = =0.80%, =0.57N/mm2 = 0.57230340/1000=44.57KN. = 0.4230340/1000=31.28KN. = 44.57+31.28 = 75.85 > = 59.6

Therefore, minimum stirrups are sufficient. Provide 6mm dia at130mm c/c.

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GNIT 40

f. At simply supported end: = 0.4521.64.6 = 44.7=2#20;1#12=741.4mm2 ,

=100X741.4/(230X340)=0.95% , = 0.57N/mm2=0.57x230x340/1000=44.57KN. =31.28KN, therefore, .=44.57+31.28=75.85KN < .Therefore, minimum stirrups are sufficient.

Provide 6mm-2 legged stirrups at 130mm c/c.8. Check for deflection:

% = =. =0.14%=0.58x415x653/741.4=212N/mm2, = 0.95/2 =230/1544=0.15

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GNIT 41


simply supported

3. Span: L=4600mm each.4. Section: Assumed 230mmx380mm, d=340mm,d=40mm,=130mm.5. Loads: self + parapet wall +S1(trapezoidal)

Maximum load 1.5x(DL+LL) and minimum load (DL only)

Type of slab: two way slab on one side.

=3.94m,

=4.6m

DL+LL=6.5 2 only DL=5 2 Equivalence factor for converting trapezoidal load into UDL = 1 13

= =4.6/3.94=1.16, = 1 .=0.75Self-beam() =1.6KN/mWall load= nil

Maximum load

=1.5(DL+LL) =1.5(1.6+ 5+(0.45x6.5x3.94x0.75))=22.86KN/m6. Design moments:


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GNIT 42

=.. = 48.37KN.mj. At support:

= 10 = 48.37KN.m (0.8x22.864.6 8 )This corresponds to 20% redistribution of moment

=0.6-0.2=0.4, =0.4x340=136mmFor this,=0.36x20x0.4x(1-0.42x0.4)x230x340x340x10=63.7KN.m>48.37KN.m

Therefore, the section will be designed as singly reinforced.

Tension steel:

= . 1 1 .. 230340=447.32mm2

Therefore, =447.32mm2k. At mid span :

= 0.8 = 0.84600 = 3680 = (368012 +6130+230) = 1317

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GNIT 43

= =0.36X20X1317X130X(340-0.42X130)X10=352KN.m>

.

=48.37KN.m)

Therefore, <

= . 1 1 ..X1317X340=402mm2l. Detailing:

Required Simple support At mid span At continuousend

At top

At bottom ----- 402

447.32

---

No.-dia at top

-dia at bottom

2#10

2#10;1#16+1#16*

2#10

2#10;1#16+1#16*

2#10;2#16*

2#10+1#16

Prov

at

top

At bottom

157

559

157

559

559

358




= 1.5(1.6+ 5+(0.6x6.5x3.94x0.57))=23.04KN/m

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GNIT 45

DESIGN OF COLUMNS

Floor to floor height=3200mm

Height of plinth above G.L= 600mm

Depth of foundation below G.L=720mm

Assuming depth of footing =300mm

Total height of column above top of footing =4220mm

Depth of shallowest beam =380mm

Unsupported length of column L= 4220-380=3840mm.

Assuming effective length = L since all columns are supported bybeams in both directions and there are transversal and longitudinalexternal walls. Actual effective length is therefore, likely to be less than L

if exact calculations are done.

Effective length of column =3840mmAssumed section bxD =230mmx230mm

Slenderness ratio / =3840/230=16.7>12Therefore, the column is slender

Allowance for slenderness = (1/-1)x100%Where, =1.25-/48 =1.25-16.7/48=0.9

Allowance for slenderness =(1/0.9-1)x100=10.9% say 11%

Factored self-weight of column = 1.5x25x.23x.23x3.84=7.6KN ~ 8KN

Maximum axial load from beams B3-B4 and B9-B10 on column C9 at

continuous end = (59.6+79.2) x2=277.6KN~278KN

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GNIT 46

= 278+8=286KN.Section: 230x230mm with 4-#12.= 452mm2i. Bending about x-axis

Smaller end moment =0 at the base as it is designed as rotationfree.

Larger end moment = moment in the column at top due to partial

fixity between beam and column is calculated as under:

Column:

=230x230x230/12=233.2x10 mm4, = 3840

= 0.75233.2103840 = 45.55103.The stiffness of 0.75I/L is taken since the lower end of the column is

rotation free.

Beam:

Section: 230x380, L= 4.6m (B9-B10), =28.02KN/m

= . = 101.6x10Distribution factor:

= :/ = 45.55/(45.55+101.6/2)=.472

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GNIT 47

= 24 = 24.7KN.m

= = = 24.7x.472=11.6KN.mInitial moment

= 0.6 +0.4 = 0.6x11.6+0.4x0=6.96KN.mMinimum eccentricity , =20mmMinimum moment, = = 286x20/1000=5.7KN.m

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GNIT 48

d/D / P/ / Chart No.0.2 0.3 0.043 0.084 4G

0.25 0.3 0.043 0.075 5G

0.226 0.3 0.043 0.079 by interpolation

=0.079x1058x0.23=19.2KN.m>13.93KN.mTherefore, safe.

iii. Bending at y-axis:In this case, external moment may be taken nearly equal to zero

because beams are on opposite sides and they are of equal spans

and carry equal loads.

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GNIT 49

DESIGN OF FOOTINGS

COMMON DATA:

Concrete grade,(mild environment) M20

Steel grade Fe415

Design constant =2.76Column section b=230mm

D=230mm

Bearing capacity of soil = 150Minimum depth of footing =150mmOffset at footing level e=75mm

I. DATAMaximum column load, =286KNDesign working load, P = /1.5=286/1.5=190.7KNColumn section = 230mmx230mm

Bearing capacity of soil =150KN/m2

II. PROPORTIONING OF BASE SIZEArea of footing required in m2 ,

=1.1P/

=1.1x190.7/150=1.39m2

Required length of footing for equal projections:= (D-b)/2 + + = since b=D

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GNIT 50

Therefore, =1.39 =1.18m=1180mmProvide length of footing =1250mmProjection = = /2=(1250-230)/2=510mmProvide width of footing

=b+2x=230+2x510=1250mmArea of footing provided,=x=1.25x1.25=1.5625m2Upward factored soil pressure (due to

)

=/=286/1.5625=183.05KN/m2III.Depth of footing from bending moment considerations

Breadth of footing at top =b+2e=230+2x75=380mmBending moment at column face parallel to x-axis

= /2=183.05x1.25x0.510x0.510/2=30KN.mLength of footing at top =D+2e=230+150=380mmBending moment at column face parallel to y-axis

= /2=183.05x1.25x0.510x0.510/2=30KN.m

(a)Required effective depth for bending about x-axis = =. =170mm

=170mm

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GNIT 51

Assuming diameter of the bar = 8mm

Effective cover for bottom bars =50+8/2=54mmEffective covers for top bars =54+8=62mmRequired depth of footing = 170+62=232mmAssume total depth =240mmEffective depth for bottom bars ==240-54=186mmEffective depth for top bars ==240-62=178mmIV.Check depth of footing from two way considerations

Perimeter at critical section =B2=2(b+D+2)=2(230+230+2x178)=1632mmEffective depth at peripheral section=D2=--Where,y2=(/2-e)y1/x1=(178/2-75)x90/(510-75)=2.89mmTherefore, D2=240-2.89-62=175.1mmm

Area resisting shear =A2= perimeterxD2=1632x175.1=285763mm

Shear resisted by concrete = = ; k=(0.5+230/230)>1 therefore k=1=0.25=0.25x20=1.118N/mm2 = =1.118x285763/1000=319.5KNDesign shear= + + =198.6(1250x1250-(230+178)(230+178))x10^-6=317.8KN

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GNIT 52

> Therefore,safe.

Area of steel and check for development length

(a)=0.85b1/=0.85x380x186/415=145mm2 = . 1 1 .x380x186=510.9mm2

12 #8, = 6002(b)0.85/=085x380x178/415=139mm2

= . 1 1 .x380x178=565mm2 12 #8, = 6002= (0.87/4 =(0.87x415/(4x1.2x1.6))x8=376mm

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GNIT 53

Shear resisted by concrete= = x=0.417x173067/1000=72.1KNShear to concrete footing is subjected

=

=

=198.6x1250x(510-178)x10^-6=82.4KN

< ,

Since the difference between them is large increase the depth of footing

Try depth of footing =300mmEffective depth for bottom bars =

=300-54=246mm

Effective depth for top bars ==300-62=238mm

= . 1 1 .x380x246=368mm2Provide 9 Nos#8mm bars, area provided=450mm2

= . 1 1 .

x380x238=383mm2Check for one way shear for bending about y-axis:Critical section for one way shear about y-axis is taken at a distance fromthe face of the column.

Depth of footing above rectangular portion at critical section.

D1=y1-((-e)y1/x1)=(300-150)-((238-75)x150/435=94mmWidth of footing at critical sectionB2=D+2=230+2x238=706mmArea of footing at critical section==(706+1250)94/2+(150-62)x1250=201932mm2

Percentage of steel= =100x450/201932=0.222%,

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GNIT 54

=0.3376N/mm2Shear resisted by concrete=

=x=0.3376x201932/1000=68.17KNShear to concrete footing is subjected

= = =198.6x1250x(510-238)x10^-6=67.5KN >

,

Since the difference is small increasing the number of bars.

Provide10 Nos#8mm bars. Area provided=500mm2=100x500/201932=0.25%=0.36N/mm2Shear resisted by concrete =0.36x201932/1000=72.7>VI.check for one way shear for bending about x-axis:

Provide 9Nos#8mm bars.=450mm2, =300-8/2=246mm2D3=y1-((-e)y1/x1=150-(246-75)x150/435=91mmWidth at top of footing=B3=b+2=230+2x246=722mmArea of footing at critical section==(B3+Bf)D3/2+(Dfmin-dx)Bf=(22+1250)91/2+(150-54)x1250=209726mm2

Percentage of steel =100x450/209726=0.215%=0.332N/mm2Shear resisted by concrete =0.332x209726/1000=69.6KNShear to which footing is subjected

= =198.6x1250x(510-246)x10^-6=66KN

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GNIT 55

> Therefore, safe.

VII.check for bearing pressure at column base

< 0.451/2 where 1/2 |>2A1= or(b+4) (D+4) whichever is less=1250x1250 or (230+4x300=1562500mm2 or 2044900mm2

Therefore,1562500mm2

A2=bxD=230x230=52900mm2

12 = 5.4 > 2Therefore 1/2=2.Actual bearing pressure

=286x1000/(230x230)=5.4N/mm2Permissible bearing pressure=0.451/2=0.45x20x2=18N/mm2>5.4N/mm2Therefore,safe

VIII.RESULTS:

Size of footing =1250x1250

Total depth of footing = 300mm

Minimum depth of footing = 150mm

No. dia of bars along long direction=9#8

No. dia of bars along short direction =10#8

Clear distance between bars along long direction=133mm

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GNIT 56

Clear distance between bars along short direction=118mm

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GNIT 57

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GNIT 58

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GNIT 59

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References:

1. Illustrated design of reinforced concrete buildings by Dr.V.L.Shah and Dr.S.R.Karve

Code Books

1. IS 456-2000 for design of beams, columns and slabs.2. SP-16 for design of columns.

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