EFFECT OF COLUMN, BEAM SHAPE AND SHEAR WALL ON STOREY DRIFT

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CHAPTER I
INTRODUCTION
1.1 General
On the most basic level, structures are designed for strength (safety) and
serviceability (performance). Serviceability issues include deflection, vibration
and corrosion but with respect to wind the issue of concern is storey drift of
structure.
Drift is the lateral displacement of one level of a multi-storey structure relative
to the level above or below due to lateral loads. Lateral loads are mainly
responsible for drift. Due to lateral loads there will be a drift or sway on the
high rise structures and it is the magnitude of displacement at the top of a
building relative to its base. For a high rise building shear wall system is
superior for resisting lateral loads.
Shear wall is a wall composed of shear panels to counter the gravity loads and
also lateral load performing on a structure. Shear wall is concrete or masonry
continuous vertical walls may serve both architecturally as partitions and
structurally to carry gravity and lateral loading. Frame structure is the rigid
joint structure between an assemblage of linear elements to from vertical and
horizontal planes.
The vertical planes consist of columns and girders mostly on rectangular grid, a
similar organizational grid is used for horizontal planes consisting of beam and
girders. In the high rise building flat slab is a typical type of construction in
which a reinforcement concrete slab with or without drops is built
monolithically with the supporting column and is reinforcement in two or more
direction without any provision of beam, the flat slab thus transfers the load
directly to the supporting columns suitably spaced below the slab. Unwarranted
lateral displacements can create severe structural troubles.

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High rise structure should be capable for resisting any type of lateral loads as
well as gravity and live loads. Sustainability and expected service life is the
very important matter to consider the design process of high-rise structures.
1.2 Project Objective and Possible Outcomes
The major purpose of this thesis is to incorporate the effects of column shape
(with shear wall & without shear wall) & effects of moment of inertia of beams
(with shear wall & without shear wall) on storey drift.
The objective of the response also includes the following-
 To study the performance of column shape with shear wall &
without shear wall on storey drift.
 To study the effects of beams with shear wall & without shear wall
on storey drift.
 To carry out a limited parametric study to observe the effects of
different geometric column shape and beam size on performance of
the structure.
Possible outcomes of the thesis thus include-
 The comparison among the performance of the structure with shear
wall & without shear wall under varying column shapes and beam
sizes.
1.3 Thesis Organization and Outline
This thesis consists of five chapters. These describe all the respective steps and
the plans according to following outlines

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 Chapter 1 – Introduction: In this chapter, a brief introduction of the
thesis its objectives possible outcomes and a basic outlines of the
thesis are described.

 Chapter 2 – Literature Review: This chapter presents a literature
review for wind load and shear wall and methodology for load
analysis.

 Chapter 3 – Methodology: In this chapter the modeling of building
are presented and analysis of that models by ETABS v9.7.4 software

 Chapter 4 – Results and Discussion: This chapter presents the
analytical results for changing different geometric parameter of
beams and columns of the test building.

 Chapter 5 – Conclusions and Recommendations: this chapter
summaries the findings of this research, presents its conclusions and
makes recommendations for safeguarding buildings against wind
loads and for further academic research.
1.4 A Brief Historyof Wind and Structures
Engineers have always realized that wind can affect structures. The French
structural engineer Alexander Gustave Eiffel recognized the effects of wind
when he designed the Eiffel Tower. At 986 feet, the Eiffel Tower was the
tallest structure in the world from 1889 until 1931, when it was surpassed by
the Empire State Building. In the design of the Eiffel Tower the curve of the
base pylons was precisely calculated for an assumed wind loading distribution
so that the bending and shearing forces of the wind were progressively
transformed into forces of compression, which the bents could withstand more
effectively (Mills 2007).
For advancements to come about in any field, it is usually true that there must
be some sort of impetus for change; factors that spur new ideas and solutions.

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Economic factors drive many facets of our everyday life and this is especially
true for the field of Structural Engineering. The need to build higher,
particularly in dense urban areas, brought about advancements in engineering
and construction techniques that saw the skyscraper boom of the 1920’s and
30’s and the revival in the 1960’s. Building big meant spending big and
subsequent advancements were made in the form of lighter, stronger materials.
In turn, building large and light led to lightly damped and more flexible
structures. Consequently wind was suddenly an important issue in the design of
structures.
There are three important structural failures involving wind that deserve
mention here. They are important milestones in the advancing art of designing
for wind and will be presented in the order in which they occurred. Attention to
wind was first brought to the forefront of the field in 1940 when Washington
State’s Tacoma Narrows Bridge collapsed under moderate, 40 mph winds. This
is quite possibly the most well-known example of the effects of wind on a large
structure. Failure was caused by inattention to the vibratory nature of the
structure; the low yet sustained winds caused the bridge to oscillate at its
natural frequency, increasing in amplitude until collapse. Wind tunnel tests
were suggested and implemented for the subsequent bridge design (Scott
2001).
The second failure involved the 1965 failure of three, out of a total of eight,
400-foot reinforced concrete cooling towers. Located in England, the failure of
the Ferry bridge cooling towers demonstrated the dynamic effects of wind at a
time when most designs considered wind loading as quasi-static (Richards
1966). However, wind is gusty and these peaks in the flow must be designed
for, not simply the average, especially when the structure is inherently flexible.
The towers failed under the strong wind gusts when the wind load tension
overcame the dead load compression. It has also been suggested by Armitt

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(1980) that the wind loading was magnified by the interference effects of the
surrounding towers.
The third example involves Boston’s John Hancock Tower. In early 1973 the
John Hancock tower experienced 75 mph winds that were believed to cause
over 65,000 pounds of double plane windows to crash to the sidewalks below.
Due to an agreement between the involved parties nobody knows the exact
reason why the windows failed, although it is widely speculated that the
problems were due to a window design defect (Campbell 1996). In addition to
the cladding issues the Tower swayed excessively in moderate winds, causing
discomfort for occupants of the upper floors. The unacceptable motion was
solved by installing two 300 ton tuned mass dampers, which had just been
invented for the Citicorp Tower in New York (LeMessurier 1993). Additional
lateral bracing was also added in the central core (at cost of $5 million) after it
was determined that the building was susceptible to failure under heavy winds
(Campbell 1996, Sutro 2000).
It is interesting to note that prior to construction of the John Hancock Tower,
wind tunnel tests on the design were conducted in a less expensive aeronautical
wind tunnel, as opposed to a boundary layer wind tunnel, and the results did
not indicate any problems. The importance of modeling for the boundary layer,
in which terrain, gustiness and surrounding structures all come into play, was
suddenly obvious; the overall behavior and interaction of wind and structures
was becoming apparent to the structural engineering community. With proper
wind tunnel testing, the John Hancock Tower may have avoided costly
retrofitting.
New York City’s World Trade Centre towers and Chicago’s Sears Tower were
among the first to fully exploit the developing wind tunnel technology. Built
during the second skyscraper boom these buildings and others fully exploited
all available resources and technological advancements. Boundary layer tests
were conducted that allowed the designers to optimize the structural system for

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displacements, accelerations and to design the cladding for wind pressures as
well. Technology continues to charge ahead and today’s wind tunnel tests are
more accurate and less expensive than ever before. For example, the pressure
transducers used in wind tunnel tests are much less expensive; they have
dropped in price from over a thousand dollars a piece in the 1970’s to thirty or
forty dollars today (Sutra 2000). Thanks to lower prices and faster computers,
wind tunnel experts now get real-time wind tunnel data from 500 or more
transducers, a vast improvement over the 8 or 16 typical in the 1970’s.
Throughout the years innovations have been made in how structures are
designed for the effects of winds loads, how wind loads are determined and
applied, and how the limits of wind loads are defined and utilized. In a way,
technology has both created and has helped to solve the problems related to
wind effects on structures. As new materials, both stronger and lighter than
predecessors, have been developed new problems have been encountered. The
use of lighter concretes, composite floors and stronger structural steel has
resulted in less damping and less stiffness. Less damping results in more
motion (acceleration) and less stiffness results in greater lateral displacements.
The importance of designing for wind has never been more apparent or more
important.

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CHAPTER II
LITERATURE REVIEW
2.1 Introduction
This review of the literature covers three main topics: Drift Limits, Modeling
and Analysis for Drift Design and Wind Loads.
The purpose of the literature review is to cover material related to wind drift
from the perspective of damage of non-structural components, modeling and
analysis and the appropriate wind loads. Covering the issues in this way is
crucial to establish that wind drift is a multi-dimensional issue that is dependent
on many variables. In effect, the literature review is conducted with the
intention of suggesting and establishing a comprehensive, performance based
approach to the wind drift design of concrete buildings.
2.2 Drift and Damageability
Drift is defined as the lateral displacement. Storey drift is the drift of one level
of a multi-storey building relative to the level below. Inter-storey drift is the
difference between the roof and floor displacements of any given storey as the
building sways, normalized by the storey height.
Drift limits are imposed for two reasons: to limit second order effects and to
control damage to non-structural components. Limiting second order effects is
necessary from a strength perspective while controlling damage to non-
structural components is a serviceability consideration.
For serviceability issues several topics need to be discussed: the definition of
damage, drift/damage limits to be imposed and the appropriate return interval
to use when calculating wind loads.

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Equation 2.1 defines the drift index.
Drift index = displacement/height ………………….(2.1)
Referring to Figure 2.1, a total drift index (Equation 2.2) and an interstorey
drift index (Equation 2.3) can be defined as such:
Total Drift Index = Total Drift/Building Height = ∆/H……………….. (2.2)
Interstorey Drift Index = Interstorey Drift/Storey Height= Δ/H……… (2.3)
Figure 2.1: Drift Measurement.
To limit non-structural damage, these drift indices are limited to certain values
to be discussed in the next section. Using drift indices is a straightforward,
simple way to limit damage. However, three shortcomings are apparent in
using drift indices as a measure of building damageability: One, it
oversimplifies the structural performance by judging the entire building on a
single value of lateral drift. Two, any torsional component of deflection and
material damage is ignored. Three, drift as traditionally defined only accounts

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for horizontal movement or horizontal racking and vertical racking is ignored.
The true measure of damage in a material is the shear strain which is a
combination of horizontal and vertical racking. If one considers that the shear
strain in the damageable material is the realistic parameter to limit, then it is
seen that drift indices are not always sufficient.
2.3 Shear Wall
In structural engineering, a shear wall is a structural system composed of
braced panels (also known as shear panels) to counter the effects of lateral load
acting on a structure. Wind and seismic loads are the most common loads that
shear walls are designed to carry. Under several building codes, including the
International Building Code (where it is called a braced wall line) and Uniform
Building Code, all exterior wall lines in wood or steel frame construction must
be braced. Depending on the size of the building some interior walls must be
braced as well.
Figure 2.2: Structure with shear wall.

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2.3.1 Advantages of Shear Wall
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 and wind forces, the overturning effects on them are large.
2.4 WIND LOADS
Wind loads are randomly applied dynamic loads. The positive or negative
force of the wind acting on a structure, wind applies a positive pressure on the
windward side of buildings and a negative suction to the leeward side.
The intensity of the wind pressure on the surface of a structure depends on the
wind velocity, air density, orientation of the structure, area of contact surface
and shape of the structure. Because of the complexity involved in defining both
the dynamic wind load and the behavior of an indeterminate RCC structure
when subjected to wind loads, the design criteria adopted by building codes
and standard have been based on the application of an equivalent static wind
pressure.
2.4.1 Definitions
Basic Wind Speed, V:
Three‐second gust speed at 10 m above the ground in Exposure B having a
return period of 50 years.
Building Enclosed:
A building that does not comply with the requirements for open or partially
enclosed buildings.
Building Envelope:
Cladding, roofing, exterior walls, glazing, door assemblies, window
assemblies, skylight assemblies, and other components enclosing the building.

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Building Low Rise:
Enclosed or partially enclosed buildings that comply with the following
conditions:
1. Mean roof height h less than or equal to 18.3 m.
2. Mean roof height h does not exceed least horizontal dimension
Building Open:
A building having each wall at least 80 percent open. This condition is
expressed for each wall by the equation Ao ≥ 0.8Ag where
Ao = Total area of openings in a wall that receives positive external pressure
zzzzz(m2).
Ag = The gross area of that wall in which Ao is identified (m2).
Building Partially Enclosed:
A building that complies with both of the following conditions:
1. The total area of openings in a wall that receives positive external pressure
exceeds the sum of the areas of openings in the balance of the building
envelope (walls and roof) by more than 10 percent.
2. The total area of openings in a wall that receives positive external pressure
exceeds 0.37m
Or 1 percent of the area of that wall, whichever is smaller, and the
percentage of opening s in
The balance of the building envelope does not exceed 20 percent.
These conditions are expressed by the following equations:
1. Ao > 1.10Aoi
2. Ao > 0.37 m2 or > 0.01Ag, whichever is smaller, and Aoi /Agi ≤ 0.20
Where
Ao, Ag are as defined for Open Building
Aoi = the sum of the areas of openings in the building envelope (walls and
roof) not incl uding Ao, in m2

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Agi = the sum of the gross surface areas of the building envelope (walls and
roof) not including Ag, in m2
Design Force, F:
Equivalent static force to be used in the determination of wind loads for open
buildings and other structures.
Design Pressure, P:
Equivalent static pressure to be used in the determination of wind loads for
buildings.
Eave Height:
The distance from the ground surface adjacent to the building to the roof
eave line at a particular wall. If the height of the eave varies along the wall,
the average height shall be used.
Effective Wind Area, A:
The area used to determine GCp. For component and cladding elements, the
effective win d is the span length multiplied by an effective width that need not
be less than one third the span length. For cladding fasteners, the effective
wind area shall not be greater than the area that is tributary to an individual
fastener.
Escarpment:
Also known as scarp, with respect to topographic effects in cliff or steep slope
generally separating two levels or gently sloping areas.
Free Roof:
Roof (monoslope, pitched, or troughed) in an open building with no enclosing
walls unde rneath the roof surface.

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Hill:
With respect to topographic effects in a land surface characterized by strong
relief in any horizontal direction.
Importance Factor, I:
A factor that accounts for the degree of hazard to human life and damage to
property.
Mean Roof Height, h:
The average of the roof eave height and the height to the highest point on the
roof surface, except that, for roof angles of less than or equal to 10degree, the
mean roof height shall be the roof heave height.
2.4.2 Methods
There are several methods, each with relative advantages and
disadvantages, currently available to determine wind loads on a
structure:
 Appropriate Codes And Specifications
 Boundary Layer Wind Tunnel Testing
 Database Assisted Design (Dad)
 Computational Aerodynamics
2.4.3 Factors Affecting Wind Loads
The following factors (Charney 1990) which affect design wind loads:
1. The wind velocity, which is a function of the recurrence
interval and the geographic location.
2. Topography and roughness of the surrounding terrain.
3. Variation in wind speed with the wind direction (directionality
factors)
4. The buildings dynamic characteristics
5. The buildings shape
6. Shielding effects from adjacent buildings.

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2.4.3.1 Wind Velocity
There are several methods of measuring average wind speed including the
fastest mile (the time it takes for one mile of air to pass), the mean hourly
(average wind speed over one hour), the 3 second gust (average wind speed
over a 3 second period) and others. Prior to ASCE 7-95 the wind velocities
were based on the fastest mile wind speed, a measurement that the National
Weather Service discontinued in favour of the 3 second peak gusts. To
convert from the ASCE 7-93 wind map, which provided fastest-mile
speeds, to the new peak 3 second gusts map, a study was undertaken in
which a conversion factor of 1.2 was deemed reasonable (CPWE, 1994, p.
7). The study which produced this conversion factor has been called into
question by Simiu et al. (2003) who points out several reasons why the new
3 second gust speeds can cause overestimation or underestimation of the
wind load, depending on the location. It is pointed out that the study was
not widespread enough to produce reliable data, especially for hurricane
prone areas.
2.4.3.2 Topography and Roughness of the Surrounding Terrain
The influence of terrain topography is site dependent and requires
engineering judgment. Most analytical and simplified techniques employ
the use of a topographic exposure factor which is applied to the wind
pressure to account for the effects of surrounding terrain.
Wind tunnels, through scale modeling of the surroundings, are able to better
account for these effects and in turn produce more accurate results.
2.4.3.3 Wind Directionality
Wind loads are calculated based on the assumption that the wind is blowing at
a right angle to the building face, regardless of the site specific wind
characteristics. This conservative approach has led to the development of the
wind directionality factor (Davenport 1977, Ellingwood et al. 1980).

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This factor accounts for two effects; (1) The reduced probability of maximum
winds coming from any given direction (2) the reduced probability of the
maximum pressure coefficient occurring for any given wind direction (ASCE
7-05).
It is important to note when the wind directionality factor is applicable in
calculating wind loads and the following discussion pertains to ASCE 7. There
has always been a wind directionality factor (designated as Kd) but prior to
ASCE 7-98 it was included in the load factor of 1.3 that is applied to wind in
the strength loading combination. Currently the wind directionality factor,
which can only be used in the strength loading combinations, has been
separated from the load factor of 1.3 which is why the load factor is now 1.6.
For the great majority of buildings the wind directionality factor is 0.85 and
0.85*1.6=1.36, which is nearly the same load factor as before.
2.4.3.4 Buildings Dynamic Characteristics
The rigidity of a building in the along-wind direction affects the loads that it
experiences. A very rigid building will not move much in the wind and the
effect of wind gusts magnifying the building motion is negligible, leading to a
simplified analytical expression for wind pressures. For flexible structures the
load magnification effect caused by gusts in resonance with along-wind
vibrations is more apparent and needs to be taken into account when
calculating wind pressures. Again, analytical techniques tend to be
conservative and wind tunnel testing, depending on the model used, can
provide more accurate results

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2.4.3.5 Building Shape
The physical shape of a building greatly affects the structural-wind interaction,
especially the torsional component of response. Specifications tend to be very
conservative regarding the influence of building shape and for irregular, tall or
slender buildings wind tunnel testing is highly recommended. For low-rise and
commonly constructed buildings the most significant effect of the building
shape is points of high cladding pressures and possible channeling effects on
pedestrians.
2.4.3.6 Shielding Effects from Adjacent Buildings
In a heavily built-up urban environment the wind loads a building experience
are heavily dependent on the surrounding buildings. These surrounding
buildings may either shield the building completely or channel wind directly
onto the building. The influence can be substantial, as demonstrated in a
lawsuit filed in the 1970’s by the owners of several buildings in the vicinity of
the World Trade Centre Towers in New York who claimed their buildings
were experiencing “unusual, increased and unnatural wind pressures” (Kwok
1989) due to the newly constructed Towers.
2.5 Gust Effect Factor for RigidStructure
For rigid structure the gust-effect factor shall be taken as 0.85 or calculated by
the formula given in BNBC as below:
G = 0.925
1+1.7gQIzQ
1+1.7gvIz
……………………………………. (2.4)

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Iz = c(
10
z
)
1
6 …………………………………………(2.5)
Where
Iz = Intensity of turbulence at height z
Z = equivalent height of the structure defined as 0.6h
Q = √
1
1+0.63 (
B+h
Lz
)0.63
…………………………. (2.6)
2.6 Methodology
2.6.1 Lateral deformation of rigidframe due to bending of beam and
column:
A significant portion of drift in rigid frames is caused by end rotations of
beams and columns due to lateral loads. This phenomenon is commonly
referred to as bent action. The lateral displacements of moment resistant frames
can be determined by the simplified approximate methods which are as
follows:
∆ =
(∑V)i (hi)²
12E
[
1
(∑kg)i
+
1
(∑kc)i
] ……………………………(2.7)
Here,
∆ = drift or deflection
E= modulus of elasticity of concrete
V= lateral load
h =storey height.
Ic= moment of inertia of column
Ig= moment of inertia of beam
Lc=column height
Lg=girder span.

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Kc = Ic/ Lc [for column]
Kg = Ig/ Lg [for beam]
i = storey level
This formula was used to calculate lateral deformation rigid frame
structure (beam slab building).
2.6.2 Lateral deformation of rigidframe due to bending of beam, column
and shear wall
Drift ∆ =
1
0.35
x
X R Kj
(εc + εy)L²
3(2X−j2
+j)d
……………………………….(2.8)
Simplifying equation are following:
Drift ∆ =
1
0.35
X
L² (2N+1)(εc + εy)
18 (d)
…………………………… (2.9)
Here,
∆ = deflection
εc = crete yield strain, considering value =0.003
εy = steel yield strain, considering value =0.00207 L = storey height
D=Depth of shear wall, 0.90h
N= number of storey
X=degree of freedom
K=stiffness of one storey
R=coefficient due to lateral load
2.6.3 Drift limitationaccording to BNBC
Storey drift is the displacement of one level relative to the level above or below
due the design lateral forces. According to BNBC code drift limitation is:
i) ∆ ≤ 0.0025h
ii) ∆ ≤ 0.04h/R ≤ 0.005h for T< 0.70 second.

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iii) ∆ ≤ 0.03h/R ≤ 0.004h for T ≥ 0.70 second.
iv) ∆ ≤ 0.0025 ( for unreinforced masonry structure)
Where, h= height of the building or structure.
The period T used in this calculation shall be the same as the base shear.
The allowable stores drift for stabilityof building is given below:
Table 2.1: The allowable storeys drift for stability of building.
Building Type Occupancy category
I or II III IV
Building, other than
masonry shear wall or
masonry wall or masonry
wall frame building, four
stories or less in height
with interior walls,
partitions, ceilings and
exterior wall systems that
have been designed to
accommodate the storey
drifts
0.025 hsx 0.020 hsx 0.015 hsx
Masonry cantilever shear
wall building
0.010 hsx 0.010 hsx 0.010 hsx
Other Masonry cantilever
shear wall building
0.007 hsx 0.007 hsx 0.007 hsx
All other buildings 0.020 hsx 0.015 hsx 0.010 hsx
** hsx = the storey height below level x

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CHAPTER III
METHODOLOGY
3.1 Overview
Present day computers and software are powerful tools for the design engineer
but require accurate input to produce reliable results. For a given structure
there are a number of assumptions regarding structural modeling that affect the
building’s lateral stiffness. Many of these assumptions, such as included
sources of deformation, beam column joint modeling, composite action, non-
structural components and second order effects were discussed in the literature
review.
This chapter aims to illustrate some of these assumptions and their resulting
effects on a given building’s lateral response under a ten year MRI wind load.
The structural system of the analytical building is discussed first, along with
the design of the gravity and lateral load resisting system. Next the lateral loads
are calculated based on Method 2 of ASCE 7-05, the Analytical Method. The
wind loads are determined for both strength (a 50 year MRI wind, with
applicable load factor) and serviceability (a 10 year MRI wind, with no load
factor). Finally the analytical models are presented. Points of comparison
between the models are made based on displacement vs. height and the periods
of the first six modes. Observations are made and the relative merits of each
model are examined.
3.2 Test Building: Structural System
Location: Dhaka City
The hypothetical building that was modeled is a rectangular (60 ft by 100 ft
plan dimensions) ten-storey RCC building with one lift core.

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First we analyses the structure with varying column size 18”x18”, 15”x22” &
12”x27” and keeping beam size constant 12”x21” for both with shear wall and
without shear wall.
Here we increase moment of inertia of column by keeping area constant.
Similarly we analyses the structure with varying beam size 12”x21”, 12”x24”
& 12”x27” and keeping column size constant 15”x22” for both with shear wall
and without shear wall.
3.3 Computer Software
ETABS Version v9.7.4 was used to perform all of the building modeling
and analysis. Modeling was done in three-dimensions and analysis cases
were linear elastic. Microsoft excel was also used to plot graph from data
analysis.
3.4 Loads
Before a structure can be analysed, the nature & magnitude of loads must be
known.
Following are the important type of loads:
Dead Load: This can be precisely known. Weight of the structure &
components permanently attached to the structure contribute to the dead
load.
Live Load: From BNBC we get the live load values for different types of
buildings.
Wind force: These loads are often of such short of cyclic variation so as to
cause inertial forces in the structure. In addition to the applied loads there
are effects that cause dimensional changes in the structure. If these changes
are prevented by the support conditions of a structure, internal stresses that
must to be calculated.
3.4.1 Dead Load & Live Load Calculation
We have considered dead load as per follows.
Floor to floor height = 10 ft

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Brick wall width = 5 inch
Concrete unit weight = 150 pcf
Brick unit weight = 120 pcf
Super Dead Load = 80 psf
Live Loads: Live loads are as per BNBC 2015
On floor = 60 psf
On roof = 30 psf
3.4.2 Wind Load Calculation: We know that
Wind Pressure, Pz = 0.00256*Ci*Cz*CG*Ct*Cp*Vb
2 ………………(3.1)
Wind Force, Fz = B*heff*Pz …………………………………………(3.2)
Here,
Vb = Wind velocity (mph) = 130 mph
Ci = Importance Factor = 1.25
Ct = Local topography factor = 1
Cp = Wind pressure co-efficient
B = Width of building
Z= Elevation
CG = Gust factor
Cz = Zone co-efficient
Cp = ( X direction 1.546) and ( Y direction 1.263)

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Wind loads is givenbelow:
Table 3.1: Wind load along X axis and along Y axis.
Wind Load
Storey No (kip)
Along X axis Along Y axis
1 60.94 29.18
2 68.86 32.98
3 78.88 37.78
4 88.58 42.42
5 92.14 44.12
6 97.95 46.91
7 100.86 48.3
8 106.68 51.09
9 109.59 52.48
10 104.42 50.01

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52.48
Distribution of wind load in each storey is given below:
Figure 3.1: Wind load (kip) in Y axis each storeys

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Figure 3.2: Wind load (kip) in X axis each storeys.
104.42
109.59
106.68
100.68
97.95
92.14
85.58
78.88
68.86
60.94

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3.4.3 Load Combinations: Load combinations are as per BNBC
1. 1.4DL
2. 1.4DL+1.7LL
3. 1.4DL+1.4SD
4. 0.9DL+1.3WL
5. .9DL+1.7H
6. 1.4DL+1.7LL+1.7H
7. 0.75(1.4DL+1.4SD+1.7LL)
8. 0.75(1.4DL+1.4SD+1.7WL)
9. 0.75(1.4DL+1.4LL+1.7WL)
10.0.75(1.4DL+1.4LL+1.7H)
LL = Live Load, WL = Wind Load, DL= Dead Load, SD= Super Dead Load
For the drift calculations the loads applied to the structure were unfactored. All
of the building models were subjected to the same unfactored wind loads
calculated in Section 3.4.2 and gravity loads based on the information given in
section 3.4.1. The full live load was reduced according to BNBC 2015.
1.0 DL + 1.0 LL + 1.0 WL - - - - - - - - - - - - (3.1)
Combination 3.1 shows the loading combination used for drift calculations.
3.5 Analysis of Models
Each of the individual sections in Section 3.5 focuses on the following unique
modeling parameters and how the model is affected by the modeling
assumptions:
For 10 storied building:

1. Varying moment of inertia of column by keeping area constant
without shear wall.
2. Varying moment of inertia of column by keeping area constant with
shear wall.

27
3. Varying moment of inertia of beam without shear wall.
4. Varying moment of inertia of beam with shear wall.
3.5.1 Varying Moment of Inertia of Column by Keeping Area Constant
without Shear Wall.
First we analyses for column size 18”x18”= I, then 15”x22” = 1.5I & finally
12”x27” = 2I
Figure 3.3: Column layout plan for size 18”x18” without shear wall
Figure 3.4: Column layout plan for size 15”x22” without shear wall

28
Figure 3.5: Column layout plan for size 12”x27” without shear wall.
Analysis of the structures with and without shear wall were performed in
software. First two modes are shown below in table.
Figure 3.6: Frame only structure (without shear wall) undeformed shape in
X direction.

29
Figure 3.7: Frame only structure (without shear wall) undeformed shape in
Y direction.
Figure 3.8: Frame only structure (without shear wall) deformed shape in X
direction.

30
Figure 3.9: Frame only structure (without shear wall) deformed shape in Y
direction.
Values of Storey Drift from ETABS Analysis for Varying Moment of
Inertia of Column by Keeping Area Constant Without Shear Wall.
Table 3.2: Values of Storey Drift from ETABS Analysis for Varying
Moment of Inertia of Column by Keeping Area Constant Without Shear
Wall.
Storey Storey Drift for Storey Drift for Storey Drift for
No Colum n 18”X18” Colum n 15”X22” Column 12”X27”
(in) (in) (in)
10 2.063680 1.934297 1.828990
9 2.017466 1.885431 1.775832
8 1.935825 1.804882 1.694307
7 1.813128 1.686343 1.577664
6 1.649461 1.529137 1.424584
5 1.446155 1.334380 1.236034
4 1.205651 1.104648 1.014916
3 0.931231 0.844129 0.766515
2 0.630216 0.561935 0.501720
1 0.320962 0.279240 0.243556

31
3.5.2 Shear Force and Bending Moment Diagrams for Columns
Figure 3.10: Shear force and Bending Moment diagrams for column size
18”x18”.

32
Figure 3.11: Shear force and Bending Moment diagrams for column size
15”x22”.

33
Figure 3.12: Shear force and bending moment diagrams for column size
12”x27”.

34
3.5.3 The Unfactored (DL+LL) Reactions in Various Columns
Table 3.3: The Unfactored (DL+LL) Reactions in Various Columns
Node Column 18”x18” Column 15”x22” Column 12”x27”
No. (kip) (kip) (kip)
1 264.8 202.60 201.47
2 448.94 393.02 388.93
3 415.98 358.90 355.13
4 203.6 166.58 165.68
5 451.5 401.37 404.93
6 783.69 781.48 784.03
7 724.34 713.54 716.23
8 392.89 334.94 339.20
9 421.21 368.57 369.39
10 729.77 716.61 714.27
11 649.75 625.13 623.07
12 288.23 231.36 233.95
13 421.92 369.42 370.27
14 729.53 715.88 712.99
15 493.86 463.07 458.51
16 451.41 401.82 405.43
17 783.57 781.29 783.74
18 720.26 709.25 711.51
19 386.40 328.09 330.97
20 265.26 204.08 203.28
21 449.76 394.01 390.14
22 417.35 360.60 357.22
23 230.56 167.15 166.44
From the above table it is found that the base reaction of columns is almost
same for changing the moment of inertia of columns keeping area constant. So

35
if we change moment of inertia of column for reducing storey drift, foundation
cost will not increase.
3.5.4 Varying Moment of Inertia of Column by Keeping Area Constant
with Shear Wall
First we analyses for column size 18”x18”= I, then 15”x22” = 1.5I & finally
12”x27” = 2I with shear wall in lift core.
Figure 3.13: Column layout plan for size 18”x18” with shear wall.

36
After analysis Frame with shear wall:
Figure 3.16: Undeformed shape of frame (with shear wall). X direction

37
Figure 3.17: Undeformed shape of frame (with shear wall). Y direction
Figure 3.18: Deformed shape of frame (with shear wall). X direction

38
Figure 3.19: Deformed shape of frame (with shear wall). Y direction

39
Values of Storey Drift from ETABS Analysis for Varying Moment of
Inertia of Column by Keeping Area Constant (With Shear Wall)
Table 3.4: Values of Storey Drift from ETABS Analysis for Varying Moment
of Inertia of Column by Keeping Area Constant (With Shear Wall).
No Colum n 18”X18” Colum n 15”X22” Colum n 12”X27”
(in) (in) (in)
10 1.249830 1.180958 1.080565
9 1.147117 1.084847 0.975356
8 1.034555 0.979150 0.860315
7 0.911980 0.863640 0.735717
6 0.779660 0.738545 0.603471
5 0.639608 0.605781 0.467087
4 0.495516 0.468873 0.331638
3 0.352653 0.332927 0.204275
2 0.218379 0.205130 0.094651
1 0.102490 0.095171 0.016791

40
3.5.5 Varying moment of inertiaof beam without shear wall
We analyses for beam size 12”x21”=I, 12”x24”=1.5I, 12”x27”=2I
Figure 3.20: Beam layout plan for size 12”x21” without shear wall.

41
Values of Storey Drift from ETABS Analysis for varying moment of
inertiaof beam without shear wall
Table 3.5: Values of Storey Drift from ETABS Analysis for varying moment
of inertia of beam without shear wall
No Beam 12”X21” Beam 12”x24” Beam 12”X27”
(in) (in) (in)
10 2.576689 2.330019 2.133819
9 2.493304 2.256773 2.068338
8 2.371324 2.148103 1.969906
7 2.200977 1.995497 1.831112
6 1.980257 1.797428 1.650811
5 1.710642 1.555279 1.430305
4 1.396499 1.272780 1.172870
3 1.045915 0.956645 0.884192
2 0.675318 0.295376 0.275686
1 0.319377 0.052771 0.049583

42
3.5.6 Varying moment of inertiaof beam withshear wall
We analyses for beam size 12”x21”=I, 12”x24”=1.5I & 12”x27”=2I
Figure 3.23: Beam layout plan for size 12”x21” with shear wall.

43
Values of Storey Drift from ETABS Analysis for varying moment of
inertiaof beam withshear wall
Table 3.6 Values of Storey Drift from ETABS Analysis for varying moment of
inertia of beam with shear wall
No Beam 12”X21” Beam 12”x24” Beam 12”X27”
(in) (in) (in)
10 0.910768 0.854072 0.806581
9 0.816781 0.768789 0.728431
8 0.711453 0.672160 0.639004
7 0.602932 0.571939 0.545679
6 0.492309 0.469043 0.449238
5 0.381093 0.364825 0.350904
4 0.273072 0.262839 0.254033
3 0.173722 0.168298 0.163601
2 0.090663 0.088571 0.086748
1 0.032886 0.032538 0.032232

44
CHAPTER IV
RESULTS AND DISCUSSION
4.1 Introduction
In this chapter, a parametric study is done on a particular frame with or without
shear wall by changing parameters. There are a lots of parameters affecting the
result. The parameters that will be discussed in this chapter are
 Variation of column shape without shear wall
 Variation of column shape with shear wall
 Variation of beam size without shear wall
 Variation of beam size with shear wall
Shear wall incorporation in the structure makes its more effective in resisting
the lateral load. If thickness of the shear wall is reduced the structure may
behave differently. So a model was developed with shear wall of thickness 6
inches.
The graphical representation of these data variation is given from next page.
4.2 Variation of Column Shape without Shear Wall
The graph of No. of storey vs storey drift for various column shape is given
below:
Figure 4.1: Effect of column Shape on Storey Drift (without shear wall)
0
0.5
1
1.5
2
2.5
0 5 10 15
StoreyDriftinYDirection
(inch)
Number of Storey
Effect Of Column Shape On Storey Drift (Without Shear
Wall)
18”X18”
15”X22”
12”X27”
Beam12”x21”.

45
From the above graph
 For Column size 18”x18” (I) top drift is 2.06368”, for column size
15”x22” (1.5I) top drift is 1.934297” & for column size 12”x27” (2I)
top drift is 1.82899”.
 We see that if we increase moment of inertia of column about X axis
then the storey drift in Y axis will decrease.
 For 10 storied building without shear wall storey drift don’t exceed
BNBC limits.
Figure 4.2:% Decrease of storey drift vs % Increase of moment of inertia of
column
 For 50% increase of moment of inertia of column, top drift decreases
5.5%.

 For 100% increase of moment of inertia of column, top drift decreases
8.5%.
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100 120
%Decreaseofstoreydrift
Increase of moment of inertia of column %

46
4.3 Variation of Column Shape withShear Wall
The graph of No. of storey vs storey drift for various column shape (with shear
wall) is given below:
Figure 4.3: Effect of column Shape on Storey Drift (with shear wall)
 For Column size 18”x18” (I) top drift is 1.24983”, for column size
15”x22” (1.5I) top drift is 1.180958” & for column size 12”x27” (2I)
top drift is 1.080565”.

 When we provide shear wall top drift decreases significantly.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 2 4 6 8 10 12
StoreyDriftinYDirection(inch)
Number of Storey
Effect of column Shape on Storey Drift (with shear Wall)
18”X18”
15”X22”
12”X27”
Beam12”x21”.

47
4.4 Variation of Beam Size without Shear Wall
The graph of No. of storey vs storey drift for various beam shape (without
shear wall) is given below:
Figure 4.4: Effect of Beam Size on Storey Drift (without shear wall)
 For beam size 12”x21” top drift is 2.576689”, for beam size 12”x24”
top drift is 2.330019” & for beam size 12”x27” top drift is 2.133819”

 We see that if we increase moment of inertia of beam then the storey
drift will decrease.
0
0.5
1
1.5
2
2.5
3
0 2 4 6 8 10 12
StoreyDriftinYDirection(in)
Number of Storey
Effect of Beam Size on Storey Drift (without shear wall)
12”X21”
12”x24”
12”X27”
column 15”x22”

48
Figure 4.5: % Decrease of storey drift vs % Increase of moment of inertia of
beam
 For 50% increase of moment of inertia of beam, top drift decreases
9.57%.

 For 100% increase of moment of inertia of column, top drift
decreases 11.19%.
4.5 Variation of Beam Size withShear Wall
The graph of No. of storey vs storey drift for various beam size (with shear
wall) is given below:
Figure 4.6: Effect of Beam Size on Storey Drift (with shear wall)
0
2
4
6
8
10
12
14
16
18
20
0 20 40 60 80 100 120
%Decreaseofstoreydrift
Increase of moment of inertia of beam %
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12
StoreyDriftinYDirection(in)
Number of Storey
Effect of Beam Size on Storey Drift (with shear wall)
12”X21”
12”x24”
12”X27”
column 15”x22”

49
 For beam size 12”x21” top drift is 0.910768”, for beam size
12”x24” top drift is 0.854072”& for beam size 12”x27” top drift is
0.806581”
 When we provide shear wall top drift decreases significantly.

50
CHAPTER V
CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusion
With respect to serviceability, designing for drift is done to prevent or limit
unacceptable damage to non-structural building components such as interior
cladding and partitions as well as to ensure the functionality of mechanical
systems such as elevators. Adequate building stiffness is obtained by designing
a building to be within reasonable drift limits.
This thesis investigated these sources of discrepancy through a thorough
review of the literature (Chapter 2), an analytical study of a typical 10 storey
commercial building (Chapter 3), an analytical study on the sources of member
deformations (Chapter 4) and by developing a survey to assess the current state
of the professional practice.
In other words, this thesis was undertaken and written with the intention of
suggesting and establishing a comprehensive, performance based approach to
the wind drift design of RCC building.
5.2 Major Findings
The findings of the thesis may be concluded as such
 By increasing moment of inertia of column double provides more
“percent decrease of top drift” than by increasing moment of inertia
1.5 times.
 If the columns behave more like a shear wall in weak direction, it
will give less storey drift.
 By increasing moment of inertia of beam double provides more
“percent decrease of top drift” than by increasing moment of inertia
1.5 times.

51
 Increasing moment of inertia of column is more efficient than
increasing moment of inertia of beam.

 Providing shear wall in lift core is not necessary in ten storied RCC
building to maintain BNBC drift limits.
 Since construction cost of structure depends on the area of concrete
so it is better to increase the moment of inertia of the elements of the
structure rather than area.
 Reinforcement requirement decreases with the increase of moment
of inertia of columns.
 It is found that the base reaction of columns is almost same for
changing the moment of inertia of columns keeping area constant.
So if we change moment of inertia of column for reducing storey
drift, foundation cost will not increase.
5.3 Recommendation for Reducing Drift
 It is the moment of inertia of column not the area that should be
increased to reduce storey drift efficiently.

 Columns should be placed in the plan such a way that it behaves like
a shear wall in weak direction. Because if the columns behave more
like a shear wall in weak direction, it will give less storey drift.

 Shear wall is not necessary up to ten storied buildings but it may be
necessary in higher than ten storied buildings.

 To control the lateral drift effectively, the structural system,
consisted of reinforced concrete shear wall, moment resisting system
can be used.

 The position of core in plan close to the center is important, to
promote the efficiency of structural system.

52
REFERENCES
BNBC (2015), Bangladesh National Building Code, House and Building
Research Institute, Mirpur, Dhaka.
Smith, S. B. , Coull, A. “Tall Building Structures: Analysis and Design”.
Armitt, J. (1980). “Wind Loading on Cooling Towers”. Journal of the
Structural Division. Vol. 106, no. 3, pp. 623-641. Mar. 1980.
Charney, F.A. (1990). “Wind drift serviceability limit state design of
multistorey buildings.” Journal of Wind Engineering and Industrial
Aerodynamics. Vol. 36.
Mills,I.(2007).“The Eiffel Tower, Paris”.
http://www.discoverfrance.net/France/Paris/Monuments-Paris/Eiffel.shtml
“Drift and damage considerations in earthquake resistant design of reinforced
concrete buildings.” Ph.D. Dissertation, Department of Civil Engineering,
University of Illinois at Urbana.
LeMessurier, W. (1993). “Breaking barriers.” Modern Steel Construction. Vol.
33 No. 9. pp. 26-33
Sutro, Dirk. (2000). “Into the Tunnel.” Civil Engineering Magazine. June 2000.
ASCE (1988). Task Committee on Drift Control of Steel Buildings of
the
Committee on the Design of Steel Buildings. “Wind Drift Design of Steel-
Framed Buildings: A State of the Art Report.” Journal of Structural
Engineering ASCE, Volume 114.
Naeim F. (2001) “Design for Drift and Lateral Stability” john A. Martin
Associates, Inc. pp 327-372

53
Rahman A. (2012), “Analysis of drift due to wind loads and earthquake Loads
on tall structures by programming language c”International
Journal of Scientific & Engineering Research, Volume 3, Issue 6.
Khouri M. F (2011) “Drift Limitations in a Shear Wall Considering a Cracked
Section” International Journal of Reliability and Safety of Engineering
Systems and Structures (IJRSESS)
Nilson A. H, (2010). “Design of concrete structures” Fourteenth Edition The
McGraw Hill Companies,
Smith, B.S. and Coull, A. (1991) “Tall building structures: analysis and
design”: John wiley & sons, Inc. Singapore.
Hassoun M (2008)” Structural Concrete” John wiley & sons, Inc. Fourth
Edition.
http://www.uphcp.org/index.php/ngo/ngo_details_information/ SCC%20PA-1 [
Accessed 20 November 2013]
Williams A. (2005),”Civil and Structural Engineering” Kaplan AEC Education
Inc, Fifth Edition. .

54
APPENDIX A
Table A 1: Adjustment factor for building height and Exposure.

55
Table A 2: Importance factor, I for different occupancy categories
(Adopted from BNBC, 2015)
Occupancy category Importance factor, I
I or II 1.0
III 1.25
IV 1.5
Table A 3: Pressure coefficient, Cp

56
Figure A 1: Basic wind speed map in Bangladesh.

EFFECT OF COLUMN, BEAM SHAPE AND SHEAR WALL ON STOREY DRIFT

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