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Shear Wall Construction in Buildings

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Shear Wall Construction in Buildings: A Conceptual Framework on the Aspect
of Analysis and Design
Article in Applied Mechanics and Materials · December 2012
DOI: 10.4028/www.scientific.net/AMM.268-270.706
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Applied Mechanics and Materials Vols. 268-270 (2013) pp 706-711
© (2013) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMM.268-270.706
Shear Wall Construction in Buildings: A Conceptual
Framework on the Aspect of Analysis and Design
Muhammad Abu Eusuf Ph. D1, a & Khairuddin A. Rashid, Ph. D2, b,
Wira Mohd. Noor, Ph. D3, c and Abdullah Al Hasan4, d
1, 2
Faculty of Architecture and Environmental Design, International Islamic University Malaysia
3
Faculty of Engineering, International Islamic University Malaysia
4
Post-graduate Student, Built Environment, International Islamic University Malaysia
a
[email protected]/ [email protected], [email protected],
c
[email protected], [email protected]
Keywords: shear stress, shear wall, lateral forces, wind and earthquake prone areas, high-rise
building.
Abstract: This study describes the analysis and design process of shear wall construction, which is
applied in various types of building construction. Shear walls resist lateral forces viz. earthquake
force and wind force for high-rise structure and gravity load for all type of structure. Besides,
Buildings with cast-in-situ reinforced concrete shear walls are widely used in earthquake-prone area
and regions in the world. Research methods were confined to library research and employed
software for analysis. The analytical accuracy of complex shear wall system have always been of
concern to the civil and structural Engineering system. The software of this system is performed on
the platform of modelling and then, the system models are usually idealized as line elements instead
of continuum elements. Single walls are modelled as cantilevers and walls with openings are
modelled as pier/ spandrel systems. In order to find the stiffness, the simple systems models can
provide reasonable results. It has always been accepted that a scale based model in the FEM is exact
and justifiable.
Introduction
Shear walls are vertical elements of the horizontal force resisting system; they can resist forces
directed along the length of the wall. Once shear walls are designed and constructed properly, they
will have the strength and stiffness to resist the horizontal forces [1]. It is well known to civil and
structural engineering system that the key purpose of all kinds of structural systems used in building
structures or any infrastructure is to support gravity loads, the most common loads resulting from
the effect of gravity are dead load, imposed live load and climatic snow load. Besides these loads,
buildings and any other high-rise structures are also subjected to lateral loads caused by wind;
blasting or earthquake and hydrostatic load (refer to Fig. 1). Lateral loads can develop high stresses,
produce sway movement or cause vibration [7]. Therefore, it is very important for the structure to
have sufficient strength against vertical loads together with adequate stiffness to resist lateral forces.
Shear resist mainly two types forces such as shear and uplift forces.
Recently, significant figures of high-rise buildings have reinforced concrete structural
systems. This is due to economic reasons. Reinforced concrete building structures can be classified
as follows [8] (refer to Table 1.1).
Table 1.1: Reinforced Concrete Building Structures
No.
1
2
3
Systems
Structural Frame
Systems
Structural Wall
Systems
Shear Wall–Frame
Systems (Dual system)
Description
Loading system
Basic elements of structural system
• Frames; Floor Slab; Beams; Columns
All vertical members are analyzed, design
and construction as structural wall, known as
shear wall.
The system consists of reinforced concrete
(RC) frames interacting with RC shear walls.
• Carrying gravity load, while
providing adequate
• Carrying gravity load, lateral
load such as wind and
earthquake load.
• Resist gravity load and lateral
load
Source: [8]
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
www.ttp.net. (ID: 210.48.222.12-22/11/12,07:08:12)
Applied Mechanics and Materials Vols. 268-270
Figure 1: Schematic diagram for force developed by earth
quake
707
A render view of 3D high-rise
building has been given in Fig.
2 and a typical floor plan of a
shear
wall-frame
building
structure is given in Fig. 3. It is
a fact that shear walls have high
lateral resistance. In a shear
wall-frame
system,
this
advantage can be used by
placing
shear
walls
at
convenient locations in the plan
of the building [9].
Load Sources
The major types and sources of loads acted on building structures are given in the above Table 1.2.
Table 1.2: List loads with sources
Loads and Sources
Determination
Application
No.
1
2
Gravity: weight of
• the structural
components of the
building;
• occupants and content;
• snow, ice or water on
roof
Wind: Moving air; In
fluid- flow action.
3
Earth quake (Seismic
Shock): Shaking of the
ground as result of large
subterranean faults,
volcanic eruptions or
underground explosions.
4
Hydrostatic pressure:
Principally from ground
water when the free level
is above the bottom of the
basement.
Soil pressure (active):
Action of soil as a semifluid on objects buried in
the ground.
Thermal Change:
Temperature variations in
the building from
fluctuations in outdoor
temperature and
temperature differences.
5
6
By determination of• Volume;
• Density; and
• Types of dispersion
Anticipated
maximum
wind
velocities established by local
weather history. The wind loading
is the most important factor that
determines the design of tall
buildings over 10 storeys, where
storey height about lies between 2.7
– 3.0m.
• By prediction of the probability
of occurrence on the basis of
history of the region and records
of previous seismic activities;
• Principal force effect is the
horizontally impelled inertial
action to the building mass.
As fluid pressure proportional to
the depth of the fluid.
Usually by considering the soil as
an equivalent fluid with a fluid
density some fraction of the true
soil density.
• From weather histories;
• Internal design temperature; and
• Coefficients of expansion of the
materials
• Vertically downward;
• Constant in magnitude.
• As pressure (Perpendicular to the
surface);
• As Frictional drag (parallel to the
surface);
• As an overall horizontal force effect
on the building;
• Any surface may be affected in
relation to its own individual
geometry or orientation.
• Back and forth, up and down
movement of the supporting ground;
• Response of the building structure on
the basis of its own dynamic
properties.
• As horizontal pressure on walls;
• Upward pressure on floors
Horizontal pressure on walls.
• Forces exerted on structure if free
expansion is restrained;
• Distortions and stresses within
structure if connected parts differ in
temperature
708
Materials, Mechanical Engineering and Manufacture
8
9
Shrinkage: Volume
reduction
Vibration
Internal Action
10
Handling
7
• concrete; mortar joints in masonry; large unseasoned timber;
• May produce forces similar to those caused by thermal effects.
It may be caused by heavy machinery, vehicles or high- intensity sounds.
Forces may induced by the settling of supports, slippage or loosening of
connections, warping of elements, and so on.
Forces are exerted on structural elements during production, erection,
transportation, storage, remodelling, and so on. These effects are not
necessarily evident in the form of finished building, but must considered in it
production.
Source: [2], [3], [4], [5], [6]
Characteristics Load and design load
The characteristics or service load is the actual load that the structure is designed to carry.
These are normally considered as the maximum loads which will not be exceeded during the life of
the structure. In statistically, the characteristic load has a 95% probability of not being exceeded [2].
The characteristic loads used in design and defined in BS8110: Part 1, clause 2.4.1, is as follows:
a)
b)
c)
d)
The characteristic Dead Load (Gravity load)
The characteristic Imposed load
The Wind Load
The earth quake loads
Design load is the product of characteristic load and partial safety factor. The partial safety
factor (given in BS8110: part 1) in Table 1.3 takes account of Possible increases in load; inaccurate
assessment of the effects of loads; unseen stress distributions in members; importance of the limit
state being considered.
Table 1.3: Load Combination process
No.
Load Combinations
Dead load
Adverse Beneficial
1
2
3
Dead and imposed load (and
earth and water pressure)
Dead and wind (and earth and
water pressure)
Dead, wind and imposed (and
earth and water pressure)
Load Types
Imposed Load
Adverse
Beneficial
Earth and
Hydrostatic
pressure
0.0
1.4
-
-
1.4
1.4
1.2
1.2
1.2
1.4
1.0
1.6
1.4
1.0
-
1.2
1.2
1.2
Wind
Source: [2], [6]
Location of Shear Wall
Shear walls should be located on each level of the structure. It should be added to the
building interior when the exterior walls cannot provide sufficient strength and stiffness or when the
allowable span-width ratio for the floor or roof diaphragm is exceeded. For subfloors with
conventional diagonal casing, the span-width ratio is 3:1.
Shear walls are most efficient when they align vertically and are supported on foundation
walls or footings. When shear walls do not align, other parts of the building will need additional
strengthening. Consider the common case of an interior wall supported by a subfloor over a crawl
space and there is no continuous footing beneath the wall. For this wall to be used as shear wall, the
subfloor and its connections will have to be strengthened near the wall [2].
Shear walls carry the adequate lateral strength to resist incoming horizontal earthquake
forces. When shear walls are well-built, they easily transfer the horizontal force to the next elements
of load path below the shear walls. The next elements in the load path may be considered as
another shear walls, floors, foundation walls, slabs or footings.
Applied Mechanics and Materials Vols. 268-270
709
The strength of the shear wall depends on the combined strengths of its 3-components: solid
wall; casing or sheathing and fastener. Strength can be reduced due to the improper installation.
Fasteners for shear wall construction may be staples, screws or nails.
Procedure on the Analysis and Design of Shear Wall
A concept has been developed on the analysis and design of shear wall, which has been given in
the following as procedure. The procedure follows some steps [7].
Step-1: Evaluate the behaviour of shear wall structures
i) Lengths and thickness may change, or discontinued, at stages up the height. The effects
of variation can create a complex redistribution of the moment and shears between the
walls.
ii) Categories shear wall is as proportionate. Non-proportionate system is statically
indeterminate.
a)
3.5m
3.5m
3.5m
3.5m
b)
Figure 2: 3-D High-rise render view Figure 3: Typical Floor Plan with Shear Wall - Frame
A typical framed structure braced Building Structure-a) Schematically presents, b) by
STRUDS (a structural analysis and design software)
with core wall.
Step-2: Analysis of Proportionate system: the system is statically determinate and then categories
into ‘structure twist and non twist.
710
Materials, Mechanical Engineering and Manufacture
i) Proportionate non twisting structures: A structure that is symmetrical on plan about the axis
of loading.
(1)
; i= level; j= wall, EI = flexural rigidity
(2)
ii) Proportionate twisting structures: A structure that is not symmetrical on plan about the axis
of loading will generally twist as well as translate and twists under the action of horizontal
load the resulting horizontal displacement of any floor is combination of translation and
rotation of floor about the a centre of twist.
(3)
Step- 3: Analysis of non proportionate system: non-proportionate structures consist of walls whose
flexural rigidity ratios are not constant throughout height, and that have different load- deflection
characteristics.
i) Non-proportionate non twisting structures
ii) Non-proportionate twisting structures
Step-4: Stress Analysis: If the wall is rectangular in elevation and has a height to width ratio greater
than 5, a close estimate of the axial stresses is given by simple bending theory. If aspect ratio is less
than 5:1, or if it is irregular with changes in width or openings or beam or other walls connects to it,
a more detail analysis is necessary.
i) Membrane finite element analysis
ii) Analogous frame analysis: a) Braced frame analogy; b) axial, shear and bending
stiffness; c) Application of analogous frame; d) Conversion of analogous frame forces to
wall stresses
Step-5: Concrete shear wall: It may be cast-inplace or pre-cast. Pre-cast panel walls are also
used within a concrete or steel frame to
provide lateral resistance. Coupling beams
should have diagonal reinforcement to develop
shear resistance.
Figure 3 (opposite): A typical floor plan of
shear wall buildings in European perspectives
(WHE report).
Conclusions
The lateral loads or horizontal loads are assumed to be concentrated at the floor levels. The
rigid floors stretch these loads to the columns or walls in the building. On the other hand, lateral
loads are particularly large in case of high-rise buildings or when earthquake loads are considered.
To mitigate or resist the large part of lateral loads, it is recommended to design reinforced concrete
walls parallel to the directions of load. The lateral loads caused by wind or earthquakes act as deep
Applied Mechanics and Materials Vols. 268-270
711
cantilever beams fixed at foundation system. Repeatedly, buildings have interior concrete core walls
in the region of the elevator, stair case, service wells as underground water reservoir & overhead
reservoir and other circulation area. There are multi-dimensional advantages of shear walls such asa) the high level of rigidness in their own plane easily can limit the adverse deflection effectively;
b) act as fire compartment walls; c) ability to resist lateral wind effect at super-structure and earth
motion effect in the sub- structure.
However, for low and medium rise buildings (less than 10-storeys), the construction of shear
walls are more time consuming and less accurate in dimensions than steelwork. Generally, RC walls
acquire satisfactory strength and stiffness to resist the lateral loading system. Shear walls comprise
minor ductility and may not meet the energy required under severe earthquake. Care should be
taken in the design of ductile shear walls which are used to resist earthquake loads. 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.
References
[1] Ashraf Habibullah , S.E. Physical Object Based Analysis and Design Modelling of Shear Wall
Systems Using Etabs, Computers & Structures, Inc., Berkeley, California (2003)
[2] Bhatt P., Macginley T. J. and choo B. S. Reinforced Concrete: Design theory and examples,
Taylor and Francis (2006)
[3] British Standard, loading for buildings (LFB), BS6399-1:Part-1: code of practice for dead and
imposed load (1996)
[4] British Standard, loading for buildings,BS6399-2:Part-2: code of practice for wind load (1997)
[5] British Standard, LFB, BS6399-3:Part-3: code of practice for imposed roof load (1988)
[6] Mendis P., Ngo T., Haritos N., Hira A., Samali B. and Cheung J. Wind Loading on Tall
Buildings, E. Journal of Structural Engineering: loading on structure (2007)
[7] Smith B. S and Couli Alex. Tall Building Structures: Analysis and Design, John Wiley & Sons,
inc (1991)
[8] Taranath, B.S. Structural Analysis and Design of Tall Buildings, McGraw-Hill Company(1998)
[9] Tolga Aki ¸S. Lateral Load Analysis of Shear Wall-Frame Structures, Ph. D Thesis, The
Graduate School of Natural and Applied Sciences of Middle East Technical University (2004)
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