form house design

8/9/2019 Form House Design

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SSEEIISSMMIICCRREEGGIIOONN

SSEESSSSIIOONN22000033((FF))--22000077

Project Advisor:

ENGR. MUHAMMAD IRFAN-UL-HASSAN

( ASSISTANT PROFESSOR )

Submitted By:

SAFEER ABBAS 2003(F)-CIVIL-988MOHAMMAD AFZAL 2003(F)-CIVIL-982ADNAN KHALID 2003(F)-CIVIL-976MOHAMMAD AHSAN 2003(F)-CIVIL-987

Department Of Civil Engineering

University of Engineering & Technology

Lahore.


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DESIGN OF FARMHOUSE

IN

SEISMIC REGION

This project is submitted to Department of Civil Engineering,

University of Engineering and Technology, Lahore-Pakistan, for the partial

fulfillment of the requirement for the degree of

Bachelors of Science

InCIVIL ENGINEERING

Approved on: _______________

Internal examiner: Sign: ____________________________

(Project advisor) Name: Engr. Muhammad Irfan-ul-Hassan

External examiner: Sign: ____________________________

Name: ____________________________

Department of Civil EngineeringUniversity of Engineering and Technology

Lahore-Pakistan


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TTAABBLLEEOOFFCCOONNTTEENNTTSS

ARCHITECTURAL PLANS

CHAPTER 1: INTRODUCTION 1

1.1 Earthquake 1

1.2 Old concepts about an earthquake 2

1.3 Causes of Earthquake 2

1.4 Types of Earthquakes 3

1.5 Earthquake Measuring Instruments 3

1.6 How does Earthquake affect Building 4

1.7 Complexity of Earthquake Ground motion 6

1.8 Effects of Earthquakes 6

1.9 Earthquakes in Pakistan 9

1.10 Scope of Seismic design of structure 11

1.11 Objectives of Project 11

1.12 Introduction of Project 12

CHAPTER 2: LITERATURE REVIEW 13

2.1 Codes 13

2.1.1 ACI CODE

2.1.2 UBC 97

2.2 Masonry Design 24

2.3 Related Terms 27

2.3.1 Beam

2.3.3 Column

2.3.4 Slab

2.3.5 Wall & Footing


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2.4 Fundamental Assumptions for Reinforced Concrete 35

Behavior

2.5 Design Basis 35

2.6 Trend of making the earthquake resistant structures 36

2.6.1 Present Practices in Pakistan

CHAPTER 3: SEISMIC DESIGN OF STRUCTURE 38

3.1 Purpose 38

3.2 Minimum Seismic Design 38

3.3 Seismic and Wind Design 393.4 Some Related Terms 39

3.5 Construction Of Buildings In Seismic Region 43

3.5.1 Dead loads

3..5.2 Live loads

3.5.3 Dynamic / viberations loads

3.5.4 Wind loads

3.5.5 Seismic loads3.5.6 Thermal loads

3.5.7 Shrinkage and creep

3.5.8 Snow loads

3.6 Structural systems 50

3.7 Expansion and separation joints 51

3.8 Foundations and substructures 51

3.9 Method of analysis 523.10 For single to two storey houses units 52

3.10.1 Materials

3.10.2 Structural forms and building cconfigurations

3.10.3 Horizontal reinforcement in walls

3.10.4 Plinth Band


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3.10.5 Lintel Band

3.10.6 Roof Band

3.10.7 Vertical reinforcement in walls

3.10.8 Vertical joints between orthogonal walls

3.10.9 Dowels at corner and junctions

3.11 Guideline for multistory frame structure 57

3.11.1 Material types for wall

3.11.2 Foundations

3.11.3 Masonary shear walls

3.11.4 Reinforced concrete walls

3.11.5 Minimum beam , column and slab sizes

CHAPTER 4: DESIGN METHODOLOGY 59

4.1 Two-Way Slabs.

4.1.2 Design by the coefficient method

4.2 For One way slab 60

4.2.1 Design procedure

4.3 Beams 62

4.3.1 Design of structural beams

4.3.1.1 Design procedure for simply

Supported beams

4.3.1.2 Design procedure for doubly

reinforced beams

4.3.1.3 Design procedure for continuous

Beam

4.4 Design of lintels 65

4.4.1 Wall load on lintel

4.5 Columns 66

4.5.1 Design procedure for the


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Structural columns

4.6 Wall design and foundations 67

4.6.1 Design of masonary foundation

4.6.2 Thickness of wall

4.6.3 Design procedure for isolated footing

4.7 Design of stairs 69

4.8 Software used in design of

farm house as frame structure 69

4.8.1 Overview of ETABS program

4.8.2 Procedure for modeling in ETABS

STRUCTURAL PLANS

CHAPTER 5: DESIGN OF FARMHOUSE 76

A ) Manual Calculations

5.1 Walls And Foundations 77

5.1.1 Exterior wall ( W1 )


5.1.3 Interior wall ( W2 )

5.1.4 Interior wall ( W2 )


5.1.6 Conclusions

5.2 Design of column ( C3 ) footing 84

5.3 Design of column ( C2 ) footing 90

5.4 Design of slabs 96

5.4.1 Design of ground floor slab system

5.4.2 Design of first floor slab system

5.5 Design of beams 110

5.5.1 Non structural beams


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5.5.2 Structural beams

5.6 Design of lintels 115

5.7 Design of columns 118

5.8 Design of stairs 124

B ) Computer aided asnalysis and results 127

Drawings

CONCLUSIONS & RECOMMENDATIONS 156

REFERENCES


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1

IINNTTRROODDUUCCTTIIOONN

No natural event is more frightening than an earthquake

because earthquake strikes (damages) suddenly without giving any warning. The frame

and huge foundation of the earth shake like a coward. The destructive movements are all

over in less than a minute, leaving behind fallen dreams and broken structures.

Earthquake , like other natural disasters, have affected hundreds of thousands of persons

directly over the ages. Earthquake is a major problem for mankind, killing thousands

each year. Earthquake are causing death and destruction in a wide variety of ways, from

building collapse to conflagrations , tsunamis , landslides. In Pakistan earthquakes are not

so common compared to other part of the world but some areas of Pakistan (North and

South Himalayas) lies in the area of high seismic zone. Recently 8th

October 2005

earthquake shakes the most part of Azad Kashmir and NWFP and causes huge

destruction and loss of life.

C H A P T E R

1


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CHAPTER 1 Introduction

2

1 . 1 EARTHQUAKE

An earthquake is a disturbance or vibration of earth by different types of natural and

human induced phenomenon e.g. meteoric impact, volcanic activity, under ground

nuclear explosion, rock stress changes due to large reservoirs, and movements of tectonic

plates. During an earthquake the earth's surface starts vibrating, and rumbling and roaring

noise come from underneath and the buildings start cracking and collapsing, and the

people get frightening.

1 . 2 OLD CONCEPTS ABOUT AN EARTHQUAKE

Mythological explanations for earthquakes have included the ox who carries the earth on

one shoulder [or in some versions, one horn] and causes earthquakes when shifting the

earth to the other shoulder or horn. According to some accounts, Pythagoras suggested

that earthquakes resulted from the multitudes of dead people fighting under the earth.

1 . 3 CAUSES OF EARTHQUAKE

The sudden slip that is an earthquake results from a gradual build-up of stress inside the

earth. Basically, the rocks that make up the outer layers of the Earth, if subjected to

sufficient force, can be brought to a "breaking point". It is even easier for them to snap if

certain places are already weakened, much the way a sheet of paper will tear more readily

along a sharp crease. When the stress in a particular location is great enough to overcome

the forces holding together the rocks below us, something, effectively, "breaks" or "gives

way", and an earthquake begins. The forces needed to cause this stress and move such

large masses of rock are immense.


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3

Tectonics deals with structural ruptures at the plate boundaries. These plates drift very

slowly with relation to each other as they "float" on the more fluid material (the mantle)

beneath them. At their edges, they may be colliding, separating, or moving laterally past

each other. The nature of these plate to plate boundaries has a tremendous effect on the

geology, volcanic and seismic activity along the edges of each plate.Earthquakes are

therefore the result of tectonic movements. The crust of the earth consists of several very

thick plates, and at the boundaries of these plates as well as within each plate

geological discontinuities, known as faults, usually occur. The sudden relative movement

of plates at a fault engenders vertical and horizontal vibrations of the ground over a large

area, usually causing damage to structures and also loss of life.

Therefore earthquakes are the result of tectonic movements, Meteoric impact , Volcanic

activity, Under Ground nuclear explosions , Rock stresses change due to large reservoirs

1 . 4 TYPES OF EARTHQUAKES

1 )Tectonic earthquakes

2 )Interplate earthquakes

3 )Deep focus earthquakes

4 )Volcanoes

1 . 5 EARTHQUAKE MEASURING INSTRUMENTS

There are different types of earthquakes measuring instruments e.g. accelerograph,

seismograph but the principle of working of these are almost same.These instruments are

used to measure ground shaking and structural vibration during an earthquake. The basic

element of vibration measuring instrument is a transducer.Three separate transducers are
http://www.answers.com/topic/interplate-earthquakehttp://www.answers.com/topic/deep-focus-earthquakehttp://www.answers.com/topic/deep-focus-earthquakehttp://www.answers.com/topic/volcanohttp://www.answers.com/topic/volcanohttp://www.answers.com/topic/deep-focus-earthquakehttp://www.answers.com/topic/interplate-earthquake


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4

required to measure the three components of motion i.e. two horizontal and one vertical.

The data can be obtained in the form of three acceleration components.

SEISMOGRAPH

SEISMOGRAM

Figure 1.1 Seismograph Figure 1.2 Seismogram

1 . 6 HOW DO EARTHQUAKES AFFECT BUILDINGS

The dynamic response of the building to earthquake ground motion is the most important

cause of earthquake-induced damage to buildings. Failure of the ground and soil beneath

buildings is also a major cause of damage. Most earthquakes result from rapid movement

along the plane of faults within the earth's crust. This sudden movement of the fault

releases a great deal of energy, which then travels through the earth in the form of

seismic waves.


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5

Figure 1.3showing the movement of seismic waves

The seismic waves travel for great distances before finally losing their energy.At some

time after their generation, these seismic waves will reach the earth's surface,and set it in

motion, which we not surprisingly refer to as earthquake ground motion. When this

earthquake ground motion occurs beneath a building and when it is strong enough, it sets

the building in motion, starting with the foundation, and transfers the motion throughout

the rest of the building in a very complex way. These motions in turn induce forces which

can produce damage. Ground motion at a building site is vastly more complicated than

the wave form. Compare the surface of the ground in an earthquake to the surface of a

small body of water. You can set the surface of a pond in motion--by throwing stones

into it. The firstfew stones create a series of circular waves, which soon begin to collide

with one another. After a while, interferencepatterns begin to predominate and the

originalwaves disappear. In an earthquake, the ground vibrates in a similar manner, as

waves of different frequencies and amplitude interact with one another


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6

1 . 7 COMPLEXITY OF EARTHQUAKE GROUND MOTION

The complexity of earthquake ground motion is due to three factors:

1)SOURCE EFFECTS

The seismic waves generated at the time of earthquake fault movement are not all

uniform.

2)PATH EFFECTS

As seismic waves pass through the earth on their way from the fault to the building

site, they are modified by the soil and rock media through which they pass.

3)LOCAL SITE EFFECTS

Once the seismic waves reach the building site they undergo further modifications,

which are dependent upon the characteristics of the ground and soil beneath the building

1 . 8 EFFECTS OF EARTHQUAKES

There are many effects of earthquakes, these include, but are not limited to,

1 )Broken windows

2 )Collapse of buildings

3 )Fires

4 )Landslides

5 )Destabilizations of the base of some buildings which may lead to collapse in a

future earthquake

6 )Disease

7 )Lack of basic necessities

8 )Human loss of life


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7

9 )Higher insurance premiums

+

Figure 1.4shows the broken windows Figure 1.5shows that the whole building tilted( Turkey ) on left side after the earthquake.

Figure 1.6shows that the building collapses Figure 1.7earthquake in Ahmedabadduring an earthquake in (26-01-2001)

Ahmedabad (27-01-2001)

Fault rupture tearing apart a building in Glck Naval Base


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8

Figure 1.8shows that the building get inserted into the ground and tilted due to earthquake. ( Bhug )


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9

1 . 9 EARTHQUAKES IN PAKISTAN

Major Earthquakes in Pakistan are,

Year Location

1935 Quetta (Balochistan)

1945 Makran coast (Baluchistan)

1974 NE of Malakhand, NWFP

1981 Gilgit Wazarat (Jammu & Kashmir)

1997 Near Harnai (Baluchistan),

2001 Near Bhachau (Gujarat )

2002 Gilgit

2005 Ballakot , Muzzafarabd , Kashmir

Figure 1.9 (Margala tower ) Figure 1.10(Margala tower )


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10

Figure 1.11 ( Muzzaffarabad)

Figure 1.12 ( Muzzaffarabad ) Figure 1.13 ( Muzzaffarabad)


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11

1 . 10 SCOPE OF SEISMIC DESIGN OF STRUCTURE

After 8th

October earthquake in Pakistan the importance of earthquake resistant structures

have increased. Now a day the scope of Seismic design of structures is increase because

peoples are more interested to construct earthquake resisting structures for their domestic

and commercial activity. Even if our structure is going to built at a site where there is a

minimum chances of earthquake, we have to consider the earthquake forces and then

design accordingly.

1 . 11 OBJECTIVES OF PROJECT

In this project ( DESIGN OF FARM HOUSE IN SEISMIC REGION ) the main objective is to

understand the whole design process of design practice , to under stand the special

provisions that are made to make the structure earth quake resistant according to the

seismic codes ( UBC 97 ).

In common study practice usually design of individual structural components is carried

out. The main purpose behind the project is to design the whole building by applying the

seismic provisions when only architectural drawings are given, while the engineer has to

determine the all the input data himself as many design parameters are required at

different design stages.

To understand the masonry construction of the houses in the seismic region is also the

one of the objective in this project. The objective is to get the knowledge of the different

techniques that are used in the masonry construction of the houses in the seismic regions.


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12

The aim is to understand, what separate things (materials) that are used in the

construction of masonry wall in the seismic region.

The objective of this project is also to understand the Computer Aided analysis and

Design of the structures. The aim is to understand how seismic loads are applied on the

structures in the computer software.

1 . 12 INTRODUCTION TO THE PROJECT

In this project (design of farm house in seismic region) we have design the walls,

foundations, slab systems, beams, lintels and columns of the farm house. Some special

measures are adopted to make this masonry building as earthquake resistant.

In our project, first we manually design the structural components of the load bearing

farm house with some extra seismic provisions and then we convert our farm house in a

frame structure and then whole design is carried out through ETABS.

In chapter 2 of this project, we discuss the codes & related articles from the different

books. Seismic provisions and their implementation for the structures have been

discussed in 3rd

chapter. Design methodologies are in chapter 4 and manual calculations

& computer aided results are done in chapter 5.

Different self made excel sheets are prepared for the design of different structural

components (beams, slabs, lintels).


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LLIITTEERRAATTUURREERREEVVIIEEWW

C H A P T E R

2The code covers the design of structural concrete used in buildings and where

applicable in structures. ACI 318-05 was adopted as a standard of the American

Concrete Institute October 27, 2004 to supersede ACI 318-02 in accordance with the

Institutes standardization procedure.UBC-97 (Uniform building Code) is adopted for

the seismic design of structures.

22..11 CCOODDEESS

22..11..11 AACCII 331188--0055

ACI 7.6.1

The minimum clear spacing between parallel bars in a layer shall be dbbut not less than

25mm.

ACI 7.6.2

Where parallel reinforcement is placed in two or more layers, bars in upper layers shall be

placed directly above bars in the bottom layers with clear distance between layers not less

than 25mm.

ACI 7.6.3

In spirally reinforced or tied reinforced compression members, clear distance between

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CHAPTER 2 literature review

longitudinal bars all not be less than 1.5dbor 40mm.

ACI 7.6.5

In walls and slabs other than concrete joist Construction, primary flexural reinforcement

shall be spaced not farther than three times the wall thickness, nor 450mm.

ACI 7.10.5.2

Vertical Spacing of ties shall not exceed 16 longitudinal bar diameters, 48 tie diameter or

lest dimension of compression member.

ACI 7.12.1

Reinforcement for shrinkage and temperature stresses normal to flexural reinforcement shall

be provided in structural slabs where the flexural reinforcement extends in one direction

only.

ACI 7.12.2.1

Area of shrinkage and temperature reinforcement shall provide at least the following ratios

of reinforcement area to the gross area, but not less than 0.0014,

a) Slabs where grade 40 or 50 deformed bars are used 0.0020b) Slabs where grade 60 deformed bars are used 0.0018

ACI 7.12.2.2

Shrinkage and temperature reinforcement shall be placed not farther apart than five times

the slab thickness, nor farther apart than 450mm.

ACI 9.5.2.1

Minimum thickness in Table 9.5(a) shall apply for one-way construction not supporting or

attached to partitions or other construction likely to be damaged by large deflections, unless

computation of deflection can be used without adverse effects.

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ACI 9.5 (a) MINIMUM THICKNESS OF NON-PRESTRESSED BEAMS ORONE-WAY SLABS

Minimum thickness, h,

Simply SupportedOne End

Continuous

Both Ends

ContinuousCantilever

Members

Construction

Members not supporting or attached to partitions or other likely to be damaged by

large deflections.

Solid One-Way

Slabs1/20 1/24 1/28 1/10

Beams Or RibbedOne-Way Slabs

1/16 1/18.5 1/21 1/8

Table 2.1

ACI 9.3.2

Strength reduction factor shall as follows,

Tension controlled section 0.9Compression controlled section 0.65

ACI 9.3.2.3

Shear and torsion 0.75

ACI 10.2.2

Strain in the reinforcement and concrete shall be assumed directly proportional to the

distance from the neutral axis.

ACI 10.2.3

Maximum usable strain at the extreme concrete compression fiber shall be assumed equal to

0.003.

ACI 10.2.5

Tensile strength of concrete shall be neglected in axial and flexural calculations of

reinforced concrete.

ACI 10.3.6

Design axial load strength Pnof the compression member shall not be taken greater than

the following:

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ACI 10.3.6.1

For non pre-stressed members with spiral reinforcement conforming to 7.10.4 or composite

members conforming to 10.14

Pn= 0.85[0.85fc'(Ag Ast) + fyAst]

ACI 10.3.6.2

For non pre-stressed members with tie reinforcement conforming to 7.10.5

Pn= 0.85[0.85fc'(Ag Ast) + fyAst]

ACI 10.5.4

For structural slabs of uniform thickness, minimum area and maximum spacing of

reinforcement in the direction of the span shall be as required for shrinkage and temperature

according to 7.12.

ACI 10.9.1

Area of longitudinal reinforcement for non composite compression members shall

not be less than 0.01 or more than 0.08 time's gross area Ag of the section .

ACI 10.9.2

Minimum number of longitudinal bars in compression members shall be 4 for bars

within rectangular ties or circular ties, 3 for bars within triangular ties.

ACI 11.5.5.1

Spacing of shear reinforcement placed perpendicular to the axis of the member shall

not exceed d/2 in non pre-stressed member.

CI 11.5.5.2

Inclined stirrups and bent longitudinal reinforcement shall be so spaced that every

45o line, extending toward the reaction from mid depth of member d/2 to longitudinal

tension reinforcement, shall be crossed by at least one line of shear reinforcement.

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ACI 11.5.7.1

When factored shear force Vuexceeds shear strength Vcshear reinforcement shall

be provided to satisfy eqs 11-1 & 11-2.

ACI 15.2.2

Base area of footing shall be determined from un-factored forces and moments

transmitted by footing to soil and permissible soil pressure selected through principles of

soil mechanics.

ACI 15.4.1

External moments on any section of a footing shall be determined by passing a

vertical plane through the footing, and computing the moment of the forces acting over

entire area of the footing on one side in that vertical plane.

ACI 15.4.2

Maximum factored moment for an isolated footing shall be computed as prescribed

in 15.4.1 at critical sections located as follows:

a) At the face of column, pedestal, or wall, for footings supporting a concrete column,

pedestal or wall.

b) Halfway between middle and edge of wall, for footings supporting a masonry wall.

ACI 15.4.3

In one-way footings, and two-way square footings, reinforcement shall be distributed

uniformly across entire width of footing.

ACI 15.4.4

In two-way rectangular footings, reinforcement shall be distributed as follows:

ACI 15.4.4.1

Reinforcement in long direction shall be distributed uniformly across entire width of

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the footing.

ACI 15.4.4.2

For reinforcement in short direction in a rectangular footing a portion of the total

reinforcement given by Eq.15-1 shall be distributed uniformly over a bandwidth equal to the

length of short side of the footing. Remainder of reinforcement required in short direction

shall be distributed uniformly outside centre bandwidth of the footing.

REINFORCEMENT IN BAND WIDTH = 2

TOTAL REINFORCEMENT IN SHORT DIRECTION + 1

ACI 15.5.1

Shear strength of footings shall be in accordance with 11.12.

ACI 15.8.1

Forces and moments at base of the columns, wall, or pedestal shall be transferred to

supporting pedestal or footing by bearing on concrete and by reinforcement dowels and

mechanical connectors.

ACI 15.8.2

In cast in-situ construction, reinforcement required to satisfy 15.8.1. shall be

provided either by extending longitudinal bars into supporting pedestal, footing or by

dowels.

ACI 15.8.2.1

For cast in place columns area of reinforcement across interface shall be not less

than 0.005 times gross area of supported member.

ACI 15.7

Depth of footing above bottom reinforcement shall not be less than 150mm, for

footings on soil .

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ACI 15.6.3

Critical sections for development of reinforcement shall be assumed at the same

location as defined in 15.4.2 for maximum factored moment.

ACI 21.2.1.4

In regions of high seismic risks or for structures assigned to high seismic

performance special moment frames special structural walls shall be used resists forces

induced by earthquake motion.

ACI 21.2.3

Strength reduction factor shall be as given in 9.3.4

ACI 21.2.4.1

Specified compressive strength of concrete shall not be less than 3000 Psi

ACI 21.3.1.1

Factored axial compressive force on the member, Pu shall not exceed Agfc' / 10

ACI 21.3.1.2

Clear spans for flexural members, ln shall not be less than four times its effective depth.

ACI 21.3.1.3

Width of flexural member, bw , shall not be less than the smaller of 0.3h & 250mm.

ACI 21.3.1.4

Width of flexural member, bw , shall not exceed the width of the supporting member plus

distance on each side of supporting member not exceeding three fourth of the depth the

flexural member.

ACI 21.3.2.1

At any section of flexural member for top as well as for bottom reinforcement, the amount

of reinforcement shall not be less than eq 10.3 and the reinforcement ratio shall not exceed

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0.025.Atleast 2 bars shall be provided continuously both top and bottom.

ACI 21.3.2.2

Positive moment strength at joint face shall not be less than one half of the negative moment

strength provided at back face of joint.

ACI 21.4.1.1

The shortest cross sectional dimension measured on a straight line passing through the

geometric centroid shall not be less than 300mm

ACI 21.4.3.1

Area of longitudinal reinforcement shall not be less than 0.01Ag or more than 0.06Ag.

ACI MOMENTS COEFFICIENT

o Positive moment End spans

Discontinuous end unrestrained............................... wuln2/11

Discontinuous end integral with support ...................... wuln2/14

Interior spans .................................................................wuln2/16

o Negative moments at exterior face of first interior support

Two spans ......................................... wuln2

/9

More than two spans...................... wuln2/10

o Negative moment at other faces of interior supports............. wuln2/11

o Negative moment at face of all supports for Slabs with spans not exceeding 10 ft;

and beams where ratio of sum of column stiffness to beam stiffness exceeds eight

at each end of the span.. wuln2/12

o of exterior support for members built integrally with supports

Where support is spandrel beam ... wuln2

/24

Where support is a column .............. .wuln2/16

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ACI 3 . 2 CEMENT

ACI 3 . 2.1 Cement shall conform to one of the following specifications:

(a)Specification for Portland Cement (ASTM C 150)

(b)Specification for Blended Hydraulic Cements (ASTM C 595), excluding Types S

and SA which are not intended as principal cementing constituents of structural

concrete.

(c)Specification for Expansive Hydraulic Cement (ASTM C 845)

(d)Performance Specification for Hydraulic Cement (ASTM C 1157)

ACI 3 . 3 AGGREGATE

ACI 3 . 3.1 Concrete aggregates shall conform to one of the following specifications:

(a)Specification for Concrete Aggregates (ASTM C 33)

(b)Specification for Lightweight Aggregates for Structural Concrete (ASTM C 330)

ACI 3 . 3.2 Nominal maximum size of coarse aggregate shall be not larger than:(a)1/5 the narrowest dimension between sides of forms, nor

(b)1/3 the depth of slabs, nor

(c)3/4 the minimum clear spacing between individual reinforcing bars or

wires, bundles of bars.

ACI 3 . 4 WATER

ACI 3 . 4.1 Water used in mixing concrete shall be clean and free from injurious

amounts of oils, acids, alkalis, salts, organic materials, or other substances

deleterious to concrete or reinforcement.

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22..11..22 UUBBCC9977

22..11..22..11

BBAASSEESSHHEEAARR

According to UBC 97 1630.2.1

V = CVI x W

RT

W = Total weight of structure.

V = Design base shear at the base of structure.

Cv = Seismic coefficient based on acceleration& dependent on

soil condition & seismicity of the region

I = Seismic Importance Factor

= Its value is 1 , 1.25 , 1.5 for ordinary structure , Special & Essential structure .

R = Structural coefficient depending upon ductility and overstrength of the structure

T = Fundamental Time Period of the Structure.

Ta = Ct (hn ) 3/4

Where

Ta = Approx. time period

Ct = 0.035 for steel structure

= 0 .03 for concrete structure

= 0 .02 for other structures

hn = Total height of structure.

TB= Tme period obtained by analysis

Max. value of V is = 2.5 Ca I x WR

W = It include the dead load plus the partition load &floor finishes& cladding

In case of storage building 25% of the live load can be considered

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In case of snow load 20% of the flat roof snow load can be considered.

If flat snow load > 30 lb/ft^2

P.L = 10lb/ft^2 = F.F = cladding

Vmin = 0. 11Ca I W

Ca = similar to Cv

= Constant Value of Ca Cv can be read from table.

For seismic zone :

V = 0.8 Z Nv I x W

R

Z = seismic coefficient = 0.4 for zone 4

(Balakot, Muzaffarbad, Bagh, Quetta, Chamman, Gilgit, Malakand)

Z = 0.3 for zone 3

( Rawalpindi , Islamabad , Peshawar )

Z = 0.2 for zone 2B

(Lahore Faisalbad, Jhang)

Z = 0.15 for zone 2A

Z = 0. 075 for zone 1

(Multan, D.G Khan, Bahawalpur )

Nv, Na = near source factor for zone 4 & in conjunction with soil type

VERTICAL DISTRIBUTION OF FORCES

According to UBC 97 1630.5

Fx = ( P Ft ) Wxhxwihi

Where

Fx = Story lateral force

V = Total base shear

Ft = Additional force at the top for the participation & higher mode in the large structures.

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Ft = 0.07 T V [0. 25 V IF T > 0.07 sec

Ft = 0 if T [0. 7sec.

Wx = Storey load

Hx = Storey height

Storey Shear is ,

Vx = Ft + Fi

DRIFT RATIO / DRIFT LIMITATION / ALLOWABLE STOREY

LATERAL DEFLECTION

According to UBC 97 1630.9.2

M = 0.7 R s

Where ,

M = Max. Deflection/max.inelastic response/max. inelastic deflection.

s = Horizontal Deflection at mid height under Factored Load

R = A constant

2 . 1.2.2 MASONARY DESIGN

SLENDERNESS RATIO

R = H or l = 18

t t

For load bearing wall = 20

= 18 for non-loading bearing in case of exterior walls.

= 36 for interior wall ( non load bearing wall )

( See UBC table 21- O )

Where R = slenderness Ratio

H = Effective Storey Height

l = Length of wall

t = Thickness of wall

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ALLOWABLE COMRESSIVE STRESS ( UBC-97 2107.3.3)

The allowable compressive stress Fb is given by

Fb = 0.33 f 'm 13.8 Mpa

ALLOWABLE AXIAL COMPRESSIVE STRESS ( UBC-97 2107.3.2)

The allowable axial compressive stress Fa is given by

Fa = 0.25f 'm[1- (R/40)2] , R 29

Fa = 0.25f 'm[20/R]2 , R > 29 , R= slenderness Ratio

COMBINED AXIAL & COMPRESSIVE STRESS ( UBC-97 2107.3.4)

fa / Fa+ fb / Fb1.0

fa , fb = applied stresses

Fa, Fb = allowable strength

ALLOWABLE TENSILE STRENGTH ( UBC-97 2107.3.5)

The allowable tensile strength Ftis given by

Ft = 1 fm1/2

for tension perpendicular to bed joint7

Ft = 1 fm1/2 for tension perpendicular to head joint

15

Wherefm= compressive stress due to dead load only

ALLOWABLE SHEAR STRENGTH ( UBC-97 2107.3.6)

The allowable shear strength Fv is given by

Fv = 1 fm1/2

345 Kpa

1 2

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ALLOWABLE BEARING STRESS ( UBC-97 2107.3.8)

The allowable bearing stressFbris given by

Fbr = 0.26fm when full area is loaded

F'br= 0.38 f'm when 1/3rd or less area is loaded.

TTAABBLLEEUUBBCC1199--II--CCFFOOUUNNDDAATTIIOONNSSFFOORRBBEEAARRIINNGGWWAALLLLSS

WIDTH OF

FOOTING(inches)

THICKNESS OF

FOOTING(inches)

DEPTH BELOW

UNDISTURBED

GROUND

SURFACE(inches)

NUMBER OF

FLOORS

SUPPORTED BY THE

FOUNDATION X 25.4 for mm

12

3

1215

18

67

8

1218

24

TTAABBLLEE22..22

BEAM DETAILS

According to UBC 1921.3.1 , 1921.3.2 , 1921.5.4

COLUMN DETAILS

According to UBC 1921.4 , 1921.4.3 , 1921.4.4.4 , 1921.4.4.6 , 1921.4.4.2.

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2 . 3 RELATED TERMS

2 . 3.1 BEAM

Beam are the structural member that is subjected to a transverse loading and resists

the bending moments.

When a beam is subjected to bending moments, bending strains are produced. These strains

produce stresses in the beam, compression in the top and tension in the bottom. Bending

members must, therefore, be able to resist both tensile and compressive stresses.By

embedding reinforcement in the tension zone, we create a reinforced concrete member. Such

members can resist bending sufficiently.

TYPES OF CROSS SECTIONS W.R.T. FLEXURE AT ULTIMATE LOAD

LEVEL

1. TENSION CONTROLLED SECTION

A section in which the net tensile strain in the extreme tension steel is greater than or

equal to 0.005 when the corresponding concrete strain at the compression face is 0.003.

2. TRANSITION SECTION

The section in which net tensile strain in the extreme tension steel is greater than y

but less than 0.005 when corresponding concrete strain is 0.003.

3. COMPRESSION CONTROLLED SECTION

The section in which net steel strain in the extreme tension steel is lesser than y

when corresponding concrete strain is 0.003.

PRACTICAL CONSIDERATIONS

A ) COVER

Concrete cover is provided to protect steel against fire and corrosion and to improve

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bond strength. It reduces the wear of steel and attack of chemicals especially in

factories.

B ). SELECTION OF STEEL BARS

1 )When different diameters are selected the maximum difference can be a gap of

one size.

2 )Minimum number of bars must be at least two, one in each corner.

3 )Always Place the steel symmetrically.

4 )Preferably steel may be placed in a single layer but it is allowed to use 2 to 3

layers.

5 )Selected sizes should be easily available in market

6 )Small diameter (as far as possible) bars are easy to cut and bend and place.

C ) SPACING BETWEEN STEEL BARS

Minimum spacing must be lesser of the following

1 )Nominal diameter of bars

2 )25mm in beams & 40mm in columns

3)1.33 times the maximum size of aggregate used.

We can also give an additional margin of 5 mm.

- A minimum clear gap of 25 mm is to be provided between different layers of steel

- The spacing between bars must not exceed a maximum value for crack control

CONCRETE

Mixture of Portland cement or any other hydraulic cement, fine aggregate,

coarseaggregate, and water, with or without admixtures.

DEFORMED REINFORCEMENT

Deformed reinforcement is defined as that meeting the deformed reinforcement

specifications of 3.5.3.1, or the specifications of 3.5.3.3, 3.5.3.4, 3.5.3.5, or 3.5.3.6. No

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other reinforcement qualifies. This definition permits accurate statement of anchorage

lengths. Bars or wire not meeting the deformation requirements or welded wire

reinforcement not meeting the spacing requirements are plain reinforcement, for code

purposes, and may be used only for spirals.

CONTRACTION JOINT

Formed, sawed, or tooled groove in a concrete structure to create a weakened plane

and regulate the location of cracking resulting from the dimensional change of

different parts of the structure.

DEVELOPMENT LENGTH

Length of embedded reinforcement, including pretension strand, required to develop

the design strength of reinforcement at a critical section. ( See 9.3.3.)

EFFECTIVE DEPTH OF SECTION

Distance measured from extreme compression fiber to centroid of longitudinal tension

reinforcement.

EMBEDMENT LENGTH

Length of embedded reinforcement provided beyond a critical section.

MODULUS OF ELASTICITY

Ratio of normal stress to corresponding strain for tensile or compressive stresses below

proportional limit of material. ( See 8.5.)

MOMENT FRAME

Frame in which members and joints resist forces through flexure, shear, and axial

force.

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SPIRAL REINFORCEMENT

Continuously wound reinforcement in the form of a cylindrical helix.

STIRRUP

Reinforcement used to resist shear and torsion stresses in a structural member;

typically bars, wires, or welded wire reinforcement either single leg or bent into L, U,

or rectangular shapes and located perpendicular to or at an angle to longitudinal

reinforcement.

STRENGTH DESIGN

Nominal strength multiplied by a strength reduction factor . ( See 9.3.)

STRENGTH, NOMINAL

Strength of a member or cross section calculated in accordance with provisions and

assumptions of the strength design method of this code before application of any

strength reduction factors. ( See 9.3.1.).The basic requirement for strength design may

be expressed as follows:

Design strength Required strength

PnPu, MnMu,, VnVu

STRUCTURAL WALLS

Walls proportioned to resist combinations of shears, moments, and axial forces

induced by earthquake motions.

TIE

Loop of reinforcing bar or wire enclosing longitudinal reinforcement. A continuously

wound bar or wire in the form of a circle, rectangle, or other polygon shape without re-

entrant corners is acceptable.

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YIELD STRENGTH

Specified minimum yield strength or yield point of reinforcement. Yield strength or

yield point shall be determined in tension according to applicable ASTM standards

as modified by 3.5 of ACI code.

2 . 3.3 COLUMN

They are classified as concentrically loaded and eccentrically loaded

columns, depending on their configuration of the structural frame and the loading to which

they are subjected.

2 . 3.4 SLAB

A reinforced slab is a broad, flat plate, usually horizontal, with top and bottom surfaces

parallel or nearly so.

It may be supported by reinforced concrete beams (and is usually cast monolithically with

such beams), by masonry or by reinforced concrete walls, by steel structural members,

directly by columns, or continuously by ground.

ONE-WAY SLAB

The slab which resists the entire/major part of applied load by bending only in one

direction

5.0..

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and

L = c/c distance between supports.

BAR SPACING FOR SLABS

smaxwill be lesser of following.

1.) 3 x h (local practice is 2 x h) , for one way slabs

2.) 450 mm (local practice is 300 mm)

3.) (158300/fy) -2.5Cc

4.) 12600/fy

Where , Cc= Clear Cover

DISTRIBUTION, TEMPERATURE & SHRINKAGE STEEL FOR SLABS

Shrinkage and temperature reinforcement is required at right angle to main reinforcement to

minimize cracking and to tie the structure together to ensure its acting as assumed in design.

For Grade 300 0.2% of b x h= 0.002 As= 0.002bh

For Grade 420 0.18% of b x h = 0.0018 ..As= 0.0018bh

Smax. will be lesser of following

1 - 5 x h (field practice is 2 x h)

2 - 450 mm (field practice is 2 x h)

TWO-WAY SLAB

Slab resting on walls or sufficiently deep and rigid beams on all sides. Other

options are column supported slab e.g. Flat slab, waffle slab.

Two way slabs have two way bending.

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DESIGN METHODS

1 ).ACI co-efficient method

2 ).Direct design method

3 ).Equivalent frame method

4 ).Finite element method

MINIMUM DEPTH OF 2-WAY SLAB FOR DEFLECTION CONTROL

According to ACI-318-1963

hmin= (inner perimeter of slab panel)/180

90 mm

For fy= 300 MPa

180

LL2h

yx

min

+=

For fy= 420 Mpa

165

LL2h

yx

min

+=

According to ACI-318-2005

( )( )9m36

1500f8.0Lh

yn

min+

+=

y

x

L

Lm=

Ln = clear span in short direction

2 . 3.5 WALLS & FOOTINGS

FOUNDATION

Footings are structural members used to support columns and walls and to

transmit and distribute their loads to the soil in such a ay that the load bearing capacity of

the soil is not exceeded. Excessive settlement, differential settlement or rotations are

prevented and adequate safety against overturning or sliding is maintained

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TYPES OF FOOTINGS

Wall Footings

Isolated Footings

Combined Footings

Cantilever or Strap Footings Continuous Footings Raft or Mat Footing Pile Caps

DESIGN OF MASONARY FOUNDATION

Load is distributed at 60 degree in case of bricks & 45 degree in case of plain concrete

( a ) If the width of footing is not sufficient to accommodate the 60 degree load

distribution it will be un safe

( b ) If the width of footing is sufficient to accommodate 60 degree load distribution

which is safe but may be uneconomical

ASSUMPTIONS

1 )Load at the bottom of footing is uniformly distributed with out considering any voids

underneath the foundation.

2 )That voids may be present due to the uneven surface or uneven compaction3 )The effect of intersections is also ignored which are from perpendicular wall

4 )In case of boundary wall (property line wall) the resultant of soil pressure not coincide

with line of action of applied force that may result in over turning moment. In order to

avoid this footing is designed considering increased load by 35%.

5 )Effect of beam is also ignored.

6 )F.O.S for the bearing capacity is taken as 3 & for the backfill is 1.5.

STRENGTH OF BRICKS

Crushing strength of bricks ranges from 4.3 to 19.3 Mpa

Strength of first class brick in Punjab is 10.5 Mpa.

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25% of the strength is reduced in case of saturated condition Also more strength is

shown by machine due to the end plates effect so normally design strength is taken

half of the strength obtained by compression testing of bricks in dry condition.

So design strength =10.5 / 2 = 5.25 Mpa.

Available design strength is 70% in case of (1:3) c/s mortar.

It is 65% in case of (1:4) c/s mortar.

It is 45% in case of (1:6) c/s mortar

It is 30% in case of (mud) mortar.

Table 2.3

Mortar Compressive strength of brick1:3 4 MPa

1:4 3.4 MPa

1:6 2.4 Mpa

MUD 1.6 Mpa

STOREY HEIGHT

Storey height can be defined as the distance between plinth level & first

lateral support (as slab)

EFFECTIVE STOREY HEIGHT (H)

( 1 ) If lateral support + superimposed compressive load then

H = 0.75 x Storey height

( 2 )No lateral support + superimposed compressive load

H = 1.05 x storey height

( 3 ) No lateral support + no superimposed compressive load

H = 2 x Storey height

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22.. 4 FUNDAMENTAL ASSUMPTIONS FOR REINFORCED CONCRETE

BEHAVIOUR

The fundamental propositions on which the mechanics of reinforced concrete is

based are as follows:

The internal forces, such as bending moments, shear forces and normal, shear

stresses at any section of a member are in equilibrium with the effects of the

external loads at that section.

It is assumed that perfect bonding exists between concrete and steel at

the interface so that no slip can occur between the two materials. Hence, as the

one deforms, so must the other.

t is assumed that concrete is not capable of resisting any tension stress whatever.

2 . 5 DESIGN BASIS

The single most important characteristic of any structural member is its actual

strength, which must be large enough to resist, with some margin to spare, all

foreseeable loads that may act on it during the life of the structure, without failure or

other distress. It is logical, therefore, to proportion members, i.e., to select concrete

dimensions and reinforcement, so that member strengths are adequate to resist forces

resulting from certain hypothetical overload stages, significantly above loads

expected actually to occur in service. This design concept is known as STRENGTH

DESIGN.

2 . 6 TREND OF MAKING THE EARTH QUAKE RESISTANT STRUCTURES

2. 6.1 PRESENT PRACTICES IN PAKISTAN

Previously , in Pakistan there were no practices to make the structure earth quake

resistant and there were no consideration of the seismic forces but after the earth

quake of 8th

October 2005 special provisions are made & more consideration are

given to make the structure earth quake resistant. Now a days special provisions are

applied on the structures to make the structure earth quake resistant

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Figure 2.1 :

Columns and Beams are

provided in the masonary

structure to insure the box action

in the building of one or two

storey house and to give the

additional strength and stiffness

Figure 2.1

Figure2.2

Steel bars are provided at every

opening ( Window opening ) in

vertical directions

Figure 2.2

Figure 2.3

Columns are placed at each corner of

a building to insure the box action.

Shear stirrups

Special hook

Figure 2.3

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C H A P T E R

3

SSIIEESSMMIICCDDEESSIIGGNNOOFFSSTTRRUUCCTTUURREE

In Seismic Design of structure , we apply some special provisions on the structures such

that it can resist the earthquake forces. The aim of designing the structures

earthquakeresistant is that , the structure should be undamaged during the moderate

earthquake and it should not collapse during the severe earthquake to safe the life and

property.

3 . 1 PURPOSE.

The purpose of the earthquake provision here in is primarily to safeguard against

major structural failures and loss of life, not to limit damage or maintain function.

3 . 2 MINIMUM SEISMIC DESIGN

Structures and portions thereof shall, as a minimum, be designed and constructed

to resist the effects of seismic ground motions as provided in this division

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CHAPTER 3 Seismic Design of Structure

3 . 3 SEISMIC AND WIND DESIGN.

When the code-prescribed wind design produces greater effects,the wind design

shall govern, but detailing requirements and limitations prescribed in this section

and referenced sections shall be followed.

3 . 4 SOME RELATED TERMS

BASE

Base is the level at which the earthquake motions are considered to be imparted to

the structure or the level at which the structure as a dynamic vibrator is supported.

BASE SHEAR

It is the total design lateral force or shear at the base of a structure.

BEARING WALL SYSTEM

It Is a structural system without a complete vertical load carrying space frame.

BUILDING FRAME SYSTEM

It is an essentially complete space frame that provides support for gravity loads.

COLLECTOR

It is a member or element provided to transfer lateral forces from a portion of a

structure to vertical elements of the lateral force resisting system.

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CONCENTRICALLY BRACED FRAME

It is a braced frame in which members are subjected primarily to axial forces.

DESIGN BASIS GROUND MOTION

It is that ground motion that has a 10 percent chances of being exceeded in 50

years as determined by a site specific hazard analysis or may be determined

from a hazard map

DESIGN RESPONSE SPECTRUM

It is an elastic response spectrum for 5% equivalent viscous damping used to

represent the dynamic effect of the Design groundmotion for the design of

structure. This response spectrum may be either a site-specific spectrum based

on geologic,seismological and soil characteristics associated with aspecific site

or may be a spectrumconstructed in accordance with the spectral shape.

DIAPHRAGM

It is a horizontal or nearly horizontal system acting to transmit lateral forces to

the vertical resisting system.

ELASTIC RESPONSE PARAMETERS

Elastic response parameters are the forces and deformations determined

from an elastic dynamic analysis using an unreduced ground motion

representation.

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ESSENTIAL FACILITIES

Those structures which are necessary for emergency operations subsequent to

natural disaster.

LATERAL FORCE RESISTING SYSTEM

It is the structural system designed to resist the Design Seismic Forces.

MOMENT RESISTING FRAME

It is the frames in which members and joints are capable of resist forces

primarily by flexure.

MOMENT RESISTING WALL FRAME

It is a masonry wall frame especially detailed to provide ductile behavior.

ORTHOGONAL EFFECTS

These are the earthquake load effects on structural system common to the

lateral force resisting systems along two orthogonal axes.

OVERSTRENGTH FACTOR

It is a characteristic of structures where the actual strength is larger than the

design strength. The degree of over strength is material and system-dependent.

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PEFFECT

It is the secondary effect on shears, axial forces and moments of

framemembers induced by the vertical loads acting on the laterally displaced

building system.

SHEAR WALL

It is wall designed to resist lateral forces parallel to the plane of the wall.

SHEAR WALL FRAME INTERACTIVE SYSTEM

Uses combination of shear walls and frames designed to resist lateral forces in

proportion to their relative rigidities, considering interaction between shear walls

and frames on all levels.

SPACE FRAME

It is a three dimensional structural system, without bearing walls, composed

of members interconnected so as to function as a self-contained unit with or

without the aid of horizontal diaphragms or floor bracing system.

STORY

It is the space between the levels. Story x is the story below level x.

STORY DRIFT

It is the lateral displacement of one level relative to the level above or below.

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STORY DRIFT RATIO

It is the ratio of story drift to story height.

STORY SHEAR

It is the summation of design lateral forces above the story under

consideration.

STRENGTH

It is the capacity of an element or a member to resist factored loads.

STRUCTURE

It is an assemblage of framing members designed to support gravity loads and

resist lateral forces.

3 . 5 CONSTRUCTION OF BUILDINGS IN SEISMIC REGION

All structures and their components shall be analysed for all phases of construction for a

high degree of structural competence, reliability and ease of construction, as per the

various standards & codes

3 . 5.1 DEAD LOADS

Dead loads are the vertical loads due to the weight of all permanent structural and non-

structural components of a building, such as walls, built-in & moveable partitions, floors,

roofs, and finishes including all other permanent construction.

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Dead loads also include the weight of all fixed services equipments, such as

piping, heating & air-conditioning equipments, elevators and the weights of all

other fixed equipments.

The vertical and lateral pressures of liquids are also treated as dead loads.

Dead loads shall be calculated from the unit weights given in UBC or from

the actual known weights of the materials used.

To provide for partitions where their positions are not known on the plans, the

beams &the floor slabs (where these are capable of effective lateral distribution

of the loads) shall be designed to carry, in addition to other loads, a uniformly

distributed load per sqft of not less than one third of the weight per foot of the

finished partition but not less than 20 lb/ft2

(1 KPa), if the floor is to be used for

office purpose

DEAD LOADS

1 ).Roof Finishes including insulation

and water proofing treatment 55 psf. (2.75 KPa)

2 ).Floor Finishes:

i) Terrazzo/ Marble/ Local granite flooring 30 psf. (1.5 KPa)

ii) Ceramic/ Glazed/ Vinyl tiles flooring 30 psf. (1.5 KPa)

iii) Plain cement concrete flooring 20 psf. (1 KPa)

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3 ).Ceiling Finishes:

i) Plaster 5 psf. (0.25 KPa)

ii) False Ceiling including supporting structure 3 psf. (0.15 KPa)

4 ).Piping, Ducts, Cables: 10 psf. (0.5 KPa)

5 ).Masonry Walls as per actual location and weight

6 ).Light Partitions for Office areas 25 psf. (1.25 KPa)

7 ).Wall Finishes:

i) Plaster 5 psf. (0.25 KPa)

ii) Cladding with marble, granite etc. 15 psf. (0.75 KPa)

8 ).Fixed Service Equipments Mechanical/Electrical As per actual loads equipments for

example elevators, pumps, fan according to manufacturer's

coil units compressors etc. information.

9 ).Facades including glazing tiles etc. As per actual weight

3 . 5 .2 LIVE LOADS

Live loads are the loads superimposed by the use and occupancy of the building

not including the wind, seismic and temperature loads or dead loads.

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Live loads include loads due to intended use and occupancy of an area, personnel,

moveable equipments, lateral earth pressures, vehicle and impact loadings.

Floor live loads as per occupancy and intended use requirements. Unit live loads

are the minimum live loads for the design of the listed areas. For any area not

listed, minimum design live loads shall be in accordance with UBC. For elevators

and other moving loads, equipment manufacturer information shall be used for

wheel loads, equipment loads, and weights of moving parts. If not otherwise

specified by the equipment manufacturer, impact and lateral forces shall be in

accordance with UBC.

The floor area live load may be omitted from areas occupied by equipment whose

weight is specifically included in dead load. Live load is not omitted under

equipment where access is provided.

LIVE LOADS

1 ).Monument Deck Levels 125 psf. (6.25 KPa)

2 ).Libraries

i) Reading 60 psf. (3 KPa)

ii) Book storage area 150 psf. (7.5 KPa)

3 ).Mosques, Stairs 100 psf. (5 KPa)

4 ).Museum 80 psf. (4 KPa)

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5 ).Offices

i) Filling and storage space 100 psf. (5 KPa)

ii) Office for general use 50 psf. (2.5 KPa)

iii) Office with computing data 75 psf. (3.75 KPa)

processing and similar equipments.

6 ).

i) Corridors first floor 100 psf. (5 KPa)

ii) Corridors above first floor 80 psf. (4 KPa)

7 ).Roof

i) Accessible 40 psf. (2 KPa)

ii) Inaccessible 20 psf. (1 KPa)

3 . 5.3 DYNAMIC / VIBRATIONS LOADS

Dynamic effects caused by vibrating loads of equipment and

machinery such as pumps, fans, screens, and compressors shall be determined by

established analytical methods or design data from suppliers. It is intended to minimize

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the vibration effects as far as possible by the provision of shock absorbing materials in

accordance with supplier's Recommendations.

3 . 5.4 WIND LOAD

All loads due to the effect of wind pressure or suction shall be considered as wind

loads. The wind loads on the structure shall be calculated in accordance with

ANSI/ASCE 7 using the following formula:

qz = 0.00256 kz (IV)2

Where

V = Basic wind speed = 100 miles/hour

Kz = Velocity pressure Exposure coefficient I = Importance factor

qz = Velocity Pressure at height Z in pounds per square foot.

qz = 0.613 kz (IV)2

Where

V = Basic wind speed = 45 meter/sec

Kz = Velocity pressure Exposure coefficient I = Importance factor

qz = Velocity Pressure at height Z in N/m2

.

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3 . 5.5 SEISMIC LOADS

Earthquake load shall be computed using the ground motion values given in

Seismic Zoning Maps of the earthquake affected areas issued separately by NESPAK.

The seismic zoning maps show Peak Ground Acceleration (PGA) values for 10%

Probability of Exceedance in 50 years (500 years return period) and PGA values for 2%

Probability of Exceedance in 50 years (2500 years return period).

The PGA values shown on these maps are for firm-rock (shear wave velocity of 760

m/sec) site condition. For soil sites amplification of ground motion is introduced

therefore appropriate amplification factors should be used keeping in view the

geotechnical properties of the subsoil. Taking average shear wave velocity of 400m/sec

of the sub-soil in the earthquake affected areas, the average value of amplification factor

of 1.3 should be used.

3 . 5.6 THERMAL LOADS

The temperature effect will be investigated against a maximum differential

temperature of 20 degree centigrade for the frame structure.

In this project ( Design of farm house in seismic region ) we do not consider this load.

3 . 5.7 SHRINKAGE & CREEP

Shrinkage of reinforced concrete shall be considered as a

shortening of 0.04 inch per feet (3.33 mm per meter). This can be reduced to 0.02 inch

per feet (1.67 mm per meter), if effects of creep are included.

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3 . 5.8 SNOW LOADS

The roofs shall be designed for snow loads or live loads whichever is more

severe. Actual load due to snow will depend upon the shape of the roof and its capacity to

retain the snow; and each case shall be treated on its own merits. In the absence of any

specific information, the loading due to the collection of snow may be assumed to be 1.3

lbs/sq.ft per in (2.441 Pa per mm) depth of snow.( according toNESPAK)

3 . 6 STRUCTURAL SYSTEM

Structural elements e.g. slab, beams, columns, walls and footings are

combined in various ways to create structural systems for buildings. For the selection of a

suitable framing system for a building, the determining factors are:

a )Appearance, functional & aesthetic requirements.

b )Limitations on the size of structural members as imposed by architectural design

and practical constraints on the basis of structural considerations.

c )Clear spans and height required.

d )Loads, including special loads.

e )Availability of materials, skilled labor and construction equipments.

f ) Integration of structure with respect to architectural details, mechanical

equipment, occupancy requirements etc.

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g )Economy, not merely in structural system but also the overall economy in the

finished structure.

Except for the very simple and ordinary structure, study of several alternative systems,

materials and layouts shall be made, before the final scheme is set. From many

alternatives, the criteria for the selection of the best structural system for a building

would be its compliance with the functional and aesthetic requirements in an efficient and

in technically sound manner.

3 . 7 EXPANSION AND SEPARATION JOINTS

Arrangements of these joints shall be made on the following principles: Joints shall

be provided only to avoid extremely irregular plan shapes & to avoid excessively long

interconnected structures. In general, maximum interconnected length shall be limited to

about 150 feet (46 meter). This is acceptable only if the structure is temporarily separated

at about 65 feet (20 meter) long intervals or less by "shrinkage control pour strips" which

are left open for at least 30 days after placement of concrete on each side.

Width of joint will be at least 1 inch (25 mm).

Double columns shall be provided at isolation joints.

3 . 8 FOUNDATIONS AND SUBSTRUCTURE

The bearing capacity of the soils and other factors pertaining to foundation design

shall be evaluated as per recommendations laid down in the soil investigation report. In

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case no soil investigations are carried out, an allowable bearing capacity of 0.75 t/ft2

(8.07

t/m2

) may be adopted for small residential units.( Nespak )

The foundation and the substructure requirement depend on the soil type and the seismic

zone.

3 . 9 METHOD OF ANALYSIS

The analysis shall be carried out using computer aided methods of

analysis and design as listed below using well reputed compute software e.g..

a) SAP-2000 - Structural Analysis Programme (Static & Dynamic Finite element

Analysis of Structure).

b)STAAD-Pro - Structural Analysis and Design Program

c )Etabs Extended three Dimensional Analysis of Building Systems

3 . 10 FOR SINGLE TO TWO STOREY HOUSING UNITS

3 . 10.1 MATERIALS (for construction of houses in earthquake prone areas)

MASONRY UNITS:

- Concrete block work

- Cut-stone masonry

- Burnt clay brick

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Avoid using random rubble masonry

The bricks shall be of standard shape, burnt red, hand formed or machine made and shall

have a minimum crushing strength of 1500 psi (10 N/mm

2

). The concrete block shall be

solid blocks of 12 x 8 x 6 (300mm x 200mm x 150mm) made with 1:2:4 mix

MORTAR:

Cement-sand mixes of 1:6 and 1:4 shall be adopted for one-brick and half- brick

thick walls, respectively. The addition of small quantities of freshly hydrated lime

to the mortar in a lime-cement ratio of 1/4:1 to 1/2:1 will increase its plasticity

greatly without reducing its strength. Where steel reinforcing bars are provided,

the bars shall be embedded in a cement-sand mortar not leaner than 1:4, or in a cement

concrete mix of 1:2:4

PLASTER:

All plasters shall have a cement-sand mix not leaner than 1:6 on outside or inside

faces. It shall have a minimum 28 days cube crushing strength of 450 psi (3 N/mm2

) . A

minimum plaster thickness of 3/8 (10 mm) shall be adopted.

3 . 10.2 STRUCTURAL FORM AND BUILDING CONFIGURATION

A ) Avoid creating heavy concentrated masses, particularly at roof level (eg.

large water tanks).

B )Make sure no heavy masses are located above stairwells etc.

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C )Avoid irregular floor plan shapes to avoid torsional effects in earthquakes.

D )Make sure columns and walls are continuous between floors.

E )Make sure buildings do not have large openings (eg. for garages or shops) as

these can weaken structure and cause torsional effects.

F ) Make sure that buildings plan shape at any floor level, including ground

floor, is symmetrical.

G ) If shear walls are concentrated inside a building make sure it will not be

subject to torsional effects or design structure, to resist this.

H ) Make sure structure is not long in relation to its width (W). Avoid long

unsupported walls of longest length (L) does not exceed 3 W.

3 . 10.3 HORIZONTAL REINFORCEMENT IN WALLS

Horizontal reinforcing of walls is required in order to tie orthogonal walls

together. The most important horizontal reinforcing is by means of reinforced concrete

bands provided continuously through all load-bearing longitudinal and transverse walls at

plinth, lintel and roof-eave levels and also at the top of gables according to the

requirements stated below.

3 . 10.4 PLINTH BAND

This should be provided in those cases where the soil is soft or uneven in its properties. It

may also serve as damp-proof course.

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3 . 10.5 LINTEL BAND

A lintel band shall be incorporated in all openings and shall be continuous over all

interior and exterior walls. The reinforcement over the openings shall be provided in

addition to that of any other requirement.

3 . 10.6 ROOF BAND

This band shall be provided at the eave-level of trussed roofs and also below gable levels

on such floors which consist of joists and covering elements so as to integrate them

properly at their ends and fix them into the walls. This band is not required in case of

reinforced concrete or reinforced brick masonry slabs.

The width of the RC bands (at plinth and lintel) shall be the same as the thickness of the

wall. The minimum thickness of a load-bearing wall shall be 9 inches (225 mm). A cover

of one inch from the face of wall shall be maintained for all steel reinforcing.

The vertical thickness of the RC bands may be kept to a minimum of 6 (150 mm) with 4

(115 mm) bars as reinforcement. For economical reasons a minimum

thickness of 3 (75 mm) with 2 (65 mm)bars may be adopted.

The concrete mix is to be 1:2:4 by volume. Alternatively, it shall have a minimum

compressive cylinder strength of 2500 psi (17 N/mm

2

) at 28 days.

The longitudinal bars shall be held in position by steel stirrups 3/8 (10mm) placed 6

(150 mm) centre to centre.

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3 . 10.7 VERTICAL REINFORCEMENT IN WALLS

Steel bars shall be installed at the critical sections (i.e. the corners of walls, junctions of

walls, and jambs of doors) right from the foundation concrete. They shall be covered with

cement concrete in cavities made around them during the masonry construction. This

concrete mix should be kept to 1:2:4 by volume, or richer.

The vertical steel at openings may be stopped by embedding it into the lintel band, but

the vertical steel at the corners and junctions of walls must be taken into either the floor

and roof slabs or the roof band.

. 3 . 10.8 VERTICAL JOINTS BETWEEN ORTHOGONAL WALLS

For convenience of construction, builders prefer to make a toothed joint which is later

often left hollow and weak. To obtain full bond, it is necessary to make a sloped or

stepped joint. It should be constructed so as to obtain full bond by making the corners

first to a height of 24 inches (600 mm), and then building the wall in between them.

Alternatively, the toothed joint shall be made in both the walls in lifts of about 18 inches

(450 mm).

3 . 10.9 DOWELS AT CORNERS AND JUNCTIONS

Steel dowel bars shall be provided at corners and T-junctions to integrate box action of

the walls. Dowels are to be taken into the wall to sufficient length so as to provide their

full bond strength.

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3 . 11 GUIDELINES FOR MULTI-STOREY FRAME STRUCTURES

3 . 11.1 MATERIAL TYPES FOR WALLS

- Concrete block work units

- Cut-stone masonry units

- Reinforced Concrete walls (expensive alternative)

- Factory manufactured brick units

- Avoid using random rubble masonry

3 . 11.2 FOUNDATIONS

- Check soil type and water level.

- Use reinforced concrete strip footings under main load bearing walls and

columns.

- Soft clays and loose-medium dense sand, which is waterlogged, may liquefy

during an earthquakes. Seek specialist advice on piled foundations and

structural design.

3 . 11.3 MASONRY SHEAR WALLS

Masonry walls acting as non-structural shear walls to resist lateral shaking:

- Make sure walls are made with good strength

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- Make sure wall are build first and use shutters for columns to give strong

bonding between masonry walls and column.

- All masonry units to be bonded with mortar, of 1 part cement to 3 parts sand

- Make sure all walls are continuous from foundations to roof level.

- Make sure masonry buildings is tied to floors and columns at suitable intervals

3 . 11.4 REINFORCED CONCRETE WALLS

- These can be combined with columns to provide additional shear resistance

against earthquakes.

3 . 11.5 MINIMUM BEAM, COLUMN AND SLAB SIZES

10 ft (3 m) span concrete floor slabs, minimum depth 150 mm

15 ft (4.5 m) span beams, minimum 18 inch x 12 inch (450mm x 300mm)

Concrete columns average 12 inch x 12 inch (300mm x 300mm)

- Make sure that all main reinforcing bars in concrete are high yield deformed bars,

not plain bars.

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59

DDEESSIIGGNNMMEETTHHOODDOOLLOOGGYY

Over the past several decades the strength design method has largely displaced the older

service load design methods both in Pakistan and abroad because in this method, individual

load factors may be adjusted to represent different degree of uncertainty for the various

types of loads and strength reduction factors likewise may be adjusted to the precision with

which various types of strength (bending, shear, torsion, etc.) Therefore, throughout in the

design of this building, strength design is followed. In this project we design the farm house

first manually & we provide the plinth band , lintel band & roof band for making the

building earthquake resistant. Also the steel bars are provided in the masonary walls. We are

following the ACI 2005 & UBC-97 codes.We use the excel sheets for the manual

calculations.

C H A P T E R

4

Also the analysis and design results are taken from the ETABS by converting the load

bearing wall structure ( farm house ) into frame structure .

4 . 1 TWO-WAY SLABS

These are the slabs that are essentially supported on more than two faces. A term "aspect

ratio" is sometimes defined for the slab that is the ratio of shorter to longer span. For a slab

to be two-way, this ratio must lie between 0.5 and 1, both values included.


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CHAPTER 4 Design Methodology

4 . 1.2 DESIGN BY THE COEFFICIENT METHOD

A unified method in the two way slab design was presented in 1963 ACI code. Its use

spread all over the world for the design of such slabs and its continued use is permissible

under the code provision .

The method makes use of tables of moment coefficients for variety of conditions.

Unit width strip is taken in both directions. The strip is designed separately for +ve and ve

moment

2nuu LCM =

C = ACI co-efficient

u= Factored slab load

C depends upon the end conditions of slab and the aspect ratio.

Three tables are available for C

Dead load positive moment

Live load positive moment

-ve moment

4 . 2 FOR ONE-WAY SLAB

4 . 2.1 DESIGN PROCEDURE

1 ).Check whether the slab is one-way or two-way.

2 ).Calculate hminand round it to higher 10mm multiple.

i. Not less than 110 mm for rooms

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ii. Not less than 75 mm for sunshades.

3 ).Calculate dead load acting on the slab.

Dead Load = Load per unit area x 1m width.

4 ).Calculate live load acting on the slab.

Live load = Load per unit area x 1m width.

5 ).Calculate total factored load per unit strip. (kN/m)

6 ). Calculate the moments either directly (simply supported) or by using coefficient for

continuous slabs.

7 ).Calculate effective depth.

d = h (20 + ()db)

db= 10, 13, 15, generally used.

8 ).Check that

d dmin

9 ).Calculate As required for 1m width.

10 ).Calculate minimum/distribution/temperature & shrinkage steel.

11 ).Select diameter and spacing for main and steel.

12 ).Check the spacing for max. and min. spacing.

smin 90mm

if spacing is less than minimum increase the diameter of bar.


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13 ).For continuous slabs, curtail or bend up the +ve steel. For -ve steel see how much steel

is already available. Provide remaining amount of steel.

14 ).Calculate the amount of distribution steel. Decide its dia. & spacing like main steel.

15 ).Check the slab for shear.

vVcVu

16 ).Carry out detailing and show results on the drawings.

17 ).Prepare bar bending schedule, if required

4 . 3 BEAMS

All the Beams in a farm house are not a structural Beam as they are not provided to take the

transverse load (to resist the bending).They are provided to insure the box action. They are

provided to increase the ductile nature of the masonary structure. They give additional

strength and stiffness.

The minimum steel Area is provided on these Beams

min = 0.0018 for Grade 420 MPa

As min. = 0.0018 x b x h

They are provided at the Plinth Level , at the Lintel Level , at the Roof Level

4 . 3.1 DESIGN OF STRUCTURAL BEAMS

4 . 3.1.1 DESIGN PROCEDURE FOR SIMPLY SUPPORTED BEAMS

1 ) Calculate self weight of the beam

2 ) Calculate the Slab Load


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3 ) Calculate the total factored load that is subjected to beam

4 )Determine the clear span of the beam ln

5 )Find the moment

M = wu ln2

88

6 )Determine the dmin

7 )Provide a clear cover of 40mm.

8 )Calculate h.

9 )Calculate

= w x [1- [(1-0.216R/fc')]

w = 0.85 fc' / fy

R = Mu / ( bd2

)

10 )Check against min

min = 1.4 / fy

11 )Calculate the area of steel

12 )Select the no of bars according to the calculated area of steel

4 . 3.1.2 DESIGN PROCEDURE FOR DOUBLY REINFORCED BEAMS

1 ) Calculate self weight of the beam

2 ) Calculate the Slab Load

3 ) Calculate the total Factored load that is subjected to beam

4 )Determine the clear span of the beam ln

5 )Find the moment "M"

6 )Calculate dmin


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7 )If dmin is greater than the h req then design the beam as a doubly reinforced.

8 )Calcute d' / d

9 )Determine ( 600 fy ) / 1600

If ( 600 fy ) / 1600 < d' / d so compression steel will be yielded.

10 )max = 0.85 1x 3fc' / (8 fy)

11 )Calculate As1= maxx b x h ( tension steel area )

12 )Calcute a = 0.85 1 x 3d / 8

13 )Determine M1

M1= x As1x fy x ( d - ( a / 2 ))

14 )Determine M2

M2= M - M1

15 )Calculate As' = M2 / (x fy x ( d d' )) ( compression steel area )

16 )As = As1+ As'

17 )Calculate the no of bars for the tension steel area and also for the compression steel

area.

4 . 3.1.3 DESIGN PROCEDURE FOR CONTINUOUS BEAM

1 ) Calculate self weight of beam

2 ) Calculate the slab load

3 ) Calculate the total Factored load that is subjected to beam.

4 ) Calculate the moments at the ;

Negative moment at the exterior face of exterior support

Negative moment at the exterior face of the first interior support

Negative moment at the interior face of first interior support


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Exterior span positive moment

Interior span positive moment

5 )From these moments find the corresponding area of steel and then the no of bars

corresponding to the steel area

4 . 4 DESIGN OF LINTELS

4 . 4.1 WALL LOAD ON THE LINTEL

Equivalent UDL on lintel if height of slab above lintel is greater than 0.866L

UDL = 0.11 x twx L

tw= wall thickness in "mm"

L = opening size in "m"

If the height of slab above lintel is less than 0.866L

Total Wall Load + Load from slab incase of load bearing wall

UDL = ( Equivalent width of slab supported ) x ( Slab Load per unit area )

= m x KN / m2 = KN / m

After the calculation of the load the rest of the design is same as the beam

4 . 5 COLUMNS

The minimum area of steel is provided is provided in the columns of a farm house which are

provided for the purpose to insure the box action & to give additional strength to the

masonary design of a farm house. These columns are not for the purpose to take the axial

loads and moments.( Non Structural columns )

Special provisions are applied for the detailing ( Seismic provisions ).e.g Lap is provided at

the centre of the columns.


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4 . 5.1 DESIGN PROCEDURE FOR THE STRUCTURAL COLUMNS

( AXIAL LOAD + MOMENTS )

1 ) Find the PD, PL, Mux , Muy

2 )Calculate the size of the Column using the following formula

Ag = Pu +2Mux+2Muy

0.5fc' + 0.01 fy3 ) Calculate the " "

4 ) Calculate ex, ey & eox

ey = Mux / Pu , ex = Muy / Pu , eox = ex+eyx b h

5 ) Use interaction curves and charts to determine

6 ) From these value find the area of steel for the longitudinal bars and then decide the noof bars.

7 ) Check the provided

0.01 < provided < 0.03

8 ) Transverse reinforcement

9 ) Spacing of shear stirrups

10 )Calculate the lap length

l = 0.093 fy db

4 . 6 WALL DESIGN & FOUNDATIONS

4 . 6.1 DESIGN OF MASONARY FOUNDATION

W = Load per unit length of wall.

W = li 385 + ( hi ti ) x1920 + ( qi li )0.5 (kg/m)

L = Width of the footing = W 10 F(qa-10D)


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Li = Clear span of each slab or the panel ( m )

hi = Height of each floor ( m )

ti = Thickness of wall of each storey (m).

Qi = Allowable partition load (kg/m^2)

L = Width of footing in mm

qa = Allowable bearing capacity in KPa.

F = 1.0 for interior footing

F = 1.35 for exterior footing

D = Depth of bottom footing from plinth level (m)

No of Steps = L 2h t

114

4 . 6.2 THICKNESS OF WALL

If the load W is divided by compressive strength of brick it will give us wall thickness at the

section. Normally thickness of wall is expressed in no. of half bricks.

No of half bricks = W 2 /2

4500

Where

2 = 1 for interior wall

2 = 1.5 forexterior wall

(Only for 1:6 mortar)


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4 . 6.3 DESIGN PROCEDURE FOR ISOLATED FOOTING

1 )Collect all the required information i.e allowable bearing capacity , depth of footing ,

type of load coming and decide type of footing.

2 ) For service DL , LL and net allowable bearing capacity find the size of footing.

3 ) Select or assume a suitable depth of footing satisfying two way punching shear.

4 ) Calculate the net factored contact pressure "qnu" at the interface of soil and concrete

surface.

5 )Calculate one way shear in longer direction and check for its capacity.

6 ) Calculate the moment in shorter and longer direction.

7 ) Calculate the total amount of steel in shorter and longer direction and find the spacing.

8 ) Check the bearing pressure at the bottom of column.

9 ) Check the development length for the steel provided.

4 . 7 DESIGN OF STAIRS

1 ) Calculation of span of slab

2 ) Depth of slab

3 ) Loads calculation

4 ) Calculation of Moments

5 ) Steel calculations & spacing

6 ) Check for maximum spacing.

7 ) Shear check.

8 ) Detailing.


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4 . 8 SOFTWARES USED IN DESIGN OF FARM HOUSE AS FRAME

STRUCTURES

We use the software ETABS for the design of farm house as frame structure.

4 . 8.1 OVERVIEW OF ETABS PROGRAM

ETABS ( Extended Three dimentional Analysis of Building System ) is a stand-alone finite-

element-based structural analysis program with special purpose features for structural design

and analysis of building systems. The analysis methods include a wide variety of Static and

Dynamic Analysis Options. We can import our file ( Plan of a complex building ) from the

AUTOCAD to the ETABS.

4 . 8 .2 PROCEDURE FOR MODELING IN ETABS

Step 1

Begin a New Model

In this Step, the dimensions and story height are set. Then a list of sections that fit the

parameters set by the architect for the design are defined.

Figue 4.1: ETABS user interface

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A. Change the units in the lower right corner in the drop down box according to our

desired units.

B. Click the File menu > New Model command or the New Model button.

Figue 4.2:The New Model Initilization form

C. Select the Nobutton on that form and the form. The Building Plan Grid System and

Story Data form is used to specify horizontal grid line spacing, story data, and, in

some cases, template models. Template models provide a quick, easy way of starting

your model. They automatically add structural objects with appropriate properties to

your model. It is highly recommend to start models using templates whenever

possible. However, in this project , we import the drawing from the AUTOCAD .

D. Set the number of stories.

E. Type 11 ftin the bottom storey height.

F. Then click grid only

G. Click the OK button to accept your changes. When you click the OK button, your

model appears on screen in the main ETABS window with two view windows tiled

vertically, a Plan View on the left and a 3-D View on the right.The number of view

windows can be changed using the Options m

form house design

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