Download effect of opening on behaviour of shear wall

International Journal For Technological Research In Engineering
Volume 3, Issue 4, December-2015
ISSN (Online): 2347 - 4718
EFFECT OF OPENING ON BEHAVIOUR OF SHEAR WALL
Bhruguli H. Gandhi
Abstract: Finite Element modellingnow days is an essential
approach in analysing and simulating civil engineering
problem numerically. In this paper attempt is made to apply
the finite element modelling in analysing and exploring the
behavior of shear wall with opening under seismic load
actions. In modern tall buildings, shear walls are commonly
used as a vertical structural element for resisting the lateral
loads that may be induced by the effect of wind and
earthquakes. Shear walls are generally located at the sides
of buildings or arranged in the form of core that houses
stairs and lifts. Due to functional requirements such as
doors, windows, and other openings, a shear wall in a
building contains many openings. The size and location of
openings may vary from architectural and functional point
of view. In most of the apartment building, size and location
of openings in shear wall are made without considering its
effect on structural behavior of the building. This study is
carried out on 6- story frame-shear wall buildings, using
linear elastic analysis with the help of finite element
software, STAAD PRO under earthquake loads in
equivalent static analysis. The results reveal that stiffness as
well as seismic responses of structures is affected by the size
of the openings as well as their locations in shear wall. It is
also explored that top lateral drift of the system can also be
reduced thickening the element in the model around the
opening of shear wall
Keyword: Shearwall,
I. INTRODUCTION
Shear wall are specially designed structural walls in building
to resist lateral forces that are produce in the plane of wall
due to wind, earthquack and other forces. Shear wall is
normally behaves like a flexural member. In a tall building
use of shear wall avoids total collapse of buildings under
seismic forces.The lateral and gravity load-resisting system
consists of reinforced concrete walls and reinforced concrete
slabs. Shear walls are the main vertical structural elements
with a dual role of resisting both the gravity and lateral loads.
Wall thickness varies from 140 mm to 500 mm, depending
on the number of stories, building age, and thermal insulation
requirements. In general, these walls are continuous
throughout the building height; however, some walls are
discontinued at the street front or basement level to allow for
commercial or parking spaces.
II. SHEARWALL BUILDING
Reinforced concrete (RC) buildings often havevertical platelike RC walls called Shear Walls in addition to slabs, beams
and columns. These wallsgenerally start at foundation level
and are continuousthroughout the building height. Their
thickness can beas low as 150mm, or as high as 400mm in
high risebuildings. Shear walls are usually provided along
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bothlength and width of buildings. Shear wallsare like
vertically-oriented wide beams that carryearthquake loads
downwards to the foundation.
Advantages of Shear Walls in RC Buildings
Properly designed and detailed buildings with shear walls
have shown very good performance in past earthquakes. The
overwhelming success of buildings with shear walls in
resisting strong earthquakes is summarised in the quote: “We
cannot afford to build concrete buildings meant to resist
severe earthquakes without shear walls”:: Mark Fintel, a
noted consulting engineer in USA. Shear walls in high
seismic regions require special detailing. However, in past
earthquakes, even buildings with sufficient amount of walls
that were not specially detailed for seismic performance (but
had enough well-distributed reinforcement) were saved from
collapse. Shear wall buildings are a popular choice in many
earthquake prone countries, like Chile, New Zealand and
USA. Shear walls are easy to construct, because
reinforcement detailing of walls is relatively straight-forward
and therefore easily implemented at site. Shear walls are
efficient, both in terms of construction cost and effectiveness
in minimizing earthquake damage in structural and nonstructural elements (like glass windows and building
contents).
Architectural Aspects of Shear Walls
Most RC buildings with shear walls also havecolumns; these
columns primarily carry gravity loads(i.e., those due to selfweight and contents of building).Shear walls provide large
strength and stiffness tobuildings in the direction of their
orientation, whichsignificantly reduces lateral sway of the
building andthereby reduces damage to structure and its
contents. Since shear walls carry large horizontal
earthquakeforces, the overturning effects on them are large.
Thus,design of their foundations requires special attention.
Ductile Design of Shear Walls
Just like reinforced concrete (RC) beams andcolumns, RC
shear walls also perform much better ifdesigned to be
ductile. Overall geometric proportionsof the wall, types and
amount of reinforcement, andconnection with remaining
elements in the buildinghelp in improving the ductility of
walls. The IndianStandard Ductile Detailing Code for RC
members(IS:13920-1993) provides special design guidelines
forductile detailing of shear walls.
Overall Geometry of Walls:
Shear walls areoblong in cross-section, i.e., one dimension of
thecross-section is much larger than the other.
Whilerectangular cross-section is common, L- and U-shaped
sections are also used. Thin-walled hollowRC shafts around
Copyright 2015.All rights reserved.
875
International Journal For Technological Research In Engineering
Volume 3, Issue 4, December-2015
the elevator core of buildings alsoact as shear walls, and
should be taken advantage of toresist earthquake forces.
ISSN (Online): 2347 - 4718
Frame (100% opening)
Reinforcement Bars in RC Walls:
Steelreinforcing bars are to be provided in walls inregularly
spaced vertical and horizontal grids. The vertical and
horizontal reinforcement in thewall can be placed in one or
twoparallel layers calledcurtains. Horizontal reinforcement
needs to beanchored at the ends of walls. The minimum area
ofreinforcing steel to be provided is 0.0025 times thecrosssectional area, along each of the horizontal andvertical
directions. This vertical reinforcement shouldbe distributed
uniformly across the wall cross-section.
Boundary Elements:
Under the large overturningeffects caused by horizontal
earthquake forces, edgesof shear walls experience high
compressive and tensilestresses. To ensure that shear walls
behave in a ductileway, concrete in the wall end regions must
bereinforced in a special manner tosustain these loadreversals
without losing strength. Endregions of a wall with increased
confinement are calledboundary elements. This special
confining transversereinforcement in boundary elements is
similar to thatprovided in columns of RC frames. Sometimes,
thethickness of theshear wall in these boundary elements is
alsoincreased. RC walls with boundary elements
havesubstantially
higher
bending
strength
and
horizontalshear force carrying capacity, and are therefore
lesssusceptible to earthquake damage than walls without
boundary elements.
Design and Analysis Data:
Size of wall
Span :6 meter
Height of each floor :3
meter
No of Floor :5 no
Plate thickness: 0.15m
Size of Frame
Beam (R1): 0.3 m * 0.45m
Column(R2):0.6m * 0.3m
Material used
: Concrete
Forces at each floor 1st floor : Fx = 56 kN
: (from G.L)
2nd floor : Fx = 224 kN
3rd floor : Fx = 504 kN
4th floor : Fx = 896 kN
5th floor : Fx = 1000 kN
Support at base
Fixed
Fixed
STAAD PRO
Cases:
Solid wall (0% opening)
Concentric opening
 20% opening
 40% opening
 50% opening
 60% opening
Eccentrics opening (20% opening)
 Straight opening
 Zigzag opening
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Copyright 2015.All rights reserved.
876
International Journal For Technological Research In Engineering
Volume 3, Issue 4, December-2015
ISSN (Online): 2347 - 4718
Deflection in X direction and % of deflection at different node point
As we see Graph-1, is node vs % deflection for straight
opening. Graph shows as % of opening increases deflection
increases up to 40% in proportion but after that as % of
opening increases deflection increases more rapidly. As we
see Graph-2 is node vs % deflection for 20% concentric,
eccentric, and zigzag pattern. In this 20% opening Eccentric
zigzag has lesser deflection and Eccentric Straight has
maximum deflection and concentric loading has less
deflection than Eccentric Straight.
As we see the graph -4 is % opening vs stresses around
opening in the shear wall. Till the 40% opening stress around
the opening is increasing proportionally after that if we
provide 50% opening stress around opening is increasing
drastically.





As we see the graph -3 is % opening vs bottom stress in the
shear wall. Till the 40% opening bottom stress is increasing
proportionally after that if we provide 50% opening bottom
stress is increasing drastically.
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[1]
III. CONCLUSION
As we see in the Graph-1 ,% of opening increases
deflection increases up to 40% in proportion but
after that as % of opening increases deflection
increases more rapidly
As per Graph-2 for 20% opening Eccentric zigzag
has lesser deflection and Eccentric Straight has
maximum deflection and concentric loading has less
deflection than Eccentric Straight
As per Graph-3 as opening increases bottom
Stresses also increases proportionally up to 40%
then after Stresses increases vastly.
Graph-4 shows Stresses around opening, for
different opening condition. We can directly judge
that after 40% stresses increases more rapidly
So, for a given loading up to 40% opening is
suitable for shear wall though code says provide
opening as per necessity.
REFERENCES
Can Balkaya, M.ASCE,1 and ErolKalkan,
S.M.ASCE2
“Three-Dimensional Effects on
Openings of Laterally Loaded Pierced Shear
Copyright 2015.All rights reserved.
877
International Journal For Technological Research In Engineering
Volume 3, Issue 4, December-2015
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ISSN (Online): 2347 - 4718
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Daniel Carroll, James Loney, Brian Keating,
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Structural Analysis Lab
Muhammed Abbas Husain “Analysis of Shear Wall
with Openings using Brick Element” European
Journal of Scientific Research,2011
Ardeshir DEYLAMI1 And Hossein DAFTARI2, “
NON-LINEAR BEHAVIOR OF STEEL PLATE
SHEAR WALL WITH LARGERECTANGULAR
OPENING”,12th WCEE,2000
Fernando Yáñez1, Maximiliano Astroza2, Augusto
Holmberg3, Oscar Ogaz4, “BEHAVIOR OF
CONFINED MASONRY SHEAR WALLS WITH
LARGE OPENINGS”,13th WCEE,2004
IS code:456, IS:13920
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