analysis and design of multistoried building

8/10/2019 Analysis and Design of Multistoried Building

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ANALYSIS AND DESIGN

OFMULTISTORIED BUILDING


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INTRODUCTION

Multi storied building is one which has more than

two or more apartments. It takes limited space forconstructing and solves the rental house problem.

Necessity:

1. Increase of population2. Scarcity of land &limited fund

3. Migration of population from villages to

Cities

4. Factors to be considered in the finalisation

of site &requirements.


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Specifications

Bed room - 3.0 m*3.6m.

Living room - 4.2*4.8m

Guest room - 3.0m*3.6m

Verandah - 1.8m*3.0m.

Office room - 3.0m*3.6m.


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Specifications

Dinning room - 3.6m*4.2m to4.2m*4.8m.

Kitchen - 2.5m*3.9m to3.0*3.0m.

Store room - 2.5m*2.5m to 3.0m*3.0m.

Bath&w.c - 1.8m*1.8m to1.8m*2.5m.


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Plan details

The plan consists of two bed rooms ,one

kitchen , one living room, bath & w.c

attached for two bed rooms. This issymmetrically placed on the four sides of

the building. Our multi storied building

consists of 6 stories. The ground floor isused for parking, power room, and

watchman`s room.


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ESTIMATION OF LOADS

The minimum requirements pertaining to thestructural safety of buildings are being covered

by way of laying down minimum design loads

which have to be assumed.

Various types of loads acting on the structure are

as follows:

1. Dead load2. Imposed load

3. Wind load

4. Seismic load


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DEAD LOAD

Dead load means the self weight of super

structure.

It can obtained by using preliminary design.

Preliminary design means checking for the

cross-sections for which we have assumed.

By using that dimensions we can compute thedead loads of the structure.

Dead load means including weight of the

beams, slabs, etc.


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IMPOSED LOAD

The load assumed to be produced by the

intended use or occupancy of a building,

including the weight of movable partitions ,distributed , concentrated loads, load due to

impact and vibration.

But these cannot include wind, seismic,snow and other loads due temperature

changes, creep etc.,.


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Imposed Loads for different

occupancies

Various values of imposed loads are:

All rooms and kitchens - 2.0 Kn/m2Toilets and bath rooms - 2.0

Corridors, staircase etc., - 3.0

Balconies - 3.0


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WIND LOAD

Wind is air in motion relative to the surface of

the earth.

The wind generally blows horizontal to theground at high wind speeds.

The wind speeds are assessed with the aid of

anemometers or anemographs.Very strong winds are generally associated

with cyclonic storms, thunderstorms etc.,


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Design of wind speed

Design wind speed (Vz)

Vz=Vb*k1*k2*k3where

Vb=design wind speed at any height z in m/s

k1=risk coefficientk2=structure size factor

k3=topography factor


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SEISMIC LOAD

The forces exerted on the structures due tomovement of acceleration of ground surfaces arecalled Earthquake forces.

This acceleration can be divided into vertical andhorizontal components.

Vertical acceleration can be neglected.

But the horizontal component can be severe andbuildings erected in seismic zone, should bedesigned on the basis of loads

For additional lateral loads which are equal to

some % of weight of the building.


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Force calculation

Design lateral force (Qi)

Qi=Vb* Wi*hi^2

i=1 to n Wi*hi^2

where Vb = Ah*w


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Design spectrum(Ah)= Z*I*Sa/(2*R*g)

Z = zone factor

I = Importance factor

Sa/g = acceleration response spectrum

R = Response reduction factor

w = seismic weight of building

Wi = seismic weight of floor Ihi = height of floor from base of building

n = no.of stories


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ANALYSIS

Analysis of the building means estimationof loads acting on the each component of the

building on each floor like beams, columns

etc.,

Using this analysis we can compute the

Bending Moments and Shear Forces acting

on the beams, columns, and slabs.

Using this values we can design the

individual components of the structure.


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DESIGN

Design Of Multistoried Building Consists of:

1. Design of Slabs

2. Design of Beams

3. Design of Columns

4. Design of Footings

5. Design of Stair-cases


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SLABS

DEFINITION:-Slabs are plate elements formingfloors and roofs of distributed loads primarily byflexure.

Slabs are classified according to the method ofsupport,

1.one-way slabs,

2.two-way slabs,3.flat slabs,

4.circular slabs,

5.grid floors and ribbed beams.


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BEAMS

A reinforced concrete beam should be able

to resist tensile, compressive and shear

stresses induced in it by the loads on them. Beams are furthur classified into,

1.Singly reinforced beams,

2.Doubly reinforced beams,

3.Flanged beams


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COLUMNS

A column may be defined as an element used primarily tosupport axial compressive loads with a height of at least

three times its least lateral dimension.

Columns are subjected to ,

Axial load,

Uni-axial bending moment,

Bi-axial bending moment.

Columns may be classified on the basis of slenderness

ratio,

1.Short columns,

2.Long columns.


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FOUNDATIONS DEFINITION:- The foundation of a structure is that part of

the structure which transfers the load to the soil on which itrests.

The ground on which the foundation rests is called the sub-grade or foundation soil.

Foundations may be broadly classified in to, Shallow foundations,

Deep foundations.

Shallow foundations are the common footings generally

adopted in cases of buildings,hospitals,schools buildings etc.

Isolated footings, combined footings, &wall footings are theexamples of Shallow foundations.

Pile foundations are the example of Deep foundations.


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STAIR-CASES

DEFINITION:-The purpose of a stair_case is to beprovided pedestrain access to different levels within a building.

There are two main components of a stair-case :Stairs and Landing slab.

Classification of stairs:-

1.Straight stairs,2.Dog-legged stairs,

3.Open newel stairs,

4.Geometrical stairs.

analysis and design of multistoried building

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