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Comparative study of tall structures with softstorey openings and shearwall
1. COMPARATIVE STUDY OF TALL
STRUCTURES WITH
SOFTSTOREY OPENINGS
AND SHEARWALLS
Submitted by
Name: SHREEHARI KULKARNI
USN.: SG21SEC017
Under the Guidance of
Asst. Prof. RISHIKESH
2. SHARNBASVA UNIVERSITY KALBURGI
PROJECT III
ON
COMPARATIVE STUDY OF TALL STRUCTURES WITH
SOFTSTOREY OPENINGS
AND SHEARWALLS
Submitted by
Name: SHREEHARI KULKARNI
USN.: SG21SEC017
Under the Guidance of
Asst. Prof. RISHIKESH
Asst.Prof . Vishwanath (EQRS)
Asst.Prof. Sourabh (Tall structure)
Faculty of Engineering and Technology
Structural Engineering
Sharnbasva University
Kalaburagi-585103
3. CONTENTS
• INTRODUCTION
• LITERATURE REVIEW
• AIM AND OJECTIVE
• METHODOLOGY
• SOFT STOREY
• SHEAR WALL
• ETABS
• METHODS FOR ANALYSIS
• PROCEDURE
• METHODOLOGY AND MODELLING
• ANALYSIS OF MULTISTOREY BUILDING USING ETABS
• PREVIOUS YEAR PAPER CONCLUSIONS
• DISCUSSIONS
• REFERENCES
4. INTRODUCTION
The increase in urbanization for the past few years has made the vehicle
parking a major concern. In order to overcome this usually we provide the
first storey of the building for parking. The open ground storied structure
is a structure in which the infill wall is absent at the ground storey for the
purpose of parking or social gathering. According to earthquake reports
the structure having open ground storey leads to complete collapse due to
absence of infill wall. Distribution of strength, mass, stiffness should be
consistent throughout the building both vertically and horizontally as per
design philosophy of structures. Improper orientation of walls results in
soft storey, weak storey and torsion effect. The severe damage can be
seen on the structure due to irregularity of structures. Due to modern era
of construction the buildings without open ground storey is unavoidable
because there is shortage of area for parking so we have to provide some
special measures on the structure to mitigate the effect of soft storey on
the structure . It is very necessary to conduct an in-depth study on the
nonlinear behavior of the structure so that it gives the proper response of
the structure during earthquakes.
5. Shear wall structural systems
For a shear wall structural system, the core shear walls are generally
provided around the perimeter of the core area to encompass lift shafts
and lobbies, staircases and primary vertical services shafts. For maximum
Structural efficiency, core walls should be as long as possible and, ideally,
symmetrically placed relative to centre lines of the building.
The properties of a building are lateral stiffness, lateral strength and
ductility. Lateral stiffness refers to the initial stiffness of the building, even
though stiffness of the building reduces with increasing damage. Lateral
strength refers to the maximum resistance that the building offers during
its entire history of resistance to relative deformation. Ductility towards
lateral deformation refers the ratio of the maximum deformation and the
idealized yield deformation. The effect of the vertical component of
ground motion is generally considered not to be significant and is
neglected except in cantilevers.
6. AIM AND OBJECTIVE
Modeling the building using the software ETABS
Applying gravity loads and different load combinations as per Indian codal provision.
To perform analysis and design of multi storey buildings for soft storey effect using
response spectrum analysis method.
To compare the behavior of multi storey buildings having soft storey designed with
and without shear wall
To carryout lateral load analysis for building models as per codes.
To compare the structural response of multistorey building having soft storey with
different type of shear wall arrangements on building structure and finding of best
soft storey seismic forces resistant building from the models.
To find the constraints such as time period, storey displacement, storey driftt, storey
stiffness and base shear.
To study the seismic behavior of RC framed building with soft storey effect at
different floor levels.
To analyze structural parameters influenced by the effect of soft storey.
To analyze the structural parameters after the application of retrofitting measures in
soft storey building.
7. LITERATURE REVIEW
Devendra Dohare and Dr. Savita Maru, “Seismic Behavior of Soft Storey
Building:A Critical Review”-
In this paper an investigation has been made to study the seismic behavior
of soft storey building with different arrangement in soft storey building
when subjected to static and dynamic earthquake loading. It is observed
that , providing infill improves resistant behavior of the structure when
compared to soft storey provided. It has been found earthquake forces by
treating them as ordinary frames results in an underestimation of base
shear. Investigators analysis numerically and use various computer
programs such as Staad Pro, ETABS, SAP2000 etc. Calculation shows that,
when RC framed buildings having brick masonry infill on upper floor with
soft ground floors subjected to earthquake loading, base shear can be
more than twice to that predicted by equivalent earthquake force method
with or without infill or even by response spectrum method when no infill
in the analysis model.
8. Hiral .D. Adhiya and Dr. P. S. Pajgade “Review on Effective utilization of
RCC Shear walls for Design of Soft Storey Buildings”-This study
investigates the analytical results and designing provisions for soft storey
buildings with and without shear walls. They concluded that it is very
necessary to locate the effective position of shear wall otherwise it will
create overturning and twisting effect on the structure. They has studied
the behavior of multi storey building for soft storey effect, shear wall and
struts using equivalent static analysis method using ETAAB2015. In the
thesis, the multi storey buildings of G+9 Storey are modeled in five
different configurations and are compared in EQX and EQY respectively
considering parameters such as storey drift, displacement, column
bending moment, column shear force, column area of steel, beam bending
moment, beam shear force, beam area of steel, shear wall bending
moment, shear wall shear force, shear wall area of steel. They have
concluded that storey displacement and storey drift parameters are
considerably reduced with the help of shear wall effect and struts.
9. Vipin V.Halde and Aditi H. Deshmukh, “Review
on Behavior Of Soft Storey In Building”-In this
study the focus is on the investigation of the
effect of the soft storey on the behavior of the
structure. This is a therotical study of behavior of
soft storey under earthquake,causes of failures in
soft storey and effect of irregularirties on soft
storey. They concluded that deflection of floor
has increased when soft storey is considered.
Hence it is suggested that expert designs and
detailing are needed in soft storey building.
10. Dr. Saraswati Setia and Vineet Sharma, ‘Seismic Response
of R.C.C Building with Soft Storey’- They investigated the
influence of some parameters on behavior of a building
with soft storey. The modeling of the whole building is
carried out using the computer program STAAD.Pro 2006.
Parametric studies on displacement, inter storey drift and
storey shear have been carried out using equivalent static
analysis to investigate the influence of these parameter on
the behavior of buildings with soft storey. The selected
building analyzed through five numerical models.
Concluded minimum displacement for corner column is
observed in the building in which a shear wall is introduced
in X-direction as well as in Z-direction.
11. • Venkata Sairam Kumar.N et.al.4 reviewed various papers on shear walls
and stated that shear walls are structural systems which provide stability
to structures from lateral loads like wind, seismic loads. These structural
systems are constructed by reinforced concrete, plywood/timber
unreinforced masonry, reinforced masonry at which these systems are
sub divided into coupled shear walls, shear wall frames, shear panels
and staggered walls. The paper was made in the interest of studying
various research works involved in enhancement of shear walls and their
behaviour towards lateral loads. As shear walls resists major portions of
lateral loads in the lower portion of the buildings and the frame supports
the lateral loads in the upper portions of building which is suited for soft
storey high rise building. Building which are similar in nature constructed
in India, as in India base floors are used for parking and garages or
officers and upper floors are used for residential purposes. They have
concluded with a broad note that researches was carried mainly on
application of cyclic load tests and behaviour of different types of shear
walls in cyclic application of loads. Researchers studied various
parameters like enhancement of stiffness, drift, development forces in
buildings and also to observe perfect location of shear wall location in
building frame for construction. It was seen that any type of building
which is tall and can be affected with lateral forces like earthquake and
wind forces can be constructed with shear walls. Shear walls can be used
as lateral load resisting systems and also retrofitting of structures.
Internal shear walls are more efficient than external shear walls when
compared with cyclic load tests by researchers.
12. P. P. Chandurkar et.al.2 investigated about a building with Shear wall and
without Shear wall were considered and compared. As per their research
work Structural walls provide an efficient bracing system and offer great
potential for lateral load resistance. The properties of these seismic shear
walls dominate the response of the buildings, and therefore, it is
important to evaluate the seismic response of the walls appropriately.
According to their study, main focus was to determine the solution for
shear wall location in multi-storey building. Effectiveness of shear wall had
been studied with the help of four different models. One model was bare
frame structural system and other three models were dual type structural
system. When earthquake load were applied to the building of ten stories
located in zone II, zone III, zone IV and zone V, parameters like Lateral
displacement, story drift and total cost required for ground floor were
calculated in both the cases replacing column with shear wall. E- Tabs
software was adopted for analysis. From the analysis, it is observed that in
10 story building, constructing building with shear wall in short span at
corner model 4) is economical as compared with other models. Thus large
dimension of shear wall is not effective in 10 stories or below 10 stories
buildings. It was observed that the shear wall is economical and effective
in high rise building. From the research work it was observed that
changing the position of shear wall will affect the attraction of forces, so
that wall must be in proper position. Also if the dimensions of shear wall
are large then major amount of horizontal forces are taken by shear wall.
Providing shear walls at adequate locations substantially reduces the
displacements due to earthquake.
13. Prof. Patil S.S. and Mr. Sagare S. D.,’ Dynamic Analysis of
Soft Storey-High Rise Building with Shear Wall’- They
studied a building with open ground storey to bring out the
importance of explicitly recognizing the presence of soft
ground storey in the analysis. Usually the most economical
way to eliminate the failure of soft storey by adding shear
walls. The shear walls are one of the most efficient lateral
force resisting elements in high rise buildings. This paper
deals with occurring of soft storey at lower level at high rise
building subjected to earthquake has been studied. Also
has been tried to investigate on adding of shear wall to
structures in order to reduce soft storey effect on seismic
response of building.
14. P.B.Lamb, Dr R.S. Londhe, ‘Seismic Behavior of Soft
First Storey’– They studied a building with the help of
different mathematical models considering various
methods for improving the seismic performance of the
building with soft first storey. Analytical models
represent all existing components that influence the
mass, strength, stiffness and deformability of structure.
The equivalent static and multimodal dynamic analysis
is carried out on the entire mathematical 3D model
using the software SAP2000 and the comparisons of
these models are presented. Finally, the performance
of all the building models is observed in high seismic
zone V.
15. Khan and Vyawahare (2013) carried out the non-
linear response of RC frame high rise building
with soft storey at different levels in addition to
one at ground floor. Their objective was to see
the variation of load- displacement graph and
check the maximum base shear and displacement
of the frame with soft stories at different levels.
After obtaining pushover curve the concluded
that as the soft storey is shifted to higher level
intensity of hinge formation becomes lower and
lower and at the same time displacement
increases and base shear also increases.
16. Hejazi (2011) discussed the effect of soft
storey on structural response of high rise
buildings. The paper highlights the occurring
of soft storey at the lower level of high rise
buildings subjected to earthquake has been
studied. Also has been tried to investigate on
adding of bracing in various arrangements to
structure in order to reduce soft story effect
on seismic response of building.
17. Dr. Saraswati Setia (2012) discussed dynamic ductility
demand during probable earthquake. The stilt floor
used in severely damaged or collapsed RC buildings
introduced irregularity of sudden change of stiffness
between ground storey and upper stories. In the upper
stories brick infill walls were used due to which it
increases the lateral stiffness of the frame by a factor
of 3 to 4 times. For such buildings the dynamic ductility
demand during probable earthquake gets only
concentrated in the soft storey and the upper stories
tends to elastic. In such buildings, the stiffness of the
lateral load resisting systems at those stories was quite
less than the stories above or below. Parametric
studies on displacement, inter storey drift and storey
shear have been carried out using equivalent static
analysis to investigate the influence of these parameter
on the behavior of buildings with soft storey.
18. Furtade and Anibal investigated the global
structural safety of an existing building with a
potential soft-storey mechanism and observed
that a correct assessment of the building safety
can be achieved by considering the presence of
infill masonry walls. The absence of the infills on
the ground floor introduced a soft-storey
mechanism on the structure when submitted to
seismic actions. Four different strengthening
techniques were proposed and it is observed that
the most efficient way for reducing the maximum
drift was the addition of steel braces. This
technique was the only one which succeeded in
removing the soft-storey mechanism.
19. Umesh P. Patil et al analysed the seismic
performance of two structures G+15, one made of
composite steel concrete material and other one is made
up of RCC, situated in the earth quake zone III, having a
medium soil were investigated analytically for their
performance using ETABS software, Equivalent static
method is used for the analysis of RCC. It is possible to
control the drift in soft storey by providing 1) Shear walls
2) Bracings 3) Stiffer column 4) Lateral load resisting
system. The beams and columns in the soft storey are
designed 2.5 times of obtained bending moments and
shear forces and shear walls are designed by a factor of
1.5 times the storey shear.
20. Mohammed KhajaMoiuddin et al conducted a
study on 12 different models of 21 storey building model,
the model was analyzed for time period using both
ETABS and SAP2000, the base shear was calculated
using both response spectrum analysis, and equivalent
static analysis. When the structural action of masonry
infill is taken the fundamental natural time got reduced
58% when compare with bare frame model.
21. SuchitaHirde (2014) analysed Four models with soft storey
at different levels are considered along with soft storey at
ground level and these models with incorporation of shear
walls are considered. Pushover analyses of the models
with and without shear walls are carried out. This study
highlights the poor seismic performance of G+20 RCC
building with soft storey. After retrofitting of all the
models with shear walls hinges are not developed in any
of the columns. Provision of shear walls results in
reduction in lateral displacement. Displacement reduces
when the soft storey is provided at higher level. After
retrofitting the base shear carrying capacity is increased by
8.45% to 13.26%.
22. Spoorthi et al(2014)performed a pushover analysis of a
tall building with symmetrical plan and elevation of
5,10,15 storey building, and they buildings were analyzed
by using ETABS 9.7.4 for seismic zone V. Base shear,
storey displacements, storey drifts and storey shears
obtained from pushover analysis are about twice the storey
displacements, storey drifts and storey shears of equivalent
static analysis
SuchitaHirde (2014) analysed Four models with soft storey
at different levels are considered along with soft storey at
ground level and these models with incorporation of shear
walls are considered. Pushover analyses of the models
with and without shear walls are carried out. This study
highlights the poor seismic performance of G+20 RCC
building with soft storey. After retrofitting of all the
models with shear walls hinges are not developed in any
of the columns. Provision of shear walls results in
reduction in lateral displacement. Displacement reduces
when the soft storey is provided at higher level. After
retrofitting the base shear carrying capacity is increased by
8.45% to 13.26%.
23. Susanta Banerjee et al (2014) analysed three types of
buildings in which the building designates. All buildings
are analyzed as Ordinary Moment Resisting frames.
Designs are carried out in STAAD-Pro. The drift demands
for ground storey column are large for soft storey
buildings. Soft storey building shows poor performance
during earthquake.
Munde et al (2012) has analyzed four types of frame
models such as bare frame, Frame with infill except the
first storey, First storey containing wall at specific
locations, Soft first storey with stiffer column compared
with other storey columns. The linear elastic analysis was
made using ETABS on these frames The drift and the
strength demands in the first storey columns are very large
for buildings with soft ground storeys, increasing the
stiffness’s of the first storey such that the first storey
stiffness is at least 50% as stiff as the second storey.
24. Haroon Rasheed Tamboli et al (2012) has performed a
study which involves seismic analysis of RC frame (ten
storey) building with different models that include bare
frame, infilled frame and open first storey frame. The
parameters such as base shear, time period, natural
frequency, storey drift and bending moments are studied,
the building model was analysed using ETABS. In case of
an open first storey frame structure, the storey drift is very
large than the upper storeys, which may cause the collapse
of structure during strong earthquake shaking.
Saraswati Setia et al (2012) has performed a study on 6
storied RC frame building model and is analysed using the
software STAAD PRO.2006. The static analysis is then
performed for the modeled RC frame building using the
computer software STAAD PRO. 2006. Lateral
displacement is largest in bare frame with soft storey
defect both for earthquake force for corner columns as
well as for intermediate columns. Buildings with shear
wall in core and shear wall have uniform displacement
because of shear wall. Which shows a gradual change of
stiffness between the lower soft storey and the upper floors
that is essentially required.
25. DEFINITIONS
Storey: when the multi-story building or the
residential building is constructed in that
when the floor to floor gap will be there that
is the story.
Storey Shear (VI): We will calculated all the
lateral loads at each floor of the building.
26. Soft Storey
Now a day construction of multi-storeyed high rise Reinforced Concrete (RC) frame
buildings is becoming common in country like India. The most common type of
vertical irregularity occurs in buildings that have an open ground story. Many
buildings constructed in recent times have a special feature that some stories
within the building are left open for the purpose of parking, reception, offices,
service purpose etc. Such buildings are often called open storey or soft storey
buildings or buildings on stilts. Such stories become soft and weak relative to the
other stories, due absence of masonry walls in the storey. Structurally those
unbalances are not safe and unhealthy and soft storey buildings are well known
for being susceptible to collapse through past earthquakes.
28. A soft story known as weak story is defined as
a story in a building that has substantially less
resistance or stiffness or inadequate ductility
(energy absorption capacity) to resist the
earthquake induced building stresses. Soft
story buildings are characterized by having a
story which has a lot of open space Parking
garages, for example, are often soft stories, as
are large retail spaces or floors with a lot of
windows
29. • The presence of walls in upper storeys makes the building many times stiffer in the
upper storeys than in the open ground storey .Thus, the upper storeys move
almost together as a single block, and most of the horizontal displacement of the
building occurs in the open ground storey and columns in the open ground storey
are severely stressed. If the columns are weak they do not have the required
strength to resist these high stresses, they may be severely damaged or even lead
to collapse of the building . After the collapses of R.C frame buildings in Bhuj
Earthquake the IS Code 1893(Part-I) 2002 “Criteria for earthquake resistant design
of structures” had involved the special design provisions related to soft storey
buildings. As per IS 1893-2002 (Part-I) Soft Storey is defined as storey in which
lateral strength is less than 80% of that in the storey above. But the stiffness
irregularity remains in the building as per this code. So new code (IS 1893 -
2016(Part-I)) recommends that storey in which lateral strength of all structural
members less than that in the storey above is treated as soft storey.
• Reinforced-concrete framed structure in recent times has a special feature i.e the
ground story is left open for the purpose of social and functional needs like vehicle
parking, shops, reception lobbies, a large space for meeting rooms or a banking
hall etc. such buildings are often called open ground storey buildings or soft storey
buildings. Experience of different nations with the poor and devastating
performance of such buildings during earthquakes always seriously discouraged
construction of such a building with a soft ground floor. This storey known as weak
storey because this storey stiffness is lower compare to above storey. So that easily
collapses by earthquake.
34. Distribution of total displacement
generated by an earthquake
a) Regular building b) Building with soft story
35.
36. Shear Walls
Shear walls are plane elements made up of reinforced concrete thin
walls having length and thickness providing lateral stiffness. The
shear and overall flexural deformations are design constraints,
along with the stress levels, axial and bending. Concrete shear walls
may be cast in place or pre-cast. Pre-cast panel walls are also used
within a concrete or steel frame to provide lateral resistance. The
ductile shear walls used in earthquake resistant design have to be
detailed carefully. Coupling beams should have diagonal
reinforcement to develop shear resistance. Steel shear walls are
also used sometimes, by connecting them to framework by welding
or high strength bolts. Masonry shear walls are also used, with solid
walls and grouted cavity masonry to carry shears and moments,
with reinforcements encased.
38. Advantages of Shear Walls in RC
Buildings:
• Shear wall resist horizontal lateral force and provide earthquake resistance
• It possess very large in-plane stiffness which resist lateral load
• Shear walls are helpful in controlling deflection.
• RCC shear walls are easy to construct – reinforcement detailing
• It minimizes earthquake damage to structural damage and non-structural damages.
• Well-designed shear walls not only provide adequate safety but also provide great
measure of protection against costly non- structural damage during moderate seismic
damages.
• It provides adequate strength to resist large lateral loads without excessive additional cost.
• It provides adequate stiffness to resist lateral displacement within permissible limits, thus
reducing risk of non-structural damage.
• They should be located such a way that they also act as functional walls and do not interfere
with the architectural of the building.
• Shear wall should be placed along both the axis, so that lateral stiffness can be provided in
both directions, particularly in the case of square buildings.
• To avoid torsion effect shear wall should be placed symmetrically about the axis.
39. Function of Shear Wall
The main function of a Shear Wall can be
described as follows.
1. Providing Lateral Strength to building: Shear
Wall must provide lateral shear strength to the
building to resist the horizontal earthquake
forces, wind forces and transfer these forces to
the foundation.
2. Providing Lateral Stiffness to building: Shear
Walls provide large stiffness to building in the
direction of their orientation, which reduces
lateral sway of the building and thus reduces
damage to structure.
40. • Earthquake in general had a long history of deadly
devastations in the past. Earthquakes can be measured
in terms of energy release i.e. measuring amplitude,
frequency, and location of seismic waves and also by
evaluating intensity i.e. considering the destructive
effect of shaking ground on people, structures and
natural features. Basically the response of the structure
due to ground motion is an essential factor to analyze
and design any earthquake resistant structure. The
loads or forces which a structure subjected to
earthquake motions are called upon to resist, the
distortions induced by the motion of the ground on
which it rests.
41. METHODS FOR ANALYSIS
Main aspects of seismic method of analysis based on Indian standard 1893
(Part-1) code “Criteria for Earthquake Resistant Design of Structures” are
Static Analysis and Dynamic Analysis which are described below.
[A] Static Analysis
1. Equivalent Static Method: Seismic analysis of most of the structure are still
carried on the basis of lateral force assumed to be equivalent to actual
dynamic loading. The base shear which is the total horizontal force on the
structure is calculated on the base of structure mass and fundamental
period of vibration and corresponding mode shape. The base shear is
distributed along the height of structure in terms of lateral forces
according to IS 1893 (Part-1) code.
•
42.
43. 2. Push Over Analysis: Non Linear static analysis is the method of seismic
analysis in which performance of the structure is characterized by
capacity curve that represents the relation between the base shear force
and displacement of roof. Analyis is carried out under vertical loads &
gradually increasing lateral loads to estimate deformation and damage
pattern of structure.
44.
45. [B] Dynamic Analysis
1. Response Spectrum Method: The approach permits
the multiple modes of response of a building to be
taken into account. This is required in many building
codes for all except for very simple or very complex
program. The structural response can be defined as a
combination of many modes. Software analysis can be
used to determine these modes for a structure. For
each mode, a response is obtained from the design
spectrum, corresponding to the modal frequency and
modal mass and then they are combined to evaluate
the total response of the structure. In this the
magnitude of forces in all direction is calculated and
then effects on the building is observed.
46.
47. 2. Elastic Time Historey Method: It overcomes all the disadvantages of a response
spectrum analysis, It requires greater computational efforts and mathematical
models using software. It is a step by step analysis of structure to specified loading
that may vary with time.
48. PROCEDURE
A. Effect Of Drift On The Structure:
• In terms of seismic design, lateral deflection and drift can affect both the structural
elements that are part of the lateral force resisting system and structural elements
that are not part of the lateral force resisting system. In terms of the lateral force
resisting system, when the lateral forces are placed on the structure, the structure
responds and moves due to those forces. Consequently, there is a relationship
between the lateral force resisting system and its movement under lateral loads;
this relationship can be analyzed by hand or by computer. Using the results of this
analysis, estimates of other design criteria, such as rotations of joints in eccentric
braced frames and rotations of joints in special moment resisting frames can be
obtained. Similarly, the lateral analysis can also be used and should be used to
estimate the effect of lateral movements on structural elements that are not part
of the lateral force resisting system, such as beams and columns that are not
explicitly considered as being part of the lateral force resisting system.
• Design provisions for moment frame and eccentric braced frame structures have
requirements to ensure the ability of the structure to sustain inelastic rotations
resulting from deformation and drift. Without proper consideration of the
expected movement of the structure, the lateral force resisting system might
experience premature failure and a corresponding loss of strength. In addition, if
the lateral deflections of any structure become too large, P-Δ effects can cause
instability of the structure and potentially result in collapse.
49. B. Seismic weight of building:
• The seismic weight of the building means that is calculated on the
entire floors weight of the building Fundamental Natural period as
per IS 1893(part1):2002
• 1. The approximate fundamental natural period of vibration (Ta)in
seconds of a moment resisting frame building without brick infill
panels may be estimated by the empirical expression
• Ta=0.075h^0.75 for RC framed building Ta=0.075h^0.75 for steel
framed building Where h =height of building
• 2. The approximate fundamental natural period of vibration (Ta) in
seconds, of all other buildings, including moment –resisting frame
buildings with brick infill panels, may be estimated by the empirical
expression:
• Ta= 0.09h/√d
• Where h = height of building d = Base dimensions of the building at
the plinth level in m, along the considered direction of lateral force
50. C. Design Seismic Base Shear:
• The total design lateral force or design seismic base shear
(Vb) along any principal direction shall be determined by
the following expression
• Vb = AhXW
• Where Ah = Design horizontal acceleration spectrum value
as per clause 6.4.2 IS 1893(part1):2002 using the
fundamental natural period Ta as per clause 7.6 IS
1893(part 1):2002 in the consider direction of vibration
• W = Seismic weight of building
• Here Ah = (Z/2)x(I/R)x(Sa/g)
• Z = zone factor I = Importance factor Sa/g = is depending up
on the Ta and type of soil
51. D. Load combination:
• In the limit state design of reinforced and
prestressed concrete structures, the following
load combinations shall be accounted for as
per IS1893 (part1):2002
1. 1.5(DL+IL)
2. 1.2(DL+IL±EL)
3. 1.5(DL±EL)
4. 4 0.9DL±1.5EL
52. ABOUT ETABS
ETABS is an engineering software product that caters
to multi-story building analysis and design. Modeling
tools and templates, code-based load prescriptions,
analysis methods and solution techniques, all
coordinate with the grid-like geometry unique to this
class of structure. Basic or advanced systems under
static or dynamic conditions may be evaluated using
ETABS. For a sophisticated assessment of seismic
performance, modal and direct-integration time-
history analyses may couple with P-Delta and Large
Displacement effects.
53. Loading, Analysis, and Design
• Once modeling is complete, ETABS automatically generates
and assigns code-based loading conditions for gravity,
seismic, wind, and thermal forces. Users may specify an
unlimited number of load cases and combinations.
• Analysis capabilities then offer advanced nonlinear
methods for characterization of static-pushover and
dynamic response. Dynamic considerations may
include modal, response-spectrum, or time-history analysis.
P-delta effect account for geometric nonlinearity.
• Given enveloping specification, design features will
automatically size elements and systems, design reinforcing
schemes, and otherwise optimize the structure according
to desired performance measures.
54. METHODOLOGY AND MODELLING
Initially, an architectural plan is considered that contains
locations of columns which is modeled using ETABS
software considering structural plan of the building with
assumed or appropriate dimensions, Loads are put on the
structure as per IS code, factors like zone factor, importance
factor, response reduction factor play a major role to
determine the value of Base Shear of the structure, Design
check is performed on the structure for the given value of
structural member dimensions, For varying load
combinations as per IS codes once the design check passes
all the members of the structure, equivalent static analysis
is performed resulting in output parameters like storey
drift, storey displacement, storey shear etc.
57. PROCESS OF ETABS
Step - 1: Initial setup of Standard Codes and Country codes
Step - 2: Creation of Grid points & Generation of structure
After getting opened with ETABS we select a new model and a window appears where we had
entered the grid dimensions and Storey dimensions of our building
Step - 3: Defining of property
Here we had first defined the material property by selecting define menu material properties.
We add new material for our structural components (beams, columns, slabs) by giving the specified
details in defining. After that we define section size by selecting frame sections as shown below & added the
required section for beams, columns etc.
Step - 4: Assigning of Property
After defining the property we draw the structural components using command menu.
Draw line for beam for beams and create columns in region for columns by which property assigning
is completed for beams and columns.
58. Step - 5: Assigning of Supports
By keeping the selection at the base of the structure and selecting all the columns we assigned supports
by going to assign menu jointframe Restraints (supports) fixed.
Step - 6: Defining of loads
In ETABS all the load considerations are first defined and then assigned. The loads in ETABS are defined
as using static load cases command in define menu.
Step - 7: Assigning of Dead loads
After defining all the loads. Dead loads are assigned for external walls, internal walls in staad but in
ETABS automatically taken care by the software.
Step - 8: Assigning of Live loads
Live loads are assigned for the entire structure including floor finishing.
Step - 9: Assigning of wind loads
Wind loads are defined and assigned as per IS 875: 1987 PART 3 by giving wind speed and
wind angle.
59. Step - 10: Assigning of Seismic loads
Seismic loads are defined and assigned as per IS 1893: 2002 by giving zone, soil type, and response
reduction factor in X and Y directions.
Step - 11: Assigning of load combinations
Using load combinations command in define menu 1.5 times of dead load and live load will be taken.
Step - 12: Analysis
After the completion of all the above steps we have performed the analysis and checked for errors.
Step - 13: Design
After the completion of analysis we had performed concrete design on the structure as per
IS 456:2000. ETABS performs the design for every structural element
62. Tower Name
Height
m
Master Story Similar To Splice Story
Splice Height
m
Color
T1 Story5 3 Yes None No Blue
T1 Story4 3 No Story5 No Green
T1 Story3 3 No Story5 No Cyan
T1 Story2 3 No Story5 No Red
T1 Story1 3 No Story5 No Magenta
1 Structure Data
This chapter provides model geometry information, including items such as story levels,
point coordinates, and element connectivity.
1.1 Story Data
Table 1.1 - Story Definitions
63. Name Is Auto Load Type Self Weight Multiplier Auto Load
~LLRF Yes Other 0
Dead No Dead 1
EQ X No Seismic 0 IS 1893:2016
EQ Y No Seismic 0 IS 1893:2016
Live No Live 0
W Y No Wind 0 Indian IS875:1987
WX No Wind 0 Indian IS875:1987
2 Loads
This chapter provides loading information as applied to the model.
2.1 Load Patterns
Table 2.1 - Load Pattern Definitions
65. Name Type Notes
Dead Linear Static
Live Linear Static
Modal Modal - Eigen
EQ X Linear Static
EQ X1 Linear Static
EQ Y Linear Static
WX Linear Static
W Y Linear Static
.
2.3 Load Cases
Table 2.3 - Load Case Definitions - Summary
67. Story Diaphragm
Mass X
kg
Mass Y
kg
XCM
m
YCM
m
Cum Mass
X
kg
Cum Mass
Y
kg
XCCM
m
YCCM
m
XCR
m
YCR
m
Story5 D1 84666.56 84666.56 8.5449 3.4504 84666.56 84666.56 8.5449 3.4504
Story4 D1 98600.69 98600.69 8.5621 3.4338 183267.26 183267.26 8.5542 3.4415
Story3 D1 98600.69 98600.69 8.5621 3.4338 281867.95 281867.95 8.557 3.4388
Story2 D1 98600.69 98600.69 8.5621 3.4338 380468.64 380468.64 8.5583 3.4375
Story1 D1 98600.69 98600.69 8.5621 3.4338 479069.34 479069.34 8.5591 3.4367
Table 3.2 - Centers Of Mass And Rigidity
69. Indian IS875:1987 Auto Wind Load Calculation
This calculation presents the automatically generated lateral wind loads
for load pattern WX according to Indian
IS875:1987, as calculated by ETABS.
Exposure Parameters
Exposure From = Diaphragms
Structure Class = Class B
Terrain Category = Category 4
Wind Direction = 0 degrees
70. Basic Wind Speed, Vb [IS Fig. 1]
Vb = 44
meter
sec
Windward Coefficient, Cp,wind Cp,wind = 0.8
Leeward Coefficient, Cp,lee Cp,lee = 0.5
Top Story = Story5
Bottom Story = Base
Include Parapet = No
Factors and Coefficients
Risk Coefficient, k1 [IS 5.3.1]
k1 = 1
Topography Factor, k3 [IS 5.3.3] k3 = 1
Lateral Loading
Design Wind Speed, Vz [IS 5.3] Vz = Vbk1k2k3 Vz = 0
Design Wind Pressure, pz [IS 5.4] pz = 0.6Vz
2
75. IS 1893:2016 Auto Seismic Load Calculation
This calculation presents the automatically generated
lateral seismic loads for load pattern EQ X according to
IS 1893:2016, as calculated by ETABS.
Direction and Eccentricity
Direction = X
Structural Period
Period Calculation Method = Program Calculated
Factors and Coefficients
Seismic Zone Factor, Z [IS Table 3]
Z = 0.36
Response Reduction Factor, R [IS Table 9] R = 5
Importance Factor, I [IS Table 8] I = 1
Site Type [IS Table 1] = II
80. 3-D View Moment 3-3 Diagram (Dead) [kN-m] 3-D View Axial Force Diagram (Dead) [kN]
81. shear force 2-2 diagram (dead) KN 3-D View Moment 3-3 Diagram (Dead) [kN-m]
82. DISCUSSIONS
SOFTSTOREY AND SHEAR WALL
1. Since the behaviour of the soft storey is very different during a
quake, the construction undergoes damage and it increases costs.
For this reason, in regions where the risk of quake is high, we
should not produce soft storeys, if necessary, quake controls should
be done starting from design stage through the stage of occupancy.
2. Present soft storeys should be examined and if necessary, should be
reinforced.
3. Ratios of soft storey irregularities should be taken as SS>0.8-9 and
R>1.5.
4. Soft storey irregularities should be explained so that it would have
the power of sanction
83. 1) The storey displacement of the building with shear wall at corner is least
compared to additional types of models. This is due to as these arrangements
reduce BM concentration. Storey displacement of the structure is also reduced
when we provide shear wall at periphery side but displacement reduction is less
than that of corner.
2) In soft storey structure, the storey drift is utmost at the storey at which the soft
storey level is considered. The storey drift with shear wall at corner is least
compared to other types of models. This is due to the Shear walls acts as a
resistive layer connected to structure. Storey drift is also reduced when we provide
shear wall at periphery side but drift reduction is less than that of corner.
3) The model with shear wall at corner provides max. Base shear when compared with
other models in both cases and in both X-Y directions. SW position will influence
the attraction of forces
4) From the study it has been found that storey stiffness increased when shear walls
are provided at corners when compared to other models. Stiffness is the leading
factor with increase in height of the building. The soft storey gets converted into a
normal storey due shear walls are provided as it increases the horizontal stiffness
and stability of the building structure.
5) From the study it is also seen that by providing shear walls at corners the time
period also get decreases during strong seismic forces.
84. ETABS is a 3D modeling software for any kind of structural analysis and design.
Using this program you can perform both steel structure and RC Structure. Here
are some important advantages of ETABS software for 3D modeling.
ETABS allows user for Graphic input and modification for the sake of easy and
quick model creation for any type of structure.
Creation of 3D model with the utilization of plan views and elevations, 3D model
of any kind of complex structure can be created easily.
With the help of similar storey concept creation of 3D model is very easy and
quicker. If the storey’s are similar then the model generation time can be reduced
multiple time through similar storey concept.
. Creation of object is very quick for any type of object like beam, column, slab,
wall etc. with one click of mouse.
Graphical insertion of sectional dimension of any kind of shape and material
through section designer. Almost all types of shape of various members are
available in this program.
Automatic consideration of self weight of material has made it easy to consider
self weight of various members even the size is changed.
Automatic creation of Earthquake and Wind load saves lots of time to calculate
them manually and assign them in the 3D Model.
Load combination as per your defined building code is also automated; you do not
need to define them individually which save lots of time.
85. MODELING, ANALYSIS AND DESIGN OF SHEAR WALL BUILDING USING STAAD PRO AND REVIT ARCHITECTURE
Mr. M.Siva Chennakesava Rao1, Alluri Rajesh2 ,Desabhathina Naveen3 ,Jonnalagadda Snehanjali4
Kasu Venkata Narendra Reddy5 ,Dudi Mohan Prashant6 ,Kumar Katari Karthik7
Assistant Professor 1,UG Student 2, UG Student 3, UG Student4, UG Student5, UG Student6 UG Student7
Civil Engineering ,
NRI Institute Of Technology , Vijayawada ,India
CONCLUSIONS:
Shear wall building in STAAD PRO
From all the above analysis, it is observed that in 3 story building, constructing building with shear wall in short span at middle I
t is economical as compared with other models. From this it can be concluded that large dimension of shear wall is not effective in
3 stories or below 3 stories buildings. It is observed that the shear wall is economical and effective in high rise building.
Also observed that
1. Changing the position of shear wall will affect the attraction of forces, so that wall must be in proper position.
2. If the dimensions of shear wall are large then major amount of horizontal forces are taken by shear wall.
3. Providing shear walls at adequate locations substantially reduces the displacements due to earthquake.
86. Shear wall building in Revit architecture
This project gives the realistic modelling of building and accurate families ranging from furniture
to lighting fixtures, as well as import existing models from other software’s like Auto CAD etc.
We can get the approximate estimations of building also using Revit Architecture. In this Project we
have done planning, modelling, and we have created families also for this building.
A clear design and modelling of a commercial building with the efficient0structural and architectural plans.
It provides the overall knowledge of material take off in the model of the building defined in the project.
3D realistic view give he clear picture about the family and the components placed with in the building model.
87. Seismic Analysis of Open Ground Storey Building
Akshay S. Paidalwar1 and G.D. Awchat2
1M-Tech Structural Engineering, Department of Civil Engineering, Guru Nanak Institute of Technology, Nagpur, India.
2 Associate Professor, Department of Civil Engineering, Guru Nanak Institute of Technology, Nagpur, India.
CONCLUSIONS
Followings are the salient conclusions obtained from the present study
1. Stiffness of the structure is an important factor in case of OGS type building, in the present study infill
can improve
stiffness of structure but in to some extent, that is not enough to save structure against seismic effect.
2. Problem of OGS buildings cannot be identified properly through elastic analysis as the stiffness of OGS
building and
Bare-frame building are almost same.
RC frame building with open first storeys are known to perform poorly during in strong earthquake shaking.
In this study, the vulnerability of
building with soft storey is shown an example building.
88. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org
IJERTV8IS050115
(This work is licensed under a Creative Commons Attribution 4.0 International License.)
Published by :
www.ijert.org
Vol. 8 Issue 05, May-2019
Seismic Analysis of open Soft Storey Building for Different Models
Pravesh Gairola
Faculty of Technology,
Structural Engineering Department
UTU, Dehradun
Mrs. Sangeeta Dhyani
Faculty of Technology,
Structural Engineering Department
UTU, Dehradun
CONCLUSIONS
From the past earthquakes it has been noticed that the buildings have performed poorly as open storey building.
Hence to understand the behavior of the structure, performance based analysis is very useful. In this project equivalent static
analysis is done for both the structures. All the structures are influenced by dead, live and seismic loads. Out of these three loads,
a seismic
load proves to be major concern. Dead load mostly includes self-weight of the building, while the live load is something we can easily predict
that will come on the structure in its entire lifetime. When it comes to seismic analysis it is very difficult to predict seismic load or rather say that,
the seismic load or earthquake load comes to the structure is highly unpredictable. So to understand the nature of these types of loads seismic
analysis is done using the code recommended i.e. IS 1893:2002.
The values are adopted from the code such that the structure should remain stable during its lifetime against the maximum
considered earthquake on that particular zone. In this project the study is done to achieve an acceptable limit of safety for all structure
so that the structure should not fail to that particular limit. The safety of the structure has always been considered most
important by structural engineer.
89. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 06 | June -2017 www.irjet.net p-ISSN: 2395-0072
Comparing the Effect of Earthquake on Shear wall building and Non-Shear Wall Building – A Review
Mr. Alokkumar A. Mondal1, Mrs. Gitadevi B. Bhaskar2, Miss. Deepa. Telang 3
1M-Tech Student (SE), Department of Civil Engineering, GHRAET, Nagpur, Maharashtra, India
2Assistant Professor, Department of Civil Engineering, GHRAET, Nagpur, Maharashtra, India
3Assistant Professor, H.O.D, Department of Civil Engineering, GHRAET, Nagpur, Maharashtra, India
---------------------------------------------------------------------***---------------------------------------------------------------------
CONCLUSIONS
From the above study it can be concluded that, different researchers had studied different type of problems related to
earthquake and addressed that shear wall are more prominent to resist lateral force due to earthquakes. Analysis by software’s
such as StaddPro, Etabs etc. are also combined along with manual studies. Models are generated and shear walls are located at
different positions in building to find the least displacement of the structure due to shear walls. Openings in shear wall are
also an issue of concern of study of shear wall buildings. Generally openings provided in shear walls increase displacement in
building. Moreover some researches stated that change in positions of shear wall effect the attraction of forces. Location of
shear wall in any building substantially reduces displacements and reduces impact on the structure. Thus building without
shear wall is a subject of concern and need to be retrofitted in places of high earthquake and wind impact.
Future scope of studying this type of research work is an essential part of this review paper. Study of effect of shear wall
building and non-shear wall building can be studied further by introducing a flange to column. Comparison can be made with
a building without shear wall, with shear wall and with column flanges type structure. Moreover placement of shear walls at
different locations is an essential aspect to be thought of for further study.
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