International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 676-683. Article ID: IJCIET_10_04_071
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
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EFFECT OF STIFFNESS OF STAIRCASE, CORE
AND BRICK WALLS IN RC FRAMED
STRUCTURE SUBJECTED TO WIND LOAD
P. Manmanthappa
PG Student Department of Civil Engineering,
Marri Laxman Reddy Institute of Technology & Management, Dundigal, Hyderabad, India
D.SVSMRK. Chekravarty
Associate Professor, Department of Civil Engineering,
Marri Laxman Reddy Institute of Technology & Management, Dundigal, Hyderabad, India.
T. ABHIRAM REDDY
Assistant Professor, Department of Civil Engineering,
Marri Laxman Reddy Institute of Technology & Management, Dundigal, Hyderabad, India
ABSTRACT
Due to excessive displacements of tall buildings occasioned by lateral loads, lateral
load resisting systems are usually provided to curtail the load effect.The resistance may
be offered by Frame Action, Core Walls, or combined Walls and Frames (also known
as Dual System). In this study, 3D structural modeling based software STAAD .Pro V8i
was used to generate and analyze three-dimensional building models for the assessment
of the relative effectiveness of the lateral load resisting systems under the effect of wind.
Ten types of RC frames with and without Staircase and Core wall have been
considered; a bare frame, a frame with external brick wall 230mm & internal brick
wall 115mm thick, a frame with only external brick wall of 230mm thick, a frame with
only external brick wall of 150mm thick and a frame with only external brick wall of
115mm thick.Number of storey has been G+30. Each building model was analyzed for
the determination of the lateral displacements at storey top. From the pilot study, it is
concluded the consideration of stiffness of different elements (i.e., staircase, core and
brick walls) in the frame analysis shows significant variation in the lateral
displacement.
Keywords: STAAD.Pro, Wind load
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P. Manmanthappa, D. SVSMRK. Chekravarty and T. ABHIRAM REDDY
Cite this Article: P. Manmanthappa, D. SVSMRK. Chekravarty and T. ABHIRAM
REDDY, Effect of Stiffness of Staircase, Core and Brick Walls in RC Framed Structure
Subjected to Wind Load, International Journal of Civil Engineering and Technology,
10(4), 2019, pp. 676-683.
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1. INTRODUCTION
In general, as the height of a building increases, its overall response to lateral load (such as
wind and earthquake) increases. When such response becomes sufficiently great such that the
effect of lateral load must be explicitly taken into consideration in design, a multistory building
is said to be tall. Tall buildings are prone to excessive displacements, necessitating the
introduction of special measures to contain these displacements. The lateral load effects on
buildings can be resisted by Frame action, Shear Walls, or Dual System. Peak inter-storey drift
and lateral displacement (or side sway) are two essential parameters used for assessing the
lateral stability and stiffness of lateral force resisting systems of tall buildings. Selection of
such a strong and stiff enough deformation resisting systems that will curtail the drift within
acceptable code limits should be the main motive of structural designers. As it is well known
to most of structural engineers who are familiar with the types of structural systems for resisting
wind and seismic loads, they are called Shear systems.
2. LINEAR STATIC ANALYSIS.
Linear static analysis represents the most basic type of analysis. The term “linear” means that
the computed response displacement or stress, for example is linearly related to the applied
force. The term “static” means that the forces do not vary with time or, that the time variation
is insignificant and can therefore be safely ignored.
What are the assumptions for Linear Static Analysis?
• All loads are applied gradually and slowly until they reach their full magnitude
• After reaching full magnitude the loads remain constant
• Inertial and damping forces to small velocities and accelerations are neglect
Where,
The static analysis equation is: [K]{u} = {f}
K is stiffness,
U is displacement and f is force
2.1. Wind Load
Each wind load is determined by a probabilistic-statistical method based on the concept of
“equivalent static wind load”, on the assumption that structural frames and components /
cladding behave elastically in strong wind.
Usually, mean wind force based on the mean wind speed and fluctuating wind force based
on a fluctuating flow field act on a building. The effect of fluctuating wind force on a building
or part thereof depends not only on the characteristics of fluctuating wind force but also on the
size and vibration characteristics of the building or part thereof. These recommendations
evaluate the maximum loading effect on a building due to fluctuating wind force by a
probabilistic-statistical method, and calculate the static wind load that gives the equivalent
effect. The design wind load can be obtained from the summation of this equivalent static wind
load and the mean wind load
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Effect of Stiffness of Staircase, Core and Brick Walls in RC Framed Structure Subjected to Wind
Load
3. OBJECTIVES OF THE STUDY
The objectives of the present study are as follows:
1. To study the effect of stiffness of staircase, core wall, external brick wall and internal
brick wall on G+30 stored RC space frame structure.
2. To compare the lateral displacement among all the considered R.C Space fram
3.1. Scope of the Work:
•
This study is made for G+30 storied structures with plan dimensions of 60.10m
x19.23m.
• The column and the floor beam sizes are maintained uniform for the frame.
• The beams and columns are modeled with member element and the base of the structure
is considered as fixed.
• The Brick wall walls are modeled with plate element.
• Linear static analysis was done on the structures.
Designs are carried out using IS: 456:2000 in STAAD.proV8i
Table 3.1 Section details
MEMBER
Plinth Beams
Floor & Roof Beams
Columns
External Walls
Internal Walls
Slab
SIZE (mm)
230 X 300
300 X 600
450 X 1200
230, 150 & 115
115
150
4. LOADS
Following loads used for analysis
• Dead Load (IS 875 –part I)
• Live Load (IS 875 – part II)
• Wind Load (IS 875 –part III)
Refer appendix –I for detailed Load calculations.
4.1. Load combinations
Following load combinations were considered for limit state of serviceability as per IS.875
(Part V)
1. D.L+L.L
4. D.L+W.L.-Z
7. 0.75(D.L+L.L+W.L.-Z)
2. D.L+W.L.X
5. 0.75(D.L+L.L+W.L.X)
8. D.L+W.L.Z
3. D.L+W.L.-X
6. 0.75(D.L+L.L+W.L.-X)
9. 0.75(D.L+L.L+W.L.Z)
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P. Manmanthappa, D. SVSMRK. Chekravarty and T. ABHIRAM REDDY
4.1.1. Plan of Building
4.1.2. General Consideration
• Analyzed for G+30 storey structure with a 57.52m x 19.56m plan area.
• Ten types of RC space frames analyzed with and without Staircase and Core wall
having different thickness of Brick wall walls.
• Considered under permanent vertical loads and Wind load (basic wind speed44m/s).
4.2. R.C Framed Structures with different Stiffness configurations as follows:
4.2.1. Case 1: Bare Frame
• The columns are of 450mm x 1200mm size, plinth beams are of 230mm x300mm, floor
& roof beams are 300 x600mm and size150mm thick Slab is considered on the all floors
&Roof.
• The loads acting on the structure are assigned. Here self weight, live load, wall loads,
slabs Loads and Wind loads are considered.
• Then the structure is analyzed for linear static analysis.
Figure 4.1 Front view of Bare Frame
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Figure 4.2 3D-view of Bare Frame
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Effect of Stiffness of Staircase, Core and Brick Walls in RC Framed Structure Subjected to Wind
Load
Figure 4.3 Lateral Displacement Vs Height for Bare frame
From Fig 4.3, observed that the maximum displacement of 726.714mm occurs at top storey
(i.e., 93m level) and it’s not satisfied the requirement of permissible lateral displacement (i.e.,
H/500, H = Height of structure) as per IS 456:2000.
4.2.2. Case 2: Frame with External brick wall 230mm and internal brick wall115mm
The columns are of 450mm x 1200mm size, plinth beams are of 300mm x300mm, floor & roof
beams are 300 x600mm and size150mm thick Slab is considered on the all floors &Roof
Figure 4.4 Lateral Displacement Vs Height for frame with External & Internal brick wall of 230mm
& 115mm thick
From Fig 4.4, observed that the maximum displacement of 101.816mm occurs at top storey
(i.e., 93m level) and it’s satisfied the requirement of permissible lateral displacement (i.e.,
H/500, H = Height of structure) as per IS 456:2000.
4.2.3. Case 3: Frame with only External brick wall of 230mmthick
The columns are of 450mm x 1200mm size, plinth beams are of 300mm x300mm, floor & roof
beams are 300 x600mm and size150mm thick Slab is considered on the all floors &Roof.
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P. Manmanthappa, D. SVSMRK. Chekravarty and T. ABHIRAM REDDY
Figure 4.5 Lateral Displacement Vs Height for frame with only External brick wall of 230mm thick
4.2.4. Case 4: Frame with only External brick wall of 150mmthick
Figure 4.15 Comparison of Lateral displacement Vs Height for Bare frame (RF1) and Frame with
Staircase & Core Wall External brick wall of 230mm thick (RFSC3)
From Table.4.5.1, observed that, there is a reduction in percentage of variation in lateral
displacement of 87.24 % at top storey, while comparing with the bare frame.
4.3. COMPARISON III
Table 4.3 Comparison between Bare Frame (RF1) and Frame with Staircase, Core wall & External
brick wall 230mm (RFSC3)
Type of Structure
Bare Frame (RF1)
Frame with staircase, core wall
and only external brick wall
230mm (RFSC3)
Permissible Percentage of Variation
Max. Lateral
Lateral
in Lateral Displacement
Displacement
Displacement
((RF1(mm)
(mm)
RFSC3)/RF1))X100
726.714
186
96.749
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87.24
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Effect of Stiffness of Staircase, Core and Brick Walls in RC Framed Structure Subjected to Wind
Load
Figure 4.15 Comparison of Lateral displacement Vs Height for Bare frame (RF1) and Frame with
Staircase & Core Wall External brick wall of 230mm thick (RFSC3)
From Table.4.5.1, observed that, there is a reduction in percentage of variation in lateral
displacement of 87.24 % at top storey, while comparing with the bare frame.
5. CONCLUSIONS
The lateral displacement of R.C framed structure with and without considering Staircase, Core
wall &brick walls was investigated using the linear static analysis. Following were the major
conclusions drawn from the study.
1. The lateral displacement in Bare frame (RF1) is the greatest among the ten lateral load
resisting systems investigated.
2. In all the options the values of story lateral displacements are within the permissible
limits as per code limits except Bare Frame (RF1) and Frame with staircase & core wall
(RFSC1). However, it is observed that there was a considerable variation in the lateral
displacement of frame with staircase & core wall while compared with bare frame.
3. There is a reduction in percentage of variation in later displacement of 86.45% at top
storey (i.e., 93m level), when compared to bare frame (RF1) to frame with staircase,
core wall and external brick wall 230mm(RFSC3).
4. It is concluded consideration of stiffness of different elements (i.e., staircase, core and
brick wall walls) in the frame analysis shows significant variation in the lateral
displacement.
5.1. Scope of further study
1. In this thesis, studied the effect of stiffness of various structural elements for wind loads
only, can also study the effect of stiffness for seismic load.
2. The similar study can be carried out for different geometries of high-rise buildings.
3. The same study can be carried out by Non- linear static analysis.
6. LOAD CALCULATIONS
6.1. Dead load
1. Self weight of beams and columns
2. Self weight of walls
a. External walls
=0.23x2.55x16
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=9.4kN/m
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P. Manmanthappa, D. SVSMRK. Chekravarty and T. ABHIRAM REDDY
b. Internal walls
=0.115x2.55x16
=4.7kN/m
c. Parapet wall
=0.115x1.2x16
=2.2kN/m
3. Self weight of slab =0.15x1x25 =3.75kN/m2
a. Floor finish (including mortar)
=0.75kN/m2
b. (assume) Unexpected partition (unknown force)
=1.0kN/m2
2
c. (assume) Total load on slab
=5.5kN/m
4. Load on staircase
=14kN/m
6.2. Live load
1. All internal room
=2kN/m2
2. Staircase
=3kN/m2
3. Corridor
=3kN/m2
6.3. Wind Load Calculations Basic data
1. Wind Speed (Vb =m/s)
: 44 m/s for Hyderabad
2. City Terrain Category
II
3. Structure Class
: B Risk Coefficient Factor (K1 ) :1.00
Topography Factor (K3 ) : 1 for slope < 3 degree
Where
Vb = m/s basic wind speed for Hyderabad city (as per IS 875-part-3, p-53,
Appendix A, fig-1 p-9)
K1 = 1.00 Probability factor (risk coefficient) (clause 5.3.1) (as per IS 875-part-3, p-11,
table-1)
K2 = 1.63 Terrain, Height and Structure size factor ( as per IS 875-part-3, p-12, table-2 )
(Clause =5.3.2.2 ) ( terrain category -2, class – c , height – 93 m ), and
K3 = 1.00, Topography Factor for slope < 3 degree
H is the height structure,
l is the greater horizontal dimension of a building and w is the lesser horizontal dimension
of a building.
REFERENCES
[1]
[2]
[3]
[4]
[5]
ASCE 7-02, “Minimum Design Loads for Buildings and Other Structures”, American
Society of Civil Engineers, New York,2002.
Bungle S. Taranath, ―“wind and earthquake resistant buildings structural analysis and
design”, CRC Press, Series Editor: Michael D. Meyer. Developed as a resource for
practicing engineers.
Danish, M., Masood, S., Masood, A. and Shariq, M (2013), “Seismic Behaviour of
Masonry Brick walls Reinforced Concrete Building”, International Conference on
Innovation in Concrete Construction, UKERI Concrete congress,2169-2191.
Dr. D.R.Panchal and Dr. S.C.Patodi, “Response of a Steel Concrete Composite Building
Vis-a-Vis and R.C.C. Building under Seismic Forces”, NBM & CW journal, AUGUST
2010.
IS 456:2000, “Indian Standard plain and reinforced concrete-Code of Practice”, Bureau
of Indian Standards, New Delhi,2000.
IS: 875 (Part 1), “Indian Standard Code of Practice for design loads for building and
structures, Dead Loads” Bureau of Indian Standards, New Delhi
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