Analysis of cylindrical shell structure with varying parameters

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 05 | May-2015, Available @ http://www.ijret.org 141
ANALYSIS OF CYLINDRICAL SHELL STRUCTURE WITH VARYING
PARAMETERS
Nilesh S. Lende1
, Rajshekhar S. Talikoti2
1
PG student, Department of Civil Engineering, Late G. N. Sapkal College of Engineering, Anjaneri Nashik-422413,
Affiliated to Pune University, India.
2
Professor & Head, Department of Civil Engineering, Late G. N. Sapkal College of Engineering, Anjaneri Nashik-
422413, Affiliated to Pune University, India.
Abstract
The shell structures are composed of a thin shell made of reinforced concrete without the use of internal columns giving an open
interior. Most common shells used in industry are flat plates and domes but different shapes like cylindrical, parabolic or
spherical section may also used. Sports or storage facilities buildings are common concrete shell structures. However, they can be
difficult to design, as the exact shape required for stability of structure depends on the material used, the size of the shell, exterior
or interior loading, and other oblique. So by varying the parameter of the shell, behaviour of the shell is also varying. Main goal
of this paper is parametric analysis of the multiple cylindrical shell structures with different lengths. For analysis we took two
different lengths of cylindrical shell and then, two parameters have been change first one is radius and second is thickness, on the
basis of different radius and thickness for same chord width, length, and material of shell we will compare the behaviour of shell
for different models.
Keywords: Multiple cylindrical shells, Analysis, Different Parameter.
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1. INTRODUCTION
The reinforced concrete shells can be defined as curved
shape slabs whose thickness is very small compared to their
other dimensions. The curved structures resisted more
applied forces than flat plate with less deformation and
stresses. Also shell structure are much efficient than other
structure having the same span and dimensions because
there shapes have a high strength to weight ratio. There are
a different type of shell depend upon their size, shape, type
of load, material used etc. Due to this large variation, many
practical difficulties were occurring. To solve these
difficulties many researchers introduced their theory for
design of shell. The common type of shell used in field is
cylindrical reinforced concrete shell to cover large space.
Generally long shells and short shells are the two different
form of cylindrical shell. Normally long shells are used for
roof factories and short shells for aircraft hangers.
In this paper we use thin reinforced concrete long
cylindrical shell for analysis. Membrane analysis of circular
cylindrical shells is very easy. For bending analysis of these
shells, various researchers have presented different methods
and equations. And these equations are very useful for
deriving computer based solutions. The ASCE, manual 31
on design of concrete shell roofs method presents a method
similar to that we are familiar with and use for elementary
analysis of indeterminate structure in theory of structures. It
will give us a good idea of the nature of the forces in these
shells so that when we use the modern computer software,
we can have a better awareness of the output. But the
ASCE manual 31 tables are restricted to be used for limited
shell dimensions only. Due to these restrictions we should
always plan shells in such a way that their dimensions suit
the tables of manual no. 31. But practically it will not
possible always to plan shells according to manual no. 31.
So that we will analyses the multiple cylindrical shell for
different parameters by using computer analysis program
SAP. By varying the parameters of the shell, behavior of
the shell is also varying. To know the behavior of the shell,
we will take two different dimensions of models whose
length to width ratio is 3. In those models two parameters
have been change; first one is radius and second is
thickness. After analysis we will compare the behavior of
the shells for different dimensions models.
2. METHODS OF ANALYSIS
A thin elastic shell resists the external load by developing
direct forces and bending moments. For a given geometry of
shell under some appropriate loading and support
conditions, it is possible that they can be safety neglected. In
such a case, the shell will resist the external forces through
direct or membrane forces. The shell is then said to be under
a membrane state of stress. The membrane theory is much
simpler as compared to the bending theory, since in this
theory, the membrane forces can be directly determined
from equilibrium. Because of its simplicity, the membrane
theory is often used as a reasonable basis for design. The
membrane analysis would give forces along the longitudinal
edges, which cannot be normally attained in practice by
providing a suitable support. Any corrective force or
displacement applied along these edges, so as to satisfy the
actual support condition, would lead to bending of the shell.
Hence, most of the cylindrical shell roof structures have to
be analysed considering bending, to get a more realistic
picture of force distribution in the shell.

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3. DETAILS OF MODELS
For analysis, following dimensions are considered which is
tabulated in tables. Properties and dimensions of multiple
cylindrical shells which are same for all models are shown
in table 1.
Table 1: Structural Properties and Dimensions of all Models
Live load 0.60 KN/m2
Grade of Concrete M-25
Type of Steel HYSD bars
Column Height 5.0 m
Column Size 1.0 m X 0.5 m
Column Support
condition
Fixed
Beam Size 1.8 m x 0.3m
Number of bay 3 bay
Different parameters of multiple cylindrical shell models of
type A, type A’, type B and type B’ are tabulated in table 2,
table 3, table 4 and table 5 respectively.
Table 2: Parameters of Type A models
TYPE A
Mod
el
Span in
X
directio
n
Span in
Y
directio
n
Angle
ɸ in
degre
e
Radiu
s
Thickn
ess
A1 30 10 30 10 0.075
A2 30 10 35 8.71 0.075
A3 30 10 40 7.77 0.075
A4 30 10 45 7.07 0.075
Table 3: Parameters of Type A’ models
TYPE A’
Mod
el
Span in
X
directio
n
Span in
Y
directio
n
Angle
ɸ in
degree
Radiu
s
Thickn
ess
A11 40 13.33 30 13.33 0.075
A22 40 13.33 35 11.62 0.075
A33 40 13.33 40 10.37 0.075
A44 40 13.33 45 9.425 0.075
Table 4: Parameters of Type B models
TYPE B
Mod
el
Span in
X
directio
n
Span in
Y
directio
n
Angle
ɸ in
degree
Radiu
s
Thickn
ess
B1 30 10 35 8.71 0.070
B2 30 10 35 8.71 0.075
B3 30 10 35 8.71 0.080
B4 30 10 35 8.71 0.100
Table 5: Parameters of Type B’ models
TYPE B’
Mode
l
Span in
X
directio
n
Span in
Y
directio
n
Angle
ɸ in
degre
e
Radiu
s
Thicknes
s
B11 40 13.33 35 11.62 0.070
B22 40 13.33 35 11.62 0.075
B33 40 13.33 35 11.62 0.080
B44 40 13.33 35 11.62 0.100
From table 2 and table 3, type A and type A’ models have
same thickness with different radius of different lengths.
And similarly from table 4 and table 5, type B and type B’
models have same radius with different thicknesses of
different lengths.
4. ANALYSIS RESULT
The main objective of this study is comparing the
parametric analysis of multiple cylindrical shell structure
with different lengths using analysis software SAP 2000.
The linear static analysis is used because we consider only
dead and live load on a multiple cylindrical shell. Stresses,
Moment developed per unit lengths and Forces acting per
unit length on the surface of shells are obtained from
analysis by varying thickness and radius for different
lengths.
For comparison of multiple cylindrical shells, we will
separate models in two different conditions.
1. Taking models having same thickness with
different radius and
2. Taking models having same radius with different
thickness for maximum moment, maximum forces and
maximum stresses which are presented below.
4.1 Maximum Element Moments
Figure 1 shows moment variation diagram and blue color
indicates the portion of maximum moment on the surface of
shell.
Fig 1: Moment variation diagram
4.1.1 Take Models Having Same Thickness with
Different Radius
4.1.1.1 Type A and Type A’ Models
Maximum moment value for type A and type A’ are
tabulated in table 6 and shown in figure 2.

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Table 6: Max. Moment value for Type A and Type A’
SAME THICKNESS WITH DIFFERENT RADIUS
MODEL
MAX.
MOMENT
IN KNm/m
MODEL
MAX.
MOMENT
IN KNm/m
A1 8 A11 12
A2 7.5 A22 14.3
A3 7 A33 16.5
A4 8.8 A44 12
6.5
8.5
10.5
12.5
14.5
16.5
30 35 40 45
Max.MomentsinKNm/m
Semi Central Angle
Max. Moments of Type A & TypeA' Models
Model A
Model A'
Fig 2: Comparison of Max. Moments for Type A Models &
Type A’ Models
4.1.2 Take Models Having Same Radius with
Different Thickness
4.1.2.1 Type B and Type B’ Models
Maximum moment value for type B and type B’ are
tabulated in table 7 and shown in figure 3
Table 7: Max. Moment value for Type B and Type B’
SAME RADIUS WITH DIFFERENT THICKNESS
MODEL
MAX.
MOMENT
IN KNm/m
MODEL
MAX.
MOMENT
IN KNm/m
B1 6.5 B11 12.1
B2 7.5 B22 14.3
B3 8.5 B33 13
B4 13.5 B44 24
6.5
10.5
14.5
18.5
22.5
26.5
70 80 90 100
Max.MomentsinKNm/m
Thickness of shell in milimeter
Max. Moments of Type B & Type B' Models
Model B
Model B'
Fig 3: Comparison of Max. Moments for Type B Models &
Type B’ Models
4.2 Maximum Element Forces
Figure 4 shows force variation diagram and blue color
indicates the portion of maximum forces on the surface of
shell.
Fig 4: Force variation diagram
Different Radius
Maximum force value for type A and type A’ are tabulated
in table 8 and shown in figure 5.
Table 8: Max. Forces value for Type A and Type A’
SAME THICKNESS WITH DIFFERENT
RADIUS
MODEL
MAX.
FORCE
IN KN/m
MODEL
MAX.
FORCE
IN KN/m
A1 187 A11 350
A2 176 A22 350
A3 176 A33 300
A4 165 A44 234

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160
200
240
280
320
360
30 35 40 45
Max.ForcesinKNm/m
Semi Central Angle
Max. Forces of Type A & Type A' Models
Model A
Model A'
Fig 5: Comparison of Max. Forces for Type A Models &
Type A’ Models
Different Thickness
Maximum force value for type B and type B’ are tabulated
in table 9 and shown in figure 6.
Table 9: Max. Forces value for Type B and Type B’
MODEL
MAX.
FORCE IN
KN/m
MODEL
MAX.
FORCE IN
KN/m
B1 176 B11 300
B2 176 B22 350
B3 198 B33 350
B4 275 B44 550
160
210
260
310
360
410
460
510
560
70 75 80 85 90 95 100
Max.ForcesinKNm/m
Max. Forces of Type B& Type B' Models
Model B
Model B'
Fig 6: Comparison of Max. Forces for Type B Models &
Type B’ Models
4.3 Maximum Element Stresses
Figure 7 shows stress variation diagram and blue color
indicates the portion of maximum stresses on the surface of
shell.
Fig 7: Stress variation diagram
Different Radius
Maximum stresses value for type A and type A’ are
Table 10: Max. Stresses value for Type A and Type A’
SAME THICKNESS WITH DIFFERENT
RADIUS
MODEL
MAX.
STRESSES
IN KN/m2
MODEL
MAX.
STRESSES
IN KN/m2
A1 13120 A11 18120
A2 14320 A22 19842
A3 11023 A33 17385
A4 11080 A44 22120
10000
12000
14000
16000
18000
20000
22000
30 35 40 45
Max.StressesinKNm/m
Semi Central Angle
Max. Stresses of Type A & Type A' Models
Model A
Model A'
Fig 8: Comparison of Max. Stresses for Type A Models &
Type A’ Models

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Different Thickness
Maximum stresses value for type B and type B’ are
Table 11: Max. Stresses value for Type B and Type B’
MODEL
MAX.
STRESSES
IN KN/m2
MODEL
MAX.
STRESSES
IN KN/m2
B1 12120 B11 17052
B2 14320 B22 19850
B3 12200 B33 18115
B4 14312 B44 20913
11000
13000
15000
17000
19000
21000
70 75 80 85 90 95 100
Max.StressesinKNm/m
Max. Stresses of Type B& TypeB' Models
Model B
Model B'
Fig 9: Comparison of Max. Stresses for Type B Models &
Type B’ Models
5. DISCUSSION
5.1 For Maximum Forces
1. From Figure 5, it is observed that if a type of models
having same thickness and different radius, then the
maximum forces value decreases with increased in semi
central angle for Type A and Type A’ models.
2. From figure 6, it is observed that if a type of models
having same radius and different thickness, then the
maximum forces value increases with increase in thickness
for Type B and Type B’ models. But certain reduction is
occurred at 80mm thickness due to change in dimensions of
shell in Type B’ models.
5.2 For Maximum Stresses
maximum stresses value decreases with increase in semi
central angle for Type A and Type A’ models up to 40
degree and then again increased.
maximum Stresses value increases with increase in
thickness for Type B and Type B’ models. But certain
reduction is occurred at 80mm thickness due to change in
dimensions of shell in both Type B and Type B’ models.
5.3 For Maximum Moments
maximum moment’s value decreases with increase in semi
central angle for Type A up to 40 degree and then again
increased. For Type A’ Models, maximum moments value
increases with increasing semi central angle up to 40 degree
and then again decrease.
maximum moment value increases with increase in
thickness for Type B and Type B’ models. But certain
reduction is occurred at 80mm thickness due to change in
dimensions of shell in Type B’ models.
3. The surface of maximum moment formed at the middle
end of the end shell but due to increase in length and width
of shell, the portion of maximum moments for some
models formed at that surface where two shells are joining
with each other at end. Which means direct forces exerted
by the end of the shell at its supports was not distributed
properly. To overcome this problem, we provided stiffener
beam along the curve edge of a shell. So analysis of
multiple cylindrical shell structure with stiffener beam is
carried out.
5.4. Analysis of Multiple Cylindrical Shells with
Stiffener Beam
The supports provided on edge of a shell along the curve
are called as Stiffener. Comparison of analysis of multiple
cylindrical shell structure with and without stiffener beam
is shown in figure 10 to figure 12.
188
325
212
393
182
317
213
391
0
50
100
150
200
250
300
350
400
450
TYPE A TYPE A' TYPE B TYPE B'
Max.ForcesinKN/m
Types of Models
Without
Stiffener
With
Stiffener
Fig 10 Variation of forces due to stiffener beam

_______________________________________________________________________________________
7.8
12.2
10.3
14.6
3.6
5.7
5.1
8
0
2
4
6
8
10
12
14
16
Max.MomentsinKNm/m
Types of Models
Without
Stiffener
With
Stiffener
Fig 11 Variation of moments due to stiffener beam
12620
18636
12680
19600
7625
12500
8125
13500
0
5000
10000
15000
20000
25000
Max.StressesinKN/m2/m
Types of Models
Without
Stiffener
With
Stiffener
Fig 12: Variation of stresses due to stiffener beam
6. CONCLUSION
From the analysis of multiple cylindrical reinforced
concrete shell structure with varying parameters following
conclusions can be drawn.
1. The behavior of reinforced concrete multiple cylindrical
shell structure whose length to width ratio is three was
different for different dimensional models.
2. Moments and Stresses of cylindrical shell structure are
significant when the semi central angle is 40 degree and
thickness of shell is 80mm.
3. Stiffener beams transferred the tension and moment
created by the shear from the shell on to the support.
4. Hence stiffener beams is an essential part of a multiple
cylindrical reinforced concrete shell structure.
REFERENCES
[1] Chandrasekaran S., Ashutosh Srivastava, Parijat
Naha. 2005. “Computational tools for shell
structures” Proc. of Intl. conf. on structures and road
transport (START-2005), IIT-Kharagpur, India, pp.
167-175.
[2] Ramaswamy G.S. 1968. “Design and construction of
concrete shell roof” First Edition, Mc-Graw Hill.
[3] Timoshenko, S.P., Woinowsky-Krieger, S. 1959.
“Theory of Plates and Shells” 2d ed., McGraw-Hill
Book Company, New York.
[4] Dr. Umesh Pendharkar, Ravindra Rai, 2012.
“Computer Aided Analysis of Multiple Cylindrical
Shell Structure Using Different Parameters”.
(IJERT) Vol. 1 Issue 3, May - 2012 ISSN: 2278-
0181
[5] Srinivasan Chandrasekaran1*, S.K.Gupta2, Federico
Carannante3,2009. “Design aids for fixed support
reinforced concrete cylindrical shells under
uniformly distributed loads”. International Journal
of Engineering, Science and Technology Vol. 1, No.
1, 2009, pp. 148-171
[6] Varghese P.C.2014. “Design of Reinforced Concrete
Shells and Folded Plates” First Edition, PHI
Learning Private Limited, Delhi.
[7] IS-2210-1988, “Criteria for Design of Reinforced
Concrete Shell Structures and Folded Plates”, B.I.S.,
New Delhi.
[8] Bandyopadhyay J.N.,1998. “Thin Shell Structures
Classical and Modern Analysis”, New Age
International Publishers, New Delhi.
[9] Chandrashekara K.,1986. “Analysis of Thin
Concrete Shells”, Tata McGraw Hill, New Delhi.
[10] “Design of Cylindrical Concrete Shell Roof”,
Manual No. 31, ASCE, New York, 1952

Analysis of cylindrical shell structure with varying parameters

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