design & construction of shear wall

8/13/2019 Design & Construction of Shear Wall

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DESIGN AND CONSTRUCTION OF SHEAR WALLS

PROJECT REPORT


A PROJECT REPORT SUBMITTED TO JNTU, HYD

BACHELOR OF TECHNOLOGY

IN

CIVIL ENGINEERING

BY

K.BHASKER RAO 09241A0163

A.KAMAL TEJ 09241A0169

MD.BASEERUDDIN 09241A0176

B.RAVI TEJA 09241A0191

B.SANTHOSH REDDY 09241A01A1

DEPARTMENT OF CIVIL ENGINEERING

GokarajuRangaraju Institute of Engineering & Technology

Bachupally HYDERABAD-500 090


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CERTIFICATE

This is to certify that project entitled DESIGN AND CONSTRUCTION OF SHEAR WALLS

that is being submitted by K.BhaskerRao (09241A0163), A. Kamal Tej (09241A0169), Md.

Baseeruddin (09241A0176), B. Ravi Teja (09241A0191), B.Santhosh Kumar Reddy

(09241A01A1) in partial fulfillment of the requirement for the award of Degree of Bachelor of

Technology in Civil Engineering and Technology ( Affiliated to Jawaharlal Nehru Technological

University, Hyderabad) is a record of bonafide work carried out by them under my guidance and

supervision. The results embodied in this thesis have not been submitted to any other University

or Institute for the award of any degree.

Dr.G.VENKATA RAMANAMr. G.V.V Satyanarayana

Head of the Department Associate Professor

Civil Engineering Department Civil Engineering Department

G.R.I.E.T, ` G.R.I.E.T

Hyderabad Hyderabad


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ACKNOWLEDGEMENT

Success is epitome of hard work, congency for fulfilling the mission, indefatigable perseverance

and most of all encouraging guidance and steering.

We express our sincere thanks to, Dr. Jandhyala Murthy principal, GRIET for the support and

motivation provided to us.

It gives us immense pleasure to express our gratitude to Prof. Dr. G.VenkataRamana , Head of

the department of Civil Engineering and all the faculty of civil engineering department ,for their

esteemed guidance and able supervision during the course of project. Their constant

encouragement and Co-operation made this project a success.

It also gives us immense pleasure to express our gratitude to Associate Prof.Mr.G.V.V.

Satyanarayana who has been always helping out in design of shear wall, his supervision during

the course of our project has been proved as an greatest asset to our project.

We would like to express our sincere thanks to Cybercity and Ashoka builders,

for providing us an opportunity to complete our main project successfully, which is part of our

course curriculum. The training would not have successfully completed without the guidance of

Mr. Kiran (Structural Engineer) and Mr. Sudheer (Assistant Project Manager)


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DECLARATION

We hereby declare that the work presented in this project titled Design and Construction of

Shear walls submitted towards completion of main-project in Seventh Semester of B.Tech(CIVIL ENGINEERING) at the GokarajuRangaraju Institute of Engineering and Technology

affiliated to Jawaharlal Nehru Technological University, Hyderabad is authenticate work and had

not been submitted to any University or Institute for any award.

K.BHASKER RAO (09241A0163)

A.KAMAL TEJ (09241A0169)

MD.BASEERUDDIN (09241A0176)

B.RAVI TEJA (09241A0191)

B.SANTHOSH REDDY (09241A01A1)


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Abstract

Besides, food and clothing, shelter is a basic human need. India has been successful in

meeting the food and clothing requirements of its vast population; however the problem of

providing shelter of all is defying solutions. While there has been an impressive growth in the

total housing stock from 65 million in 1947 to 187.05 million in 2001, a large gap still exists

between the demand and supply of housing units. The Working Group on Housing for the 9th

five-year plan estimated the housing shortage in 2001 at 19.4 million units- 12.76 million in rural

area and 6.64 million in urban area. The shortage of housing is acutely felt in urban areas more

so in the 35 Indian cities, which according to the 2001 census have a population of more than a

million.

Hence in order to overcome this problem construction process should be quick, tall and

effective to accommodate huge population in a given area. So we have chosen this topic of

DESIGN AND CONSTRUCTION OF SHEAR WALLS. This type of shear wall construction

helps to build tall structure of about 20 floors within no time. Hence the construction process will

become much quicker and efficient.

Constructions made of shear walls are high in strength ,they majorly resist the seismic

force, wind forces and even can be build on soils of weak bases by adopting various ground

improvement techniques. Not only the quickness in construction process but the strength

parameters and effectiveness to bare horizontal loads is very high. Shear walls generally used inhigh earth quake prone areas, as they are highly efficient in taking the loads. Not only the earth

quake loads but also winds loads which are quite high in some zones can be taken by these shear

walls efficiently and effectively.

Though these types of constructions have their origin in western nations in early 90s,

this ideology has changed rapidly and spread all over the world with in no time. The form work

used in this type of construction is of a new kind in Indian construction scenario.

Certain patented systems based on imported technologies such as Mascon System

(Canada), Mivan System (Malaysia) have come on the Indian scene in recent years. In these

systems traditional column and beam construction is eliminated and instead walls and slabs are

cast in one operation at site by use of specially designed, easy to handle (with minimum labor

and without use of any equipment) light weight pre-engineered aluminum forms. Rapid

construction of multiple units of a repetitive type can be achieved with a sort of assembly line

production by deployment of a few semi-skilled labors.


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The entire operation essentially comprises fitting and erecting the portion of shuttering as

already determined (the optimization in use is determined by appropriate planning) and then

carrying out concreting of the walls and slabs. Props are so designed that they stay in position

while de-shuttering of slabs and/or takes place. The dimensional accuracy of the formwork is of

high order. Therefore any possibility of errors does not rise. Though this type of constructions

are cost effective, still in order to build a better society and for satisfying present need of shelter ,

shear wall construction are going to be a solution to this problem of shelter in our nation.

The main idea of we taking this topic of Design and construction of shear walls is the

challenging task in designing of shear walls. Shear walls have a peculiar behaviour towards

various types of loads. Calculation of rigidity factor, reactions, shear center, shear force and

bending moment is a topic of interest. Hence by adopting the technologies used in Cyber City,

Rainbow Vista, Near IDPL road, Moosapet, to the college building of GRIET fourth block, we

are going to check the building behaviour. We are also verifying and designing this same

structure using extended three dimensional analysis of buildings (ETABS) software.

As said by Benjamin Franklin An investment in knowledge pays the best interest. We would

like to invest our knowledge to whatever extent we can and design the building most efficiently

CONTENTS

TITLE PAGE NO:

CHAPTER 1: Introduction

1.1 Definition

1.2 Scope of the work

1.3 Objective

1.4 Organization


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CHAPTER 2: Literature Review

2.1 Review of Literature

CHAPTER 3: Shear Walls

3.1 Purpose of constructing shear wall

3.2 Comparison of shear wall with conventional

Load bearing wall

3.3 Forces acting on shear wall

3.4 Classification of shear wall

3.5 Types of shear walls

CHAPTER 4: Manual design of shear wall

4.1 Introduction

4.2 Calculation of rigidity values

4.3 Calculation of shear centre

4.4 Calculation of seismic and shear forces at

Different floors in collegebuilding

4.5 Design the ductile shear wall for college building

CHAPTER 5: Design of college building using E-Tabs

5.1 Marking of columns, beams

5.2 Drawing floor area

5.3 Assigning of loads

5.4 Analysis

5.5 Results

CHAPTER 6: Construction of shear walls


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6.1 Excavation

6.2 Foundation and Footings

6.3 Bottom three floors and Waffle slab

6.4 Shear wall construction

6.5 Mivan formwork

6.6 Wall ties, Pins and Wedges

6.7 Electrical boards and Plumbing lines

6.8 Concreting

6.9 Curing

6.10 Holes in the slab

6.11 Electrical and Plumbing lines after Concreting

6.12 Painting and Finishing

CHAPTER 7: Scope for future work

CHAPTER 8: Conclusion

CHAPTER 9: References

Chapter 1


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INTRODUCTION

1.1 Definition

Shear walls are vertical elements of the horizontal force resisting system. Shear walls are

constructed to counter the effects of lateral load acting on a structure. In residential construction,

shear walls are straight external walls that typically form a box which provides all of the lateral

support for the building. When shear walls are designed and constructed properly, and they will

have the strength and stiffness to resist the horizontal forces.

In building construction, a rigid vertical diaphragm capable of transferring lateral forces

from exterior walls, floors, and roofs to the ground foundation in a direction parallel to their

planes. Examples are the reinforced-concrete wall or vertical truss. Lateral forces caused by

wind, earthquake, and uneven settlement loads, in addition to the weight of structure and

occupants; create powerful twisting (torsion) forces. These forces can literally tear (shear) abuilding apart. Reinforcing a frame by attaching or placing a rigid wall inside it maintains the

shape of the frame and prevents rotation at the joints. Shear walls are especially important in

high-rise buildings subjected to lateral wind and seismic forces.

In the last two decades, shear walls became an important part of mid and high-rise residential

buildings. As part of an earthquake resistant building design, these walls are placed in building

plans reducing lateral displacements under earthquake loads. So shear-wall frame structures are

obtained.

Shear wall buildings are usually regular in plan and in elevation. However, in some buildings,

lower floors are used for commercial purposes and the buildings are characterized with larger

plan dimensions at those floors. In other cases, there are setbacks at higher floor levels. Shear

wall buildings are commonly used for residential purposes and can house from 100 to 500

inhabitants per building

1.2 Scope of the work

The aim of the shear wall is to investigate the different ways in which the tall structures can bestabilized against the effects of strong horizontal wind loading and seismic loading.Some other reasons why we use shear walls are tall structures can be constructed which reduces

the area used and we can accommodate a large population in that particular area.Other objective is to construct a cost effective structure in less period of time.

This study helps in the investigation of strength and ductility of walls.


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The scope is to analyze the constructed shear wall that is to be constructed. Firstly the model isimplemented into known computer software and then it is analyzed based on the investigation of

strength and ductility.The strength of shear walls tested are compared with the calculated strengths based on design

codes.

1.3 Objective

Shear walls are not only designed to resist gravity / vertical loads (due to its self-weight and

other living / moving loads), but they are also designed for lateral loads of earthquakes / wind.

The walls are structurally integrated with roofs / floors (diaphragms) and other lateral walls

running across at right angles, thereby giving the three dimensional stability for the building

structures.

Shear wall structural systems are more stable. Because, their supporting area (total cross-

sectional area of all shear walls) with reference to total plans area of building, is comparatively

more, unlike in the case of RCC framed structures.Walls have to resist the uplift forces caused by

the pull of the wind. Walls have to resist the shear forces that try to push the walls over. Walls

have to resist the lateral force of the wind that tries to push the walls in and pull them away from

the building.

Shear walls are quick in construction, and in a country like India where shelter is very important

in a short lapse of time shear walls can be built very quickly.The precision to which they are

built is also very high compared to normally built brick structures. Hence the key objective of

shear wall is to build a safe, tall, aesthetic building.

1.4 Organisation

The colors of the rainbow light up your life at Rainbow Vistas. For the discerning individual andfor those to whom quality of life is something they care about Rainbow Vistas is a 4.3 acres

450 luxury apartments the best option and only solution. This dream housing project isstrategically located near HI-TECH City, MMTS and the citys IT hub on one side and prime

residential area on the other. A prestige project jointly promoted by Ashoka Developers andBuilders Ltd and Cybercity Builders and Developers Pvt. Ltd, Rainbow Vistas adds value to your

dream. Rainbow Vistas is approved by GHMC and all leading banks and institutions offer loans

for the property. The project has the first Hill-top club house and construction work is at fullswing.We are most obliged to have our main project being done in Rainbow Vistas, as a part of our

fulfillment of bachelors degree. They have been very patient, co operativethrough out our mainproject. The information given by them is immense and very useful in completion of our project


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Chapter 2

Literature Review

Review of literature:

Development of shear wall system for construction has advanced dramatically over the past few

years. Shear wall systems were initially developed to reduce damage due to earth quakes labour

requirements, increase strength of the building, shorten construction time reduce cost increase

quality of life.

U.H. Varyani described about shear walled buildings under horizontal loads. Considering in his

design Reinforced concrete framed buildings are adequate for resisting both the vertical and the

horizontal loads acting on shear walls of a building.In his 2nd

edition 2002 of Design of

structures. He gave rigidity of shear wall, torsional rigidity and shear center of a building in a

detailed description.

S.K. Duggal on his profound interest on structures gave a detailed description about reinforced

concrete buildings in his book Earth quake resistant design of structures describing a wall in a

building which resist lateral loads originating from wind or earthquakes are known as shear

walls. He considered flexural strength in the wall to be dominant force based on which design

of structure to be carried out in tall shear walls. He described in detail about various types of

shear walls with their load bearing capacities as per code requirements.

Mr A.P. Jadhav Associate Professor Rajarambapu Institute of technology rajaramnagar, Islampur

has given a detailed report on the form work used for the construction of shear walls.Mr.A.P.Jadhav highlighted the importance of quickness in construction and the need for

earthquake resistant building for better sustainability of life.

A report on effects of openings in shear walls on seismic response of structure by

sharminrizachowdhary, department of civil engineering dhake-1208, Bangladesh mostly focused


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on the design of shear walls with openings on seismic response using E-Tabs,i.e extended three

dimensional analysis of buildings. This report gives a detailed explanation of how ETABS can

be effectively used to design shear walls.

INDIAN STANDARD CODES:

I.S 456:2000

As per clause 32, design for wall describes, design of horizontal shear in clause 32.4 given

details of how shear wall have to be constructed.

I.S:1893 Criteria of Earth Quake resistant Buildings Part (3) page 23, clause 4.2 gives the

estimation of earth quake loads.

In IS: 13920:1993 it gives the ductile detailing of shear wall as per clause 9, where 9.1 gives

general requirements.

9.2 shear strength

9.3 give flexural strength

9.6 give openings in shear walls.

Ductile detailing, as per the code IS: 13920:1993 is considered very important as the ductile

detailing gives the amount of reinforcement required and the alignment of bars.


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Chapter 3

Shear Walls

Shear walls are vertical elements of the horizontal force resisting system. Shear walls are

constructed to counter the effects of lateral load acting on a structure. In residential construction,

shear walls are straight external walls that typically form a box which provides all of the lateral

support for the building. When shear walls are designed and constructed properly, and they will

have the strength and stiffness to resist the horizontal forces.

In building construction, a rigid vertical diaphragm capable of transferring lateral forces

from exterior walls, floors, and roofs to the ground foundation in a direction parallel to their

planes. Examples are the reinforced-concrete wall or vertical truss. Lateral forces caused by

wind, earthquake, and uneven settlement loads, in addition to the weight of structure and

occupants; create powerful twisting (torsion) forces. These forces can literally tear (shear) a

building apart. Reinforcing a frame by attaching or placing a rigid wall inside it maintains the

shape of the frame and prevents rotation at the joints. Shear walls are especially important in

high-rise buildings subjected to lateral wind and seismic forces.

In the last two decades, shear walls became an important part of mid and high-rise residential

buildings. As part of an earthquake resistant building design, these walls are placed in building

plans reducing lateral displacements under earthquake loads. So shear-wall frame structures are

obtained.

Shear wall buildings are usually regular in plan and in elevation. However, in some buildings,

lower floors are used for commercial purposes and the buildings are characterized with larger

plan dimensions at those floors. In other cases, there are setbacks at higher floor levels. Shear

wall buildings are commonly used for residential purposes and can house from 100 to 500

inhabitants per building

3.1 PURPOSE OF CONSTRUCTING SHEAR WALLS

Shear walls are not only designed to resist gravity / vertical loads (due to its self-weight and

other living / moving loads), but they are also designed for lateral loads of earthquakes / wind.

The walls are structurally integrated with roofs / floors (diaphragms) and other lateral walls

running across at right angles, thereby giving the three dimensional stability for the building


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structures.

Shear wall structural systems are more stable. Because, their supporting area (total cross-

sectional area of all shear walls) with reference to total plans area of building, is comparatively

more, unlike in the case of RCC framed structures.

Walls have to resist the uplift forces caused by the pull of the wind. Walls have to resist the shear

forces that try to push the walls over. Walls have to resist the lateral force of the wind that tries

to push the walls in and pull them away from the building.

Shear walls are quick in construction, as the method adopted to construct is concreting the

members using formwork.

Shear walls doesnt need any extra plastering or finishing as the wall itself gives such a high

level of precision, that it doesnt require plastering.

3.2 COMPARISONS OF SHEAR WALL WITH CONSTRUCTION OF

CONVENTIONAL LOAD BEARING WALLS

Load bearing masonry is very brittle material. Due to different kinds of stresses such as shear,

tension, torsion, etc., caused by the earthquakes, the conventional unreinforced brick masonry

collapses instantly during the unpredictable and sudden earthquakes.

The RCC framed structures are slender, when compared to shear wall concept of box like three-dimensional structures. Though it is possible to design the earthquake resistant RCC frame, it

requires extraordinary skills at design, detailing and construction levels, which cannot be

anticipated in all types of construction projects.

On the other hand even moderately designed shear wall structures not only more stable, but also

comparatively quite ductile. In safety terms it means that, during very severe earthquakes they

will not suddenly collapse causing death of people. They give enough indicative warnings such

as widening structural cracks, yielding rods, etc., offering most precious moments for people to

run out off structures, before they totally collapse.

For structural purposes we consider the exterior walls as the shear-resisting walls. Forces from

the ceiling and roof diaphragms make their way to the outside along assumed paths, enter the

walls, and exit at the foundation.


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3.3 FORCES ON SHEAR WALL

Shear walls resist two types of forces: shear forces and uplift forces. Shear forces are generated

in stationary buildings by accelerations resulting from ground movement and by external forces

like wind and waves. This action creates shear forces throughout the height of the wall between

the top and bottom shear wall connections.

Uplift forces exist on shear walls because the horizontal forces are applied to the top of the wall.

These uplift forces try to lift up one end of the wall and push the other end down. In some cases,

the uplift force is large enough to tip the wall over. Uplift forces are greater on tall short walls

and less on low long walls. Bearing walls have less uplift than non-bearing walls because gravity

loads on shear walls help them resist uplift. Shear walls need hold down devices at each end

when the gravity loads cannot resist all of the uplift. The hold down device then provides the

necessary uplift resistance.

Shear walls should be located on each level of the structure including the crawl space. To form

an effective box structure, equal length shear walls should be placed symmetrically on all

four exterior walls of the building. Shear walls should be added to the building interior when

the exterior walls cannot provide sufficient strength and stiffness.

Shear walls are most efficient when they are aligned vertically and are supported on foundation

walls or footings. When exterior shear walls do not provide sufficient strength, other parts of the

building will need additional strengthening. Consider the common case of an interior wall

supported by a sub floor over a crawl space and there is no continuous footing beneath the wall.

For this wall to be used as shear wall, the sub floor and its connections will have to be

strengthened near the wall. For Retrofit work, existing floor construction is not easily changed.

Thats the reason why most retrofit work uses walls with continuous footings underneath them as

shear walls.

3.4 CLASSIFICATION OF SHEAR WALLS

Simple rectangular types and flanged walls (bar bell type)

Coupled shear walls

Rigid frame shear walls

Framed walls with in filled framesColumn supported shear walls

Core type shear walls


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3.5 TYPES OF SHEAR WALLS

RC Shear Wall

Plywood Shear WallMid ply Shear Wall

RC Hollow Concrete Block Masonry Wall

Steel Plate Shear Wall

RC SHEAR WALL:

It consists of reinforced concrete walls and reinforced concrete slabs. Wall thickness varies from

140 mm to 500 mm, depending on the number of stories, building age, and thermal

insulation requirements. In general, these walls are continuous throughout the building height;however, some walls are discontinued at the street front or basement level to allow for

commercial or parking spaces. Usually the wall layout is symmetrical with respect to at least one

axis of symmetry in the plan.

FIGURE:3.5.1 R.C. Shear wall

Floor slabs are either cast-in-situ flat slabs or less often, precast hollow-core slabs. Buildings are

supported by concrete strip or mat foundations; the latter type is common for buildings with

basements. Structural modifications are not very common in this type of construction.


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Reinforcement requirements are based on building code requirements specific for each country.

In general, the wall reinforcement consists of two layers of distributed reinforcement (horizontal

and vertical) throughout the wall length. In addition, vertical reinforcement bars are provided

close to the door and window openings, as well as at the wall end zones (also known as boundary

elements or barbells).

PLYWOOD SHEAR WALL

Plywood is the traditional material used in the construction of Shear Walls. The creation of pre-

fabricated shear panels have made it possible to inject strong shear assemblies into small walls

that fall at either side of a opening in a shear wall. As well as the use of a sheet steel, and steel-

backed shear panel (i.e. Sure-Board) in the place of structural use plywood in shear walls, has

proved to be far stronger in seismic resistance when used in shear wall assemblies.

FIGURE : 3.5.2 PLYWOOD SHEAR WALL

Plywood shear walls consist of:

Plywood, to transfer shear forces

Chords, to resist tension/compression generated by the over turning moments

Base connections to transfer shear to foundations.


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MIDPLY SHEAR WALL:

The MIDPLY shear wall is an improved timber shear wall that was developed by redesigning the

joints between sheathing and framing members, so that the failure modes observed in standard

wall testing are virtually eliminated at lateral load levels high enough to cause failures in

standard walls.

In MIDPLY shear wall design, one ply of sheathing material is placed at the center of the wall

between a series of pairs of studs oriented in a 90 rotated position relative to those in standard

shear walls

RC HOLLOW CONCRETE BLOCK MASONRY WALLS:

RHCBM walls are constructed by reinforcing the hollow concrete block masonry, by takingadvantage of hollow spaces and shapes of the hollow blocks. It requires continuous steel rods

(reinforcement) both in the vertical and horizontal directions at structurally critical locations of

the wall panels, packed with the fresh grout concrete in the hollow spaces of masonry blocks.

Reinforced Hollow Concrete Block Masonry (RHCBM) elements are designed both as load

bearing walls for gravity loads and also as shear walls for lateral seismic loads, to safely with

stand earthquakes. This structural system of construction is known as shear wall diaphragm

concept, which gives three-dimensional structural integrity for the buildings.

STEEL PLATE SHEAR WALL:

In general, steel plate shear wall system consists of a steel plate wall, boundary columns and

horizontal floor beams. Together, the steel plate wall and boundary columns act as a vertical

plate girder. The columns act as flanges of the vertical plate girder and the steel plate wall acts as

its web. The horizontal floor beams act, more-or-less, as transverse stiffeners in a plate girder.


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FIGURE : 3.5.3 PLATE SHEAR WALL

Steel plate shear wall systems have been used in recent years in highly seismic areas to resist

lateral loads. Figure shows two basic types of steel shear walls; unstiffened and stiffened with or

without openings.

ARCHITECTURAL ASPECTS OF SHEAR WALLS:

Most RC buildings with shear walls also have columns, these columns primarily carry gravity

loads (i.e., those due to self-weight and contents of building). Shear walls provide large strength

and stiffness to buildings in the direction of their orientation, which significantly reduces lateral

sway of the building and thereby reduces damage to structure and its contents.

Since shear walls carry large horizontal earthquake forces, the overturning effects on them are

large. Thus, design of their foundations requires special attention. Shear walls should be

provided along preferably both length and width. However, if they are provided along only one

direction, a proper grid of beams and columns in the vertical plane (called a moment-resistant

frame) must be provided along the other direction to resist strong earthquake effects.

Door or window openings can be provided in shear walls, but their size must be small to ensure

least interruption to force flow through walls. Moreover, openings should be symmetrically

located. Special design checks are required to ensure that the net cross-sectional area of a wall at

an opening is sufficient to carry the horizontal earthquake force.

Shear walls in buildings must be symmetrically located in plan to reduce ill effects of twist in


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buildings. They could be placed symmetrically along one or both directions in plan. Shear walls

are more effective when located along exterior perimeter of the building such a layout

increases resistance of the building to twisting.

Advantages of Steel Plate Shear Wall to Resist Lateral Loads:

1. The system, designed and detailed properly is very ductile and has relatively large energy

dissipation capability. As a result, steel shear walls can be very efficient and economical lateral

load resisting systems.

2. The steel shear wall system has relatively high initial stiffness, thus very effective in limiting

the drift.

3. Compared to reinforced concrete shear walls, the steel shear wall is much lighter which can

result in less weight to be carried by the columns and foundations as well as less seismic load

due to reduced mass of the structure.

4. By using shop-welded, field-bolted steel shear walls, one can speed-up the erection process

and reduce the cost of construction, field inspection and quality control resulting in making these

systems even more efficient.

5. Due to relatively small thickness of steel plate shear walls compared to reinforced concrete

shear walls, from architectural point of view, steel plate shear walls occupy much less space than

the equivalent reinforced concrete shear walls. In high-rises, if reinforced concrete shear wallsare used, the walls in lower floors become very thick and occupy large area of the floor plan.

6. Compared to reinforced concrete shear walls, steel plate shear walls can be much easier and

faster to construct when they are used in seismic retrofit of existing building.

7. Steel plate shear wall systems that can be constructed with shop welded-field bolted elements

can make the steel plate shear walls more efficient than the traditional systems. These systems

can also be very practical and efficient for cold regions where concrete construction may not be

economical under very low temperatures.


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Chapter 4

Manual design of Shear Walls

4.1 INTRODUCTION

The walls, in a building, which resist lateral loads originating from wind or earthquakes, are

known as shear walls. A large portion of the lateral load on a building, if not the whole amount,

as well as the horizontal shear force resulting from the load, are often assigned to such structural

elements made of RCC. These shear walls, may be may be added solely to resist horizontal

force, or concrete walls enclosing stairways, elevated shafts, and utility cores may serve as shear

walls. Shear walls not only have very large in-plane stiffness and therefore resist lateral load and

control deflection very efficiently, but may also help to ensure development of all available

plastic hinge locations throughout the structure prior to failure. The other way to resist such loads

may be to have the rigid frame augmented by the combination of masonry walls.

The use of shear walls or their equivalent becomes imperative in certain high-rise buildings, if

inter- storey deflections caused by lateral loadings are to be controlled. Well-designed shear

walls not only provide adequate safety, but also give a great measure of protection against costly

non-structural damage during moderate seismic disturbances.

The term shear wall is actually a misnomer as far as high-rise buildings are concerned, since a

slender shear wall when subjected to lateral force has predominantly moment deflections and

only very insignificant shear distortions. High-rise structures have become taller and moreslender, and with this trend the analysis of shear walls may emerge as a critical design element.

More often than not, shear walls are pierced by numerous openings. Such shear walls are called

coupled shear walls. The walls on both sides of the openings are interconnected by short, open

deep, beams forming part of the wall, or floor slab, or both of these. The structural engineer is

fortunate if these walls are arranged in a systematic pattern. The scope of the book limits the

discussion to shear walls without any openings.

This shows a building with the lateral force represented by arrows acting on the edge of each

floor or roof. The horizontal surfaces act as deep beams to transmit loads to vertical-resisting

elements-the shear walls A and B. These walls, in turn, act as cantilever beams fixed at their baseand transfer loads to the foundation. For the building plan additional shear walls C and D are

provided to resist the lateral loads that may act in the orthogonal direction. The shear walls are

subjected to the following loads: (a) A variable shear which reaches a maximum at the base.

(b) A bending moment which tends to cause vertical tension near the loaded edge and

compression at the far edge.

(c) A vertical compression due to ordinary gravity loading from the structure.


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Rigidity of a Wall Element Normal to the Direction of Horizontal Shear to Ensure Simple

Bending (,):is defined as the horizontal force necessary to prevent y-distortion of a wall element when Rxis applied in the x-direction producing a unit deflection. is also similarly defined. This givesthe directions of and for various positions of the angle section. When the principal axesof the shape of a shear wall are parallel to the X and Y axes, and vanish. Table 8.1 givesthe values of and calculated as explained by Benjamin.

4.1 Calculation of rigidity of a Shear Wall:

Torsional rigidity of a shear wall is defined as the torque required to produce a unit rotation. If a

torque T acting on a shear wall produces a rotation of radians, then the torsional rigidity of thewall is,

J=

The torsional rigidity of any given shape of a shear wall consists of the summation of its

torsional rigidities calculated on the basis of uniform and non-uniform torsional theories, theuniform-torsion theory component for open sections only, being given by,

= . Where 0 equals the perimeter of the section of shear wall of height h and thickness t. It,

however, works out to be negligibly small in the case of open sections such as channels, angles,

tees, etc. Being a function of the cube of thickness of shear wall, which is assumed to be very

small in comparison to its other dimensions. However, for box sections, it is not a small quantity,

as it is proportional to its thickness. The non-uniform torsion theory applied to flanged walls of

open cross-sections and gives approximate torsion rigidity based on the rigidities of separated

flanges opposite to each other, neglecting the web. Referring to for an I-section, rotation inradians due to a unit displacement of either flange on account of force is given by=,which is produced by a torque


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T= x aWhere = rigidity of the flange, i.e. a wall element of length b and thickness t.The torsional rigidity is, by definition, given on th basis of non-uniform torsion theory as,

= = x For box sections, the torsion due to non-uniform theory can be neglected. The torsional rigidity

of a shear wall is then given by,

J=+This gives the values of torsional rigidities of various shapes of shear walls.

Shear Centre of a Shear wall:

The shear center may be defined as the point through which the plane of loading must pass to

eliminate torsion. The shear centers of various shapes of shear walls. The rigidities,R, ,of a shear wall are all assumed to act through its shear center.This gives a summary of the rigidity characteristics of the various shapes of shear walls

frequently met with in practice, which have been evaluated on the principles discussed by

Benjamin and Timoshenko.

Shear Centre of a Shear Wall structure:

Shear centre of a shear wall structure in a story is the centre of rigidities of all the shear walls

which partake of the applied horizontal shear due to the infinite rigidity of the floor diaphragm.

The coordinates of the shear centre of a structure are fixed by taking moments of rigidities andand separately of rigidities and of all the shear walls about any convenient point O1and equating them to the corresponding moments of the summation of the above quantities

taking them to be concentrated at the shear centre of the structure. This gives assuming positive

sign for all forces

Where (x, y) give the location of the shear centre of the structure and the point chosen O1is the

origin of axes x1and y1 and the summation extends to all the shear walls joined monolithically

with the floor diaphragm. The equations are solved for x and y to locate the shear centre of the

structure, taking proper signs of all the forces involved.


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In the case, when = = 0 for all the existing shear walls, Eqs. (8.11) and (8.12) simplifyto

X =

Y =

e Shape ofshear

wall

lx ly Ay Ax Rx Ry Ror

J Position ofcentroid C

(CX,CY)

112

112 t

Lt Lt 0 0 0 Cx=Cy=0

12 + 6

2 + 3+2

4.3 CALCULATION OF SHEAR CENTRE:

Step 1: Evaluation of rigidity characteristics of shear walls.

As all the shear walls forming the structure are of same material, E is being omitted from all

expressions of rigidity characteristics.


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For A:

= L x t= 25 x 0.3

= 7.5 m

= 7.5 m= x L x =

x 25 x 0.3

= 0.056

= x x t=

x 25x 0.3

= 390.62=

.

=

..

.

Rigidity

= 0.683= 0= = 0Torsional rigidity

J= 0

Position of centroid

= = 0Shear center m = 0

Shear wall "B " resembles "A"


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Now for "C"= 10 x 0.3

= 3 m

= 3 m= x 0.3 x 10

= 25 = x 10 x 0.3

= 0.0225

= 0 =

.

=

.

= 0.22

Torsional rigidity

J = 0

Position of centroid ( , ) = 0Shear centre (m) = 0

Shear wall D resembles same as C

Summary of rigidity characteristics

Shear wall m JA 0.683 0 0 0 0 0B 0.683 0 0 0 0 0

C 0 0.22 0 0 0 0

D 0 0.22 0 0 0 0

Summation

() 1.366 0.44


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Step 2: Location of shear centre of the structure: Assuming the quantities required for location

Shearwall

Direction Direction

A 0.683 0 0 0 0 0 0 0 0 0 0 0

B 0.683 0 41 40 27032 0 0 0 41 40 0 0

C 0 0 15 0 0 0 0.22 0 15 0 3.3 0

D 0 0 40 -15 0 0 0.22 0 40 -15 8.8 0 1.366 0 - - 27.32 - 0.44 - - 0 12.1 0

axes () to be coincident with the shear center of the shear wall (A), the shear center ofstructure (, ), the various quantities required in the above equations being computed with thehelp of above table

x 1.366 - (0) = 27.32= 20x (0) (0.44) = 0 12.1= 27.5Therefore the value of the shear center is (27.5,20) for the college shear wall of fourth block

south east wall of G.R.I.E.T.


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4.4 Calculation of seismic and shear forces

BEHAVIOUR OF SHEAR WALLS:

The behavior of shear walls, with particular reference to their typical mode of failure is, as in the

case of beams, influenced by their proportions as well as their support conditions. Low shearwalls also known as squat walls, characterized by relatively small height-to length ratios, may be

expected to fail in shear just like deep beams. Shear walls occurring in high-rise buildings, on the

other hand, generally behave as vertical cantilever beams with their strength controlled by

flexure rather than by shear. Such walls are subjected to bending moments and shear originating

from lateral loads, and to axial compression caused by gravity. These may, therefore, be

designed in the same manner as regular flexural elements. When acting as a vertical cantilever

beam, the behavior of a shear wall which is properly reinforced for shear will be governed by the

yielding of the tension reinforcement located near the vertical edge of the wall and, to some

degree, by the vertical reinforcement disturbed along the central portion of wall.

It is thus evident that shear is critical for walls with relatively low height-to-length ratios and tall

shear walls are controlled mainly by flexural requirements particularly if only uniformly

distributed reinforcement is used. This is a typical shear wall of height , length, andthickness. It is assumed to be fixed at its base and loaded horizontally along its left edge.Vertical flexural reinforcement of area is provided at the left edge, with its centroid at adistance from the extreme compression face. To allow for reversal of load, identicalreinforcement is provided along the right edge. Horizontal reinforcement of area at spacingS2, as well as vertical reinforcement of area (Av) at spacing S1is provided as shear

reinforcement. Distribution of minimum reinforcement vertically and horizontally helps to

control the width of inclined cracks. Such distributed steel normally is placed in two layers,

parallel to both faces of the wall.

Since the ductility of a flexural member such as a tall shear wall can be significantly affected by

the maximum usable strain in the compression zone concrete, confinement at the ends of the

shear wall section would improve the performance of such shear walls. Such confinement can

take the form of enlarged boundary element with adequate confining reinforcement. In the

flanged wall sections, the adjacent parts of the wall will provide lateral support to each other.

Confinement may also be obtained from the presence of other walls running at right angles to the

shear wall at its ends. In both cases, the additional compression flanges contribute to the increase

in ductility. Shear wall sections are often thin and therefore, under reversed cyclic yielding there

is a danger of section instability. The wall-return may usually be necessary between the ground

and first floors of a building to increase stability.

It is also required that the vertical forces resulting from seismic loads are resisted entirely by the

boundary elements. It is similar to the design approach used in steel I-beams where flanges resist


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the flexural stresses and the web carries the entire shear. In shear walls of high-rise structures,

enough shear capacity is provided so that a shear failure does not precede a flexural failure.

However, a portion of a shear wall, which interacts with the frames, may behave as a low shear

wall, depending upon the proportions of the walls and the location of the point of contra flexure

along the height of the wall. The latter is dependent primarily on the relative stiffness of theframe and the shear wall elements in a structure.

TALL SHEAR WALLS:

In multi-storey buildings, the shear walls are slender enough and are idealized as cantilevers

fixed at base. Their seismic response is dominated by flexure. Because of local reversals, shear

wall sections necessarily contain substantial quantities of compression reinforcement. IS 1893:

2002 has laid down the procedure to assess the flexural and shear strengths of tall shear walls

and is described in the following subsections.

FLEXURAL STRENGTH:

In shear walls, particularly in areas not affected by earth quakes, the strength requirement for

flexural steel is not great. Traditionally, the practice is to provide about 0.25 per cent

reinforcement uniformly in both directions over the entire depth. Naturally, such an arrangement

does not efficiently utilize the steel at the ultimate moment because many bars operate on a

relatively small lever arm. Moreover, the ultimate curvature, hence the curvature ductility, is

considerably reduced and this arrangement is also uneconomical.

In an efficient shear wall section subjected to considerable moments, the bulk of the flexural

reinforcement is placed close to the tensile edge. Because of moment reversals originating from

lateral loads, equal amounts of reinforcement are normally required at both extremities. Thus, a

considerable part of bending moment can be resisted by the internal steel couple, and this will

result in improved ductility properties. The practice is to provide minimum reinforcement over

the inner 80 percent depth and allocate the remainder of the steel to outer zones of the section.

As shown by the theoretical moment-curvature relationship, this distribution of steel results in an

increase in the available strength and ductility.

To increase the ductility of cantilever shear walls at the base, where the overturning moments

and axial compression are the largest, the concrete in the compression zone must be confined.

The confining steel is provided in the same way as in tied columns and can be extended over the

part of the depth, where concrete strains in excess of 0.0035 are required. This is particularlyimportant over the region of a possible plastic hinge, which may extend over a full storey height

or more. The flexural strength of a slender rectangular shear wall section with uniformly

distributed vertical reinforcement and subjected to uniaxial bending and axial load may be

estimated as follows:


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Case 1:

For=

=

1+

0.416

0.168+

Where

=

.

=

.. .

= . , = =

, =

. .

Where is the depth of the neutral axis from extreme compression flange,is the balanced depthof neutral axis,

is the inclination of the diagonal reinforcement in the coupling beam,

is the soil-foundation factor (IS 1893: 2002),

is the vertical reinforcement ratio,

is the area of uniformly distributed vertical reinforcement,is the elastic modulus of steel, and

is the axial compression on the wall.

Case 2

For , the area of horizontal shear reinforcement,, ata vertical spacing, , can be determined from the expression= . Where is the shear force to be resisted by the horizontal reinforcement and is given by= (d) Uniformly distributed vertical reinforcement not less than the horizontal reinforcement

should be provided. This is particularly important for squat walls. When the height-to-width ratio


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is about 1.0, both the vertical and horizontal reinforcement are equally effective in resisting the

shear force.

FLEXURAL STRENGTH

The moment of resistance of short shear walls is calculated as for columns subjected tocombined bending and axial load. The procedure for the calculation of moment of resistance,

of tall rectangular shear walls is as describedFor walls without boundary elements, the vertical reinforcement is concentrated at the ends of

the walls. A minimum of four bars, 12mm , arranged in two layers, are provided at each end.

BOUNDARY CONDITIONS

There are the portions along the wall edges and may have the same or greater thickness than the

wall web. These are provided throughout the height with special confining reinforcement. Wall

sections having stiff and well confined boundary elements develop substantial flexural strength,

are less susceptible to lateral buckling and have better shear strength and ductility in comparison

to plane rectangular walls not having stiff and well-confined boundary elements.

(a) During a severe earthquake, the ends of a wall are subjected to high compressive and tensile

stresses. Hence, the concrete needs to be well confined so as to sustain the load reversals without

a large deterioration in strength. Thus, the boundary elements are provided along the vertical

boundaries of walls, when the extreme fibre compressive stress in the wall due to factored

gravity load plus factor earthquake force exceeds 0.2fck. The boundary element may be

discontinued where the calculated compressive stress becomes less than 0.15fck.

(b) The boundary element is assumed to be effective in resisting the design moment due to

earthquake induced forces, along with the web of the wall. The boundary element should have an

adequate axial load carrying capacity so as to carry an axial compression equal to the sum of the

factored gravity load plus compressive load due to seismic load. The latter may be calculated as

=

Where Mu is the factored design moment on the entire wall section, is the moment ofresistance provided by the distributed reinforcement across the wall section, and is the c/cdistance between the boundary elements along the two vertical edges of the wall.

(c) Moderate axial compression results in higher moment capacity of the wall. Hence, the

beneficial effect of axial compression by gravity loads should not be fully relied upon in a


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design, due to the possible reduction in its magnitude by vertical acceleration. When gravity

loads add to the strength of the wall, a load factor of 0.8 may be taken

(d) The percentage of vertical reinforcement in boundary elements should range between 0.8 and

6 percent.

(e) During a severe earthquake, boundary elements may be subjected to stress reversals. Hence,

they have to be confined adequately to sustain the cyclic loading without a large degradation in

strength. Therefore, these should be provided throughout their height.

(f) Boundary elements need not be provided if the entire wall section is provided with special

confining reinforcement.

4.5 Design the ductile shear wall for college building

A five storey building with plan dimensions as shown.

The height between floors is 4.0m

The dead load per unit area of the floor which consists of floor slab finishes is 4 KN/.Weight of partitions on floors is 2 KN/m

The intensity of live load acting is 3 KN/

on floor and on terrace 1.5 KN/

.

Loads are considered as per IS: 875, part1 and part 2.Grade of concrete being used M-30.

Grade of steel used is Fe 415.

Unit weight of reinforced concrete is 25 KN/.And Beams and Columns o cross section is 450x300mm and 600x300mm.

To calculate:

The seismic forces and shears at different floor levels.

Design the ductile shear wall to resist seismic forces.

Solution:


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Seismic weight of the building:

As per IS code 1893:2002 the percentage of design live load to be considered for the calculation

of earthquake. Force is 25% for the floors and no live load needs to be considered for roof.

Hence the effective weight of each floor = 4.0 + 2.0 + 0.25 x 4 = 7 KN/.And that of roof = 4 KN/.Self weight of 80 columns = 0.3 x 0.6 x 4 x 25 x 80 = 1440 KN

Weight of columns at roof = 1440 = 720

Weight of 140 beams = 0.45 x 0.300 x 5 x 140 x 25 = 2362.5

Plan area of building = (40 x 40.5) + (10 x 20) = 1820 Equivalent load at roof level = 4 x 1820 + 2362.5 + 720 = 10363.5 KN

Equivalent load at each floor = 6.75 x 1820 + 2362.5 + 1440 = 16087.5 KN

Seismic weight of building = 10363.5 + (16087.5 x 4) = 74713.5 KN

Base shear:

The fundamental natural period of vibration (T) for the buildings having shear walls is

T = . = . = 0.28

Building is situated in Hyderabad zone II.

As per zone factor (Z) = 0.10

Importance factor (I) = 1.5

Response reduction

Ductile shear wall with shear moment resistant frame (R) = 5

For 5% damping and type I soil

= 1.81

Design horizontal seismic coefficient


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= = . . . = 0.02715Base shear =x W = 0.02715 x 74713.5 = 2028.47Design lateral force at various floor levels. Design lateral force at floor i:

= Mass no.

1 10363.5 20 4145400 0.3493 708.54 708.54

2 16087.5 16 4118400 0.3470 703.9 1412.44

3 16087.5 12 2316600 0.195 395.5 1807.94

4 16087.5 8 1029600 0.0867 175.9 1983.84

5 16087.5 4 257400 0.0216 43.8 2027.64

= 11867400

Bending moment and shear force:

Two shear walls are provided as given in the problem to resist the seismic forces in each

direction

The shear wall is assumed to be cantilever in calculations.

Maximum shear force at base (V) = 1013.82 KN

Maximum bending moment at base

M = (21.4 x 4) + (87.95 x 8) (197.75 x 12) + (3510.95 x 16) (354.27 x 20) = 15878.8 KN. m

Taking partial safety factor = 1.5

Factored shear force () = 1.5 X 1013.82 = 1520.73Factored bending moment () = 15878.8 x 1.5 = 23818.2Considering axial load acting = 16000 KN

Factored axial load = 1.5 x 16000 = 24000 KN

Flexural strength of shear wall:

= 30 N / m = 415 N / m= 2.0 x 10N/ m


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Length of wall () = 24.4 mThickness of wall () = 0.3 mProviding uniformly distributed vertical reinforcement ratio

= 0.25%= .

=. .

= 0.030

= =

= 0.0728 = 0.109

=.

. =

.

. = 0.5158

=

.=

.. . .= 0.3309

=

.. .

=.

. . = 0.6597

67513.8 > 23818.2


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Balance moment to be resisted by the edge reinforcement in each shear wall

=23818.2+67513.8= 43695.6

Effective depth of wall = 0.9 = 0.9 x 24400 = 21960Area of steel =

. =

. . = 5511.09

Equal amount of reinforcement is provided on the vertical edges of the wall which will act like

the flanges of a steel beam.

Provide 20 numbers. 20 bars in two layers in the wall at each end.Provided at ends = 314.15 x 20 = 6283 mMinimum reinforcement is provided in the vertical direction for a length of wall

0.8 = 19520 mm.Minimum area of steel required in the shear wall

= 0.0025 x 24400 x 300 = 18300 mArea of minimum reinforcement per meter length of wall

= 0.0025 x 1000 x 300 = 750 m

Maximum permissible spacing = or 3 or 450.

=

= 7880

3 = 3 x 300 = 900Therefore spacing between reinforcement = 450 mm c/c.

Provide 10mm bars at 300 mm c/c in the vertical direction in two layers.Check for shear:

Factored shear force () = 1520.73 KNNominal shear stress =

=

. = 0.23 N/m

Permissible shear stress for M30 grade concrete and steel ratio,


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P = 0.25%

(As per clause 9.24 of IS: 13920 : 1993 )

If

Then

As per clause 9.15:

If the factored shear stress in the wall exceeds 0.25 or if the wall thickness exceeds 200 mmthen the reinforcement is provided in two directions. each having running in horizontal and

transverse directions.

The maximum spacing shall not be smaller than , 3and 450 mm = 450 mm

Thus the reinforcement provided in horizontal direction =

=.

= 349.06 mBut area of minimum reinforcement is 750 m.Hence provide minimum reinforcement of 0.25% of the gross area of the wall, in the horizontaldirection.

Provide 10 bars at 450 mm c/cThe detailing of shear wall


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FIGURE : 4.5.1 Detailing of reinforcement sectional elevation

FIGURE : 4.5.2 Detailing of reinforcement sectional plan.


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CHAPTER 5

DESIGN OF COLLEGE BUILDING USING E-TABS

Firstly click on the ETABS icon .A window appears which shows a different tip every time you

open the software.

This window provides us 3 options. You can click on previous or next tip to checkout some

more tips or else click ok to move further.

Change the units at the right bottom to KN-m or any other as per your convenience.

Click on file option to create a new file or to open an already existing file

When you open a new file another window appears which again contain 3 options

- choose. edb

- default. edb and

-no

Fig 5.01-New model selection

-First option helps us to select an already existing file

-Second helps us to create a new file and

-The third displays the grid data and story data

*As we are creating a new file, we click on default.edb


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*A new window appears which has Building plan grid system and Story data. In grid dimensions

we can either use uniform spacing or we can customize the grid spacing. We have to provide no

of lines in x and y directions as per the columns and beams used in the plan.

Fig 5.02-Provision of storey and grid data

*In the story dimensions, we have simple story data and custom story data. In simple story data,

use the defaults or specify values for the number of stories, typical story height, and bottom story

height. The value specified for the typical story height will be used for all stories in the model,

except the bottom story whereas in custom story data we can manually define story names, story

levels of non-uniform height, and story similarity.

*After providing the entire data click on grid only in structural objects and then click on ok.


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Fig 5.03-ETABS main window

*Now the screen is divided into two equal halves in which one is plan view and the other is 3-D

view of the provided data.

*We can change the view options to plan,3D or elevation views. We can select any of the stories

as per the work to be done on that particular story. At the right corner we change the story

options to either similar or all stories. This makes us to save time i.e. if we are working on a

particular story, then that is transferred to remaining stories or similar stories as per the option

selected. The top story is selected as default story.

*After the entire grid data and story data is provided, then we have to define the properties of the

material that is used.

*To define a material property, select define=>material properties. This makes us to either add

new material, modify or delete an existing material. Click on add new material to create a new

material with required properties.

*Firstly provide a name(say M20,M30 etc) and then provide the other properties of the material

such as mass per unit volume, weight per unit volume, elastic modulus, Poissons ratio. The

other design properties that are to be provided are characteristic compressive strength and yield

strength values. You have other options such as change in display colour, type of material which

is always isotropic. After the entire data is provided click on ok.


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*The next step is to create beams and columns. To create a beam or column, first we click on

define=>frame sections command to create a beam or column. In this window we have import

and add options further provided with modify or delete options of already existing properties.

Fig 5.04-Addition of frame sections

*There are many options in add such as add circle, steel joints and further more but we provide

rectangular columns or beams in common and hence we add a rectangular section and then click

on ok. Another window appears which gives details about section. Here we can provide section

name i.e., either a beam or column and change the material to the one that is defined above.

Provide the dimensions of the section as required and change the data according to the section

provided. If a beam is to be provided then select the design type to beam and provide therequired dimensions to the cover and if a column is provided select design type to column and

then nominal cover is provided.

5.1:Marking of columns, beams:

*To create a column, the above process is repeated again and the only difference is the

reinforcement data which is stated earlier both for beams and columns.


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Fig 5.1.1-Columns of the Civil block

*To assign a beam, we can directly click on the icon create lines or region at click. The other

way to do it is to click on Draw menu=>Draw line objects=>Create lines or regions at click

command. A window appears which provides properties of the object in which the property is

changed to the beam that we defined earlier. We can click on each grid point or directly select all

at once and the beams are assigned to the grid.


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Fig 5.1.2-Beams of the Civil block

Fig 5.1.3-Beams after they are assigned


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*To assign a column, we can click on create columns in region or at clicks or click on Draw

menu=>Draw line objects=>Create columns in region or at clicks. In this the property is changed

to the defined column and columns can be assigned to offsets in x and y directions. Columns are

also assigned in the similar way as beams are assigned.

Fig 5.1.4-Columns after they are assigned

5.2:Drawing floor area:

*Further we have to provide slabs for which we have to select define menu=>wall sections after

which a window appears with options add new, modify/show section and delete section. Click on

add new slab and click on ok. A new window appears where provide the section name as slaband the material is changed to the already defined one. The other data is kept as it is. We can

change the display colour to our convenience and then click ok.

*To assign a slab, directly click on the draw rectangular areas and the other is to click on Draw

menu=>Draw area objects=>draw rectangular areas. The properties of the object are changed to

the defined slab and then assigned to the end points of the grid. The slab can be made visible by


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a click on SetBuilding view options on the top and the option object fill is marked in special

effects options.

Fig 5.2.1-Building view options window

Fig 5.2.2-Slabs after they are assigned


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Fig 5.2.3-Slab view of the Civil block

*After the slab is assigned to the structure the next step is to provide the wall for the structure

which is the major portion of the construction as we are providing shear walls. Shear walls aredirectly provided as that of slab with the help of a special type of formwork using concrete.

There is no role of bricks in this kind of wall. There are some requirements for shear wall design

i.e., the minimum thickness of the shear wall should be 150 millimeter or more.

*Now for construction of a wall, firstly click define=>wall/slab/deck sections=>click to add new

wall=>name the wall and the material is selected as M30 and no more brick is used and then

click ok without changing any other information.

*To assign the wall, click directly on draw walls or create walls at click at the left side of screen

or select draw=>draw area objects=>draw walls or create walls at click and assign the walls at

the required places. To make the wall visible, click on SetBuilding options and the object fill is


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marked.

Fig 5.2.4-Walls of the Civil block


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Fig 5.2.5-Wall after it is assigned

5.3:Assigning of loads:

*After the columns, beams, walls and slabs are assigned now the loads are to be applied to the

structure. There are different load combinations used in this software. For shear walls, lateral

loads and seismic loads play a vital role.

*To assign any particular load, click Define=>Static load cases. In this window dead load and

live load are already assigned. To assign any other loads change the name of the load in load

option, select the load type in type option, add the self weight multiplier as required. The auto

lateral load options provide different code books that are used across the world. We use IS 1893

2002 code.


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Fig 5.3.1-Defining Static loads

*After we have defined the loads that are required to be provided for the structure, now the loads

are need to be assigned. For the loads that are acting on beams, select all the beams and then

click assign=>frame/line loads =>distributed=>select the load that is to be to assigned and then

click ok.


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Fig 5.3.2-Frame/Line loads after they are assigned

*For slabs and walls, select all the walls and slabs and then click on assign=>shell/area

loads=>uniform. Select the load that is to be assigned and then click ok.


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Fig 5.3.3-Shell/Area loads after they are assigned

*To check whether the loads are assigned or not, click display=>show loads=>select joint/point

or frame/line or shell/area=>select the load that you need to check in load case and then click ok.The load is displayed in the plan view at the centre.

*There are several load combinations that can also be designed depending on the requirements

by selecting define=>load combinations and then we can add numerous combinations as per the

given code.


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*The additional loads that are to be defined are seismic and lateral loads for shear wall design.

Hence quake and wind loads are defined in both x and y directions and then they are assigned to

the structure.

Fig 5.3.4-Different loads defined

5.4:Analysis:


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CHAPTER 6

CONSTRUCTION OF SHEAR WALLS

6.1: Excavation:

After the initial surveying and soil test, excavation of land is carried out. If the land site is

very hard with rocks and boulders, excavation is carried out using heavy earthquakes, cranes

and diggers. And in some cases if the land is very hard, blasting of site by using small amount

of dynamites is preferred. Generally blasting of site is done during early mornings.

Fig 6.1.1-Excavation using heavy earth movers.

Once the excavation is completely done the excavated material is not wasted. It should be

generally reused in the same construction work so that construction work is reduced.

On the other side, if the land is very loose and site is being excavated very easily then earth

movers of normal size are used.


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Fig 6.1.2-DRILLING

Once the excavation is completed marking of land for footings is carried out.

6.2: Foundation and Footings:

Generally shear walls are opted for tall buildings which are more than 15 floors so that they

can resist lateral load most effectively.

Therefore for this type of buildings we need strong foundation, so that it can resist high loads dueto self weight as well as lateral loads.

Hence combined footings and isolated footings are generally preferred.


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Fig 6.3.1-Columns beneath shear wall

Fig 6.3.2-Beams beneath shear wall


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Now if the building requires parking, the bottom two to three floors are built with heavy beams

and columns of dimensions (0.9 x 0.3) m and (0.45 x 0.3) m.

Waffle slab:

The slab here should be of high load bearing as it needs to bare the vehicles load as well as the

top floor loads.

Hence for this situation waffle slab is most preferred.

Fig 6.3.3-Waffle slab layout

Waffle slab is a kind of slab which is of thickness 40 45 cm. But mostly empty with spacing as

of waffles.

The placing of the waffles is quite peculiar.

A form is placed and on above the waffles are arranged, once the arrangement is done,reinforcement is arranged in such a way that it forms a chess board and the squares are hollow

and the area with lines act as beams.


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Fig 6.3.4-Formwork for waffle slab

The waffle slab after curing looks like a normal slab from top but from the lower or bottom side

it chess board with hollow spacings.

Fig 6.3.5- Cured upper portion of waffle slab


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Fig 6.3.6-Lower view of waffle slab

Once the parking and waffle slab is completely laid then it comes the part of shear walls.

6.4: Shear Wall Construction:

Shear Walls:

Shear walls are generally casted monolithically, in this type of construction the beams and

columns are placed inside the walls so that you can never find beams inside any floor in this type

of construction.

Schedule of reinforcements:


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After the horizontal reinforcement is placed in accordance with the design, vertical

reinforcement is placed.

Fig 6.4.1-Horizontal reinforcement of shear wall

As per the design details the reinforcement of size 10mm spacing 30mm is placed in the middle

of the wall of length 0.8 = 0.8 x 25 = 200 m and the edge reinforcement of 20 mm 20 bars areplaced in the remaining 0.2 space.The horizontal bars on the vertical reinforcement are placed of diameter 10 mm spacing 300 mm

distance.


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Fig 6.4.2-Vertical Reinforcement of shear wall

This reinforcement in the horizontal direction is usually tied as double strand single tie with GI

wire, this process can also be done by using rebar machine.

Normally cover either cement or most preferably PVC cover is tied to the vertical reinforcement

so that once form work is place it maintains a specific cover distance.

Once the reinforcement is completely placed then comes the part of Mivan form work.

6.5: MIVAN FORM WORK:

MIVAN is an upcoming technology which has empowered and motivated the mass

construction projects throughout the world. Good quality construction should not reduce the

project speed nor should it be uneconomical.

Construction is done through MIVAN technology keeping a motto in mind that Cost is long

forgotten, but the Quality is remembered forever


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Mivan is an aluminium formwork system developed by a European construction company. In

1990, the Mivan Company Ltd. from Malaysia started manufacturing these formwork systems.

Today, more than 30,000sqm of formwork from Mivan Co. Ltd. is used across the world. There

are a number of buildings in Mumbai that are being constructed with the help of the Mivan

system, that has proven economical as well as satisfactory for the overall Indian constructionenvironment. One of the architectural examples is XRBIA which uses MIVAN system to achieve

its dream of A House for Every Indian

Fig 6.5.1-MIVAN formwork

MIVAN technology is suitable for constructing large number of houses in a short span of timeusing room size forms to construct walls and slabs in one continuous pour on concrete. In this

system of formwork construction, castinsitu concrete wall and floor slabs cast monolithic

provides the structural system in one continuous pour. To facilitate fast construction, early

removal of forms can be achieved by hot air curing / curing compounds. Large room sized forms

for walls and floor slabs are erected at site. These strong and sturdy forms are fabricated with


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accuracy and are easy to handle. The concrete is produced in RMC batching plants under strict

quality control and convey it to site with transit mixers.

The frames for windows, doors and ducts for services are placed in the form before concreting.

Staircase flights, panels, chajjas and jails etc. and other pre-fabricated items are also integrated

into the structure. This proves to be a major advantage as compared to other modern constructiontechniques. High quality Mivan Formwork panels ensure consistency of dimensions. On the

removal of the formwork mould a high quality concrete finish is produced to accurate tolerances

and verticality. The high tolerance of the finish means that, no further plastering is required.


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Fig 6.5.2-Alluminium panels of MIVAN formwork


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Uses of Mivan Formwork:

3S System of Construction Speed, Strength, Safety Column and beam construction are eliminated Walls and slabs are cast in one operation Specially designed, easy to handle light weight pre-engineered aluminium forms Fitting and erecting the portion of shuttering Carrying out concreting of the walls and slabs together

Advantages:

Mivan formwork requires relatively less labour More seismic resistance Increased durability Lesser number of joints and reduced leakages Smooth finishing of wall and slab Uniform quality of construction Negligible maintenance Faster completion

Limitations:

Even though there are so many advantages of Mivan formwork the limitations cannot be ignored.

However the limitations do not pose any serious problems. They are as follows: -

Because of few small sizes finishing lines are seen on the concrete surfaces Services after completing become slightly difficult due to the small width of components It requires uniform planning as well as uniform elevations to be cost effective The formwork requires number of spacer, wall ties etc. These produce problems such asseepage, leakages during monsoon

Due to box-type construction, contraction cracks are likely to appear Heat of hydration is high due to shear walls It is rigid in design once placed, as any alteration becomes tough later

Remedial Measures:

It is possible to minimize contraction cracks by providing control strips in the structure which

could be concreted with a delay of about 3-7 days after major concreting. The problem of

cracking can be avoided by minimizing the heat of hydration.

Once the mivan panels are placed carefully they are tied generally by using wall ties pins and

wedges.


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6.6: Wall ties, Pins and Wedges:

Wall Ties:

Fig 6.6.1-Wall ties

Wall ties are thin plates of dimensions 20 cm x 4.5 cm x 0.3 cm with three holes of diameter

12mm on either side.

Wall ties are generally used to tie the form work. Wall ties are so placed from inside the form

work.

Form work when once placed is tied together with the wall ties filled with grease and plastic

cover is winded over the central portion of the wall tie.

Once this arrangement is made the holes of wall tie and the holes of form work are made to

coincide and filled using pins and wedges.

Pins and Wedges:

Pins actually resemble the rivets its top diameter of head is 12 mm and its tail is about (6-8) mm

with a rectangular hole in it of 2 mm thickness.


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Fig 6.6.2-Pins and Wedges

Wedge is of thin iron sheet mostly resembles the front view of frustum of cone.

Its top size is 2 cm and base is of 1 cm.

Once the form is completely placed with wall ties coinciding the holes, pin is placed and wedges

are drilled with the help of a wooden hammer.

Wall ties with grease and yellow cover finds its importance after concreting.

This eases the work of removal of wall ties.

Once the concreting is done and cured wall ties are carefully removed by pulling them out. The

cover which is placed on the central portion of the wall tie remains inside the wall and the gap

which remains is filled with cement mortar.

6.7: Electrical boards and Plumbing lines:

The shear walls in a building itself acts like column with no flexibility to drill and hence it

becomes very important to place electrical lines and plumbing or sewer lines.


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Fig 6.7.1-Electrical lines in slab

The electrical lines in slabs and wall also have a design.

Fig 6.7.2-Gaps left for plumbing lines

The plumber and sewer lines are left with gap to place into the wall exactly.


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Fig 6.9.1-Shear wall after removal of formwork

Firstly the wedge is taken out by using a hammer and then pin is also removed.

Now started from top and one side form is carefully removed.

The form removed is cleaned immediately, to remove the concrete on it, so that it can be reused

effectively.

Once the form is completely removed a smooth finish of wall is obtained which does not requireany plastering.

The wall which is now finished with the removal of form is cured with regular water i.e water

which we use for drinking purpose.

Curing of walls is done for 3 7 days continuously and for better curing and to reduce heat of

hydration a white coating with lime powder is also preferred.

Curing can also be done by covering walls with plastic covers and watering them so that it

reduces the heat of hydration.

6.10: Holes in the slab:

There are rectangular holes in the slab left out to carry form work from bottom storey to top.


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As it becomes difficult to take form work through staircase for constructing the next floor, these

holes are drilled in the slab of size a little more than the standard form work.

Fig 6.10.1-Holes drilled in the slab

Hence these holes play a key hole in transfer of mivan form work.

6.11: Electrical and Plumbing lines after concreting:

After the walls are completely built they are checked for electrical and plumbingconnections.

As electrical lines are pre-established with design pattern in the slab as well in the wall only

thing needed is to arrange them with proper connection.


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Fig 6.11.1-Electrical spaces left in wall

When it comes to the server lines holes or empty gaps are left over. And in these empty spaces

the sewer pipes are placed exactly to match the empty spaces.

Fig 6.11.2-Gaps left for sewer pipes

In this way electrical and plumbing lines are placed.


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6.12: Painting and Finishing Works:

As the wall which is obtained is perfectly plain with exact finishes there is no need for and

plastering work.

Fig 6.12.1-Painting and finishing works

design & construction of shear wall

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