Torsional Irregularity of Multi-Storey Structures Presentation
Torsional Irregularity of Multi-Storey Structures Presentation
Torsional Irregularity of Multi-Storey Structures Presentation
irregularity of
multi-storey
structures
PRESENTED BY:
Guided By:
Ms.Shinu Shajee
RAHILA THASKEEN
ROLL NO:07
S4 STRUCTURAL
ENGINEERING
INDEX
Introduction
Reviews
Methods of seismic analysis
Validation
Objective
Methodology
Analysis using ETABS
INTRODUCTION
Earthquake
Devastating and unpredictable.
Torsional behaviour during an earthquake.
Buildings are like inverted swings.
walls and columns are like the ropes
and the floor is like the cradle
Vibrate
back
and
forth
earthquakes.
during
contd..
If the mass on the floor of a
building is more on one side,
then that side of the building
moves more under ground
movement.
This building moves such that
its floors displace horizontally
as well as rotate.
6
contd..
uniformly placed vertical members
If the twist cannot be avoided, special
calculations need to be done to account
for this additional shear forces in the
design of buildings.
the Indian seismic code (IS 1893, 2002)
has provisions for such calculations. But,
for sure, buildings with twist will perform
poorly during strong earthquake shaking.
Torsion
contd..
Torsion
effect
in
symmetric
structures
Regular structures have uniformity
in height, cross-sectional area and
mass per storey and
yield a
general similarity in mode shape
of vibration.
Indian seismic codes have
torsional provisions for increase in
shear forces on lateral force
9
contd..
due to eccentricity between centre
of mass and centre of rigidity. This
is based on the static eccentricity
and floor plan dimensions which is
effective for irregular structures.
Account
for
accidental
eccentricity.
10
contd..
Torsional effect on asymmetric structures
Irregular structures can have irregular
configurations both in plan and elevation.
The lateral resistance of such structures is
usually torsionally unbalanced creating
large displacement amplifications and high
force concentrations within the resisting
elements which can cause severe damages
11
contd...
and at times leads to collapse of the
structure.
o Eccentric arrangement of the nonstructural element , asymmetric yielding,
presence of rotational component in
ground motions and the variations in the
input energy imparted by the ground
motions also contribute significantly to
the torsional response of buildings.
12
contd..
CR- centre
of rigidity
CMcentre of
mass
13
Eccentricity
o Accidental
eccentricity
Torsion irregularity
max drift/ avg drift <or = 1.2
Drift obtained from edge deflections
14
Contd..
15
REVIEWS
16
REVIEW ON PLAN
ASYMMETRIC
STRUCTURES
17
Review 1
Vipin
Gupta
and
Dr.P.S
Pajgade
investigated torsional behaviour of
multi-storey structures as well as
vertical irregularities. They reached into
a conclusion that torsion is an important
factor leading to collapse of building
during earthquake. As a result the
building needed to be designed for
design and accidental eccentricity.
18
Review 2
Rajalaxmi K.R et al., carried out an
analysis of 30 storeyed regular rc frame in
SAP 2000.Non-linear static analysis has
done.
Mass irregularity, Stiffness irregularity and
setbacks were considered.
Mass irregular-More hinges formed
Stiffness irregular The building displaced
19
20
Review 3
C. Justine J et al,. begun their
work by quantifying the similarities
and differences in equivalent static
method and response spectrum
method of tall regular buildings
analysis under frequency period
and torsional period based on IS
code provisions.
Design moments of columns and
roof displacements are taken 21
as
contd..
The buildings considered were 3D reinforced
column beam structures with rigid diaphragms
having 'm x m' bays.9 storey building with
different floor areas were investigated
They compared the variation in equivalent
static method and response spectrum method
wherein
they
found
that
RSM
was
overestimated.
They also studied on the effects of torsional
modes in low raise buildings
22
Review 4
Sachin G. M et al,. studied on the
influence of the torsion effects on
the behaviour of structure is done.
In building , two cases are
considered
that
is
without
considering torsion and considering
torsion.
Results are compared in terms of
percentage Ast in columns.
23
Review 5
M.R Wakchaure et al,. studied the
influence of torsion effects on the behaviour
of structure. The indian standard code of
practice IS 1893(part1:2002) guidelines and
methodology were used for analysis.
The structural analysis and design of nine
storey RC asymmetrical frame building was
done with the help of staad.pro software.
25
Review 6
Bolander et al,.have evaluated the
effects of torsion on the nonlinear
seismic response of a thirteen-story
reinforced concrete frame-wall structure
with an asymmetric stiffness in plan.
They conducted their investigation on
existing building structure,located in
Berkeley,was modeled in ETABS to
perform several analyses.
27
Review 7
Nischith S et al,. studied four
types of structures with varying
eccentricity subjected to Pushover
Analysis and Non-Linear THA.
One symmetrical structure with
zero
eccentricity
and
three
asymmetrical
structures
with
varying eccentricity.
The performance of the structures
29
contd..
The analysis of the structural models is done
in ETABS.
The results have shown that the structures
with less eccentricity and in the direction of
the columns orientation are performing well,
also ductility, drift, and lateral displacement
depends on the eccentricity of the structures
and greater displacement is seen the
structure with highest eccentricity.
30
REVIEW ON TORSION
ANALYSIS OF
STRUCTURES WITH
SHEAR WALL
31
Review 8
Amin Alavi et al,.made an attempt to
realise the seismic response of the
structures, for various location of shear
walls on RC building having re-entrant
corners on high seismic zones.
The studied a five storey building with six
different shear wall locations They
considered the accidental torsion of both
negative and positive X and Y directions.
32
33
Review 9
Gunay ozmen et al; explained the
conditions
which
cause
torsional
irregularity coefficient to exceed the upper
bound value of 2 as per the code.
A series of eight walled and framed
sample structures with different structural
wall configurations was chosen and their
behaviour under earthquake loading were
considered.
34
Here
found
that
torsional
irregularity coefficient is maximum
when the number of axes and
number of stories are low. Also
when structural walls are placed as
close as posible to the gravity
centres without coinciding them ,
the
coefficient
were
found
maximum.
35
Review 10
Bhojaraj M et al,. in their study, Response
Spectrum method is used to analyze the
irregular shaped RCC structure.
The investigation is carried to know the
contribution of different shapes and location of
shear walls to lateral strength and lateral
stiffness of the high rise irregular building.
The comparison has been carried out between
building with L SHAPE SW, C SHAPE SW and
LINE SHAPE SW.
36
They
concluded
that
the
eccentricities between centre of
mass and centre of resistance are
more significant to the torsion
behaviour of structures during an
earthquake.
It was found that the shear wall
location, shape, size and total
number of shear wall in a building
37
acts as an important factor for the
VARIOUS METHODS OF
TORSION ANALYSIS
38
Review 11
Anil K.Chopra et al; investigated on
the accuracy of response spectrum
analysis for estimating the maximum
response of the building directly from
earthquake
design
spectrum
and
evaluated it with the objective of
developing better analysis procedures
comparing building codes.
The paper demonstrated that for a fixed
fundamental period of building, the
response contribution of higher vibration
39
40
Review 12
Karoley A Zalka; Regarding torsion his
book presented a closed-form solutions for
the maximum deflection and rotation of
the building.
The investigations spectacularly show the
contribution of the two key (bending and
shear) stiffnesses as well as the interaction
between them. It deals with the frequency
analysis of buildings..
41
Comments on literature
Helped for a better understanding of response
spectrum analysis and equivalent static analysis
of multi-storey structures and its torsional effects.
oThe seismic responses caused by the asymmetric
structures were the main area of interest.
oLess comparisons are found regarding the plan
asymmetric structures. There is less information
regarding usage of cores so as to increase the
stiffness and reduce torsion.
o
43
Contd..
oThe
information
regarding
the
introduction of shear walls, infills etc..
which in turn increases the stiffness of
the structure and the overall stability of
the structures were investigated by many
researchers
but
strengthening
to
torsionally irregular structure was not the
prime motive of many.
oThere is no much information on the
torsion effect for height of the high rise
buildings.
44
METHODS OF ANALYSIS
Linear static analysis
Linear dynamic analysis
Response spectrum analysis
Elastic time history analysis
Non-linear static analysis
Non-linear dynamic analysis
45
COMPUTATIONAL TOOL
ETABS 2015
ETABS is an ultimate integrated
software
package
for
the
structural analysis and design of
buildings.
Incorporating
40
years
of
continuous
research
and
development, this latest ETABS
offers unmatched 3D object based
modelling and visualization tools,
46
CONTD..
47
METHODS OF SEISMIC
ANALYSIS
Equivalent Static Load Method:
o Series of forces acting on structure are
defined to represent earthquake ground
motion
o Building respond in its fundamental mode
o Basic response spectrum defined by
choosing appropriate values of basic
seismic acceleration, soil profile type and
response reduction factors.
49
Contd..
o They yields approximate values of
base shear and the total permanent
load is determined.
o They specifies how the load is
distributed along the height of the
structure.
50
51
VALIDATION
Validation done using ETABS 2015
One bay 9 storied building has
been analyzed using ESM and
RSM.
Material properties
M20 grade of concrete and Fe
415
Storey data
Number of stories = 9
Contd..
Storey height =3.0 meters
Bay width along X-direction = 5.0 m
Bay width along Y-direction = 5.0 m
Analysis methodology
Seismic analysis is carried out for the
building using static approach -ESM and
dynamic approach - RSM as proposed in IS
1893 (part 1) : 2002 with .
53
Contd..
Importance factor I=1
Response reduction factor R= 5,
and Zone factor = 0.36.
The buildings are considered to be founded
on medium soil (type 2). Etabs 2015 is used
as the computational tool. For validation
storey displacements and roof displacements
are taken as parameters of study.
54
Deformed
55
56
roof displacements
RSM
80
60
40
20
10
57
Roof displacement
symmetric buildings
Type of
of
one
bay
building
RSM
RSM
ESM
ESM
U1
U2
U1
U2
U1
U2
U1
U2
1.86
1.81
0.08
1.91
1.89
0.09
7.56
8.4
0.36
8.70
8.87
0.43
15.21
17.14
0.71
16.29
17.01
0.82
25.06
30.32
1.21
27.76
31.98
1.34
35.87
40.84
1.69
36.56
40.9
1.75
47.41
59.19
2.14
49.05
60.04
2.38
58
OBJECTIVE
Analyze the seismic performance of the
structure.
To analyze structure along the height of
the building
Study of torsional irregularity of
symmetric and asymmetric plan structures
To strengthen the most torsionally
irregular structure.
59
METHODOLOGY
Building
configurations
are
introduced
Symmetric structure- rectangular in
plan
Asymmetric
structure
rectangular,L-shape and C shape
Analysis done using etabs.
The material properties and zonal
60
consideration informations collected
Contd..
The sections are introduced and also the load
patterns.
Linear analysis completed
Design check has been made and platform for
modal analysis has made ready.
Set of response parameters of torsion is used to
illustrate the effect of torsion in these structures.
Torsion parameters are outlined and are
discussed.
61
CONTD
Run analysis for linear analysis
Response function and response
spectrum load cases defined
Response spectrum modal amplitude for
any direction defined in load combinations
Modal response spectrum analysis carried
out to obtain the torsional irregularity of
the structure.
63
COMPARISON OF A STRUCTURE
ALONG HEIGHT
Two structures are compared along its height.
A symmetrical structure and an L shaped
asymmetrical structure
The structures compared are G+12 and G+17
structures.
Zonal Considerations
64
65
66
67
68
69
symmetric
70
X direction
Sto
rey
12
11
10
9
8
7
6
5
4
3
2
Edi
1
C
m
10
10
10
10
10
10
10
10
10
10
10
=
10
eccentricity
Y direction
Cm Cr Esi bi edi
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
10 10 0 20 1
esi=
10 10static
0 20 1
71
Storey
13
13
12
12
11
11
10
10
Storey
6
5
6
5
0
0.8
1.2
1.4
1.6
1.8
design eccentricity
0
0.8
1.2
1.4
1.6
1.8
design eccentricity
72
Store
y
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Cm
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Cr
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Esi
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
bi
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
edi
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
X
Y
Store
y
Cm
Cr
Esi
bi
edi
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
73
Storey
18
18
16
16
14
14
12
12
10
10
Storey
0
0.8
1.2
1.4
1.6
1.8
design eccentricity
0
0.8
1.2
1.4
1.6
1.8
design eccentricity
74
L shape
75
Cm
Cr
Esi
bi
edi
12
8.5711
8.2406
-0.3305
20
0.50425
11
8.585
8.2818
-0.3032
20
0.5452
10
8.5892
8.3199
-0.2693
20
0.59605
8.5912
8.3556
-0.2356
20
0.6466
8.5924
8.3889
-0.2035
20
0.69475
8.5932
8.4198
-0.1734
20
0.7399
8.5938
8.4485
-0.1453
20
0.78205
8.5942
8.4752
-0.119
20
0.8215
8.5945
8.5005
-0.094
20
0.859
8.5948
8.5256
-0.0692
20
0.8962
8.595
8.5543
-0.0407
20
0.93895
8.5951
8.598
0.0029
20
1.00435
76
Cm
Cr
Esi
bi
edi
12
11
10
9
8
7
6
5
4
3
2
1
8.7942
8.7979
8.799
8.7995
8.7998
8.8
8.8002
8.8003
8.8004
8.8004
8.8005
8.5863
8.6007
8.6142
8.6268
8.6387
8.65
8.6607
8.671
8.6811
8.6917
8.7044
-0.2079
-0.1972
-0.1848
-0.1727
-0.1611
-0.15
-0.1395
-0.1293
-0.1193
-0.1087
-0.0961
20
20
20
20
20
20
20
20
20
20
20
0.68815
0.7042
0.7228
0.74095
0.75835
0.775
0.79075
0.80605
0.82105
0.83695
0.85585
8.8005
8.7252
-0.0753
20
0.88705
77
G+12
eccentricity along X direction
Storey
14
14
12
12
10
10
Storey
0
0.4
0.5
0.6
0.7
0.8
0.9
1.1
design eccentricity
0
0.65
0.7
0.75
0.8
0.85
0.9
design eccentricity
78
X direction
Storey
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Cm
8.5711
8.585
8.5892
8.5912
8.5924
8.5932
8.5938
8.5942
8.5945
8.5948
8.595
8.5951
8.5953
8.5954
8.5955
8.5956
8.5957
Cr
8.0846
8.1272
8.1675
8.2058
8.2425
8.2774
8.3108
8.3426
8.3728
8.4015
8.4287
8.4545
8.479
8.5026
8.5267
8.5547
8.5981
Esi
-0.4865
-0.4578
-0.4217
-0.3854
-0.3499
-0.3158
-0.283
-0.2516
-0.2217
-0.1933
-0.1663
-0.1406
-0.1163
-0.0928
-0.0688
-0.0409
0.0024
bi
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
edi
0.27025
0.3133
0.36745
0.4219
0.47515
0.5263
0.5755
0.6226
0.66745
0.71005
0.75055
0.7891
0.82555
0.8608
0.8968
0.93865
1.0036
79
Y direction
Storey
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Cm
8.7942
8.7979
8.799
8.7995
8.7998
8.8
8.8002
8.8003
8.8004
8.8004
8.8005
8.8005
8.8006
8.8006
8.8006
8.8007
8.8007
Cr
8.5287
8.5434
8.5576
8.5712
8.5842
8.5967
8.6087
8.6202
8.6312
8.6419
8.6522
8.6622
8.6719
8.6817
8.692
8.7045
8.7253
Esi
-0.2655
-0.2545
-0.2414
-0.2283
-0.2156
-0.2033
-0.1915
-0.1801
-0.1692
-0.1585
-0.1483
-0.1383
-0.1287
-0.1189
-0.1086
-0.0962
-0.0754
bi
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
edi
0.60175
0.61825
0.6379
0.65755
0.6766
0.69505
0.71275
0.72985
0.7462
0.76225
0.77755
0.79255
0.80695
0.82165
0.8371
0.8557
80
0.8869
G+17
eccentricity along X direction
Storey
18
18
16
16
14
14
12
12
Storey
10
10
0
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
design eccentricity
1.1
0
0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95
design eccentricity
81
84
ELEVATION
85
MODEL -II
Asymmetric building -model II
oRectangular in shape
o4 bays in X direction and 3 bays
in Y-direction.
oSpacing 3.5m in X direction and
4.5m Y-direction.
86
PLAN
87
ELEVATION
88
MODEL-III
Asymmetric building model III- L
shaped building
o4 bays in X direction and 3 bays
in Y-direction.
oSpacing 3.5m in X direction and
4.5m Y-direction.
89
PLAN
90
ELEVATION
91
MODEL-IV
Asymmetric building model IV- C
shaped building
o4 bays in X direction and 3 bays
in Y-direction.
oSpacing 3.5m in X direction and
4.5m Y-direction.
92
PLAN
93
ELEVATION
94
95
Contd
Zonal Considerations
Zone : IV
Soil Type : II
Importance factor : 1
Reduction Factor : 5
Zone Factor : 0.24
Live Load : 3kN/m2
96
Contd
Linear static analysis
o Basic dimensioning and defining
material properties
oDefining beam and column
dimensions and drawing them.
oDefining load cases and
combinations
97
98
99
To find torsional
irregularity
1) Obtain the scaling for each mode as the
response-spectrum modal amplitudefrom
the Response Spectrum Modal Information.
2) Select the load Combinations and add new
combinations. Select modal in drop down list
under load name and enter mode number
and scale factor for the specific mode from
response spectrum modal information as
new combinations and rerun the analysis.
100
Contd..
3) Compute the average story drift
at two ends of the building, then
compare with the maximum story
drift
for
that
specific
mode
i.e.Dmax/Davg<1.2 for each mode
and
thus
find
the
torsional
irregularity.
101
Analysis results
102
MODEL I
103
M
O
D
E
S
H
A
P
E
S
Case
Mode
Period
Circular
Frequency Frequency
sec
cyc/sec
rad/sec
Modal
1.519
0.659
4.1376
Modal
1.008
0.992
6.2327
Modal
0.991
1.009
6.3407
Modal
0.494
2.025
12.7212
Modal
0.324
3.089
19.408
Modal
0.313
3.197
20.0849
Modal
0.287
3.482
21.8807
Modal
0.201
4.975
31.2581
Modal
0.183
5.462
34.3219
Modal
10
0.171
5.835
36.6603
Modal
11
0.155
6.462
40.6
Modal
12
0.128
7.806
49.0438
104
MODES 1, 2,3
X direction
Twisting
Y direction
105
ECCENTRICITY
X DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi
+0.05bi
14
0.7
14
0.7
14
0.7
14
0.7
14
0.7
14
0.7
14
0.7
106
ECCENTRICITYY DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.
5esi+0
.05bi
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
6.75
6.75
13.5
0.675
107
Torsion irregularity
The torsional irregularity can be interpreted as
the ratio of maximum drift to the average drift
of the individual story.
108
Torsional irregularity
Storey
7
6
5
4
3
2
1
GF
max
avg
0.000288 0.000288
0.000529 0.000529
0.000763 0.000763
0.000973 0.000973
0.001146
0.001146
0.001278 0.001278
0.0001376 0.0001376
0.000731 0.000731
max /avg
1
1
1
1
1
1
1
1
109
MODE
L II
110
M
O
D
E
S
H
A
P
E
S
Case
Mode
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
1
2
3
4
5
6
7
8
9
10
11
12
Period
sec
1.079
0.851
0.601
0.295
0.251
0.173
0.157
0.118
0.109
0.085
0.079
0.078
Circular
Frequenc Frequenc
y
y
cyc/sec
rad/sec
0.927
5.8255
1.175
7.3854
1.665
10.4622
3.388
21.2881
3.989
25.0649
5.776
36.2914
6.383
40.1068
8.484
53.3068
9.155
57.5247
11.705
73.5423
12.606
79.2086
12.822
80.5655
111
MODES 1, 2,3
X direction
Y direction
torsion
112
ECCENTRICITY
X DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi+
0.05bi
7.4345
8.9012
1.4667
14
2.90005
7.2201
9.3658
2.1457
14
3.91855
7.1524
9.7459
2.5935
14
4.59025
7.1192
10.1122
2.993
14
5.1895
7.0995
10.5064
3.4069
14
5.81035
7.0864
10.9414
3.855
14
6.4825
7.0771
11.3646
4.2875
14
7.13125
113
ECCENTRICITYY DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi
+0.05bi
6.5098
5.6962
-0.8136
13.5
-0.5454
6.7292
5.4129
-1.3163
13.5
-1.29945
6.7985
5.1395
-1.659
13.5
-1.8135
6.8325
4.8813
-1.9512
13.5
-2.2518
6.8527
4.6309
-2.2218
13.5
-2.6577
6.8661
4.4019
-2.4642
13.5
-3.0213
6.8756
4.2512
-2.6244
13.5
-3.2616
114
Torsional irregularity
Storey
max
avg
0.000209
0.0002035
1.027
0.000315
0.0002715
1.160
0.000427
0.0003385
1.261
0.000514
0.0003885
1.323
0.000580
0.0004195
1.382
0.000613
0.0004200
1.4595
0.000588
0.0003720
1.580
0.000284
0.0001715
1.655
2
1
GF
max /avg
115
MODEL
III
116
M
O
D
E
S
H
A
P
E
S
Case
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Mode
Period
Frequency
Circular
Frequency
1
2
3
4
5
6
7
8
9
10
11
12
sec
1.037
0.843
0.561
0.278
0.247
0.162
0.147
0.113
0.104
0.083
0.076
0.075
cyc/sec
0.964
1.186
1.783
3.6
4.051
6.175
6.794
8.853
9.599
12.058
13.132
13.398
rad/sec
6.0594
7.4529
11.2051
22.6169
25.4546
38.7986
42.6864
55.6253
60.3133
75.7614
82.5131
84.1839
117
MODES 1, 2,3
X direction
Y direction
torsion
118
ECCENTRICITY
X DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi+
0.05bi
6.8789
8.4973
1.6184
14
3.1276
6.6109
9.0271
2.4162
14
4.3243
6.526
9.4703
2.9443
14
5.11645
6.4843
9.8944
3.4101
14
5.81515
6.4595
10.3427
3.8832
14
6.5248
6.4431
10.8277
4.3846
14
7.2769
6.4314
11.2944
4.863
14
7.9945
119
ECCENTRICITYY DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi
+0.05bi
5.6936
5.1672
-0.5264
13.5
-0.1146
5.9192
4.9613
-0.9579
13.5
-0.76185
5.9906
4.7561
-1.2345
13.5
-1.17675
6.0257
4.56
-1.4657
13.5
-1.52355
6.0466
4.3723
-1.6743
13.5
-1.83645
6.0604
4.2084
-1.852
13.5
-2.103
6.0702
4.1192
-1.951
13.5
-2.2515
120
Torsional irregularity
Storey
max
avg
0.000226
0.0002125
1.063
0.000318
0.0002805
1.133
0.000428
0.000344
1.244
0.000518
0.000393
1.318
0.000583
0.000421
1.384
0.000616
0.000495
1.468
0.000592
0.000371
1.590
0.000286
0.000170
1.682
2
1
GF
max /avg
121
MODEL
IV
122
M
O
D
E
S
H
A
P
E
S
Case
Mode
Period
Circular
Frequency Frequency
sec
cyc/sec
rad/sec
Modal
1.021
0.979
6.1524
Modal
0.802
1.247
7.8375
Modal
0.575
1.74
10.9307
Modal
0.268
3.726
23.41
Modal
0.236
4.242
26.6515
Modal
0.163
6.152
38.6554
Modal
0.145
6.877
43.2101
Modal
0.107
9.303
58.4548
Modal
0.101
9.939
62.4502
Modal
10
0.082
12.187
76.5718
Modal
11
0.082
12.236
76.8817
Modal
12
0.075
13.406
84.2325
123
MODES 1, 2,3
X direction
Y direction
torsion
124
ECCENTRICITY
X DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi+
0.05bi
7.5672
9.1387
1.5715
14
3.05725
7.2867
9.601
2.3143
14
4.17145
7.1983
9.9783
2.78
14
4.87
7.155
10.3373
3.1823
14
5.47345
7.1293
10.7164
3.5871
14
6.08065
7.1123
11.1245
4.0122
14
6.7183
7.1002
11.5091
4.4089
14
7.31335
125
ECCENTRICITYY DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi
+0.05bi
7.8769
8.6946
0.8177
13.5
1.90155
7.5989
8.8372
1.2383
13.5
2.53245
7.5114
8.9735
1.4621
13.5
2.86815
7.4685
9.107
1.6385
13.5
3.13275
7.443
9.2395
1.7965
13.5
3.36975
7.4262
9.3568
1.9306
13.5
3.5709
7.4142
9.4114
1.9972
13.5
3.6708
126
Torsional irregularity
Storey
max
avg
7
6
5
4
3
2
1
GF
0.000394
0.000602
0.000811
0.000983
0.001107
0.001168
0.001111
0.000535
0.0003875
0.0005135
0.000634
0.000729
0.0007835
0.0007825
0.0006885
0.0003155
max /avg
1.016
1.172
1.279
1.34
1.412
1.492
1.613
1.695
116
MODEL V
Strengthening of model
128
129
M
O
D
E
S
H
A
P
E
S
Case
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Modal
Mode
Period
1
2
3
4
5
6
7
8
9
10
11
12
sec
0.59
0.425
0.332
0.122
0.1
0.082
0.081
0.077
0.072
0.072
0.052
0.047
Circular
Frequency Frequency
cyc/sec
1.696
2.356
3.008
8.177
10.034
12.19
12.276
12.988
13.851
13.859
19.18
21.284
rad/sec
10.6538
14.8005
18.9022
51.3764
63.0454
76.5911
77.1308
81.6066
87.0289
87.0812
120.5093
133.7316
130
MODES 1, 2,3
X direction
Y direction
torsion
131
ECCENTRICITY
X DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi+
0.05bi
7
6
5
4
3
2
1
7
6.5653
6.4411
6.3823
6.348
6.3255
6.3097
6.984
6.9696
6.9666
6.956
6.9328
6.8758
6.733
-0.016
0.4043
0.5255
0.5737
0.5848
0.5503
0.5833
14
14
14
14
14
14
14
0.676
1.30645
1.48825
1.56055
1.5772
1.52545
1.63495
132
ECCENTRICITYY DIRECTION
Storey
Cm
Cr
Esi
bi
edi=1.5esi
+0.05bi
10.6573
8.3201
-2.3372
14
-2.8058
10.7014
8.2601
-2.4413
14
-2.96195
10.762
8.2429
-2.5191
14
-3.07865
10.8393
8.2348
-2.6045
14
-3.20675
10.929
8.2301
-2.6989
14
-3.34835
11.0227
8.227
-2.7957
14
-3.49355
11.0959
8.2248
-2.8711
14
-3.60665
122
Torsional irregularity
Storey
max
avg
max /avg
0.000238
0.000232
1.025862
0.000248
0.000243
1.02268
0.000251
0.000245
1.026585
0.000243
0.000237
1.025316
0.000223
0.000217
1.02765
0.000187
0.000182
1.027473
0.000134
0.000131
1.02682
0.000065
6.35E-05
1.023622
134
COMPARISON OF RESULTS
135
MODE
NO:
MODEL
I
MODEL
II
MODEL
III
MODEL
IV
MODEL
V
0.59s
1.008
0.851
0.843
0.802
0.425
0.991
0.601
0.561
0.575
0.332
136
Modes
1.6
1.4
1.2
1
Period
0.8
0.6
0.4
0.2
0
10
12
14
16
18
20
22
24
26
28
30
Mode
model I
model II
model III
model IV
model V
137
32
139
eccentricity
140
Eccentricity X direction
Design eccentricity
9
8
7
6
5
4
3
2
1
0
Storey
MODEL I
MODEL II
MODEL III
MODEL IV
MODEL V
141
Design eccentricity
Eccentricity Y direction
4
3.5
3
2.5
2
1.5
1
0.5
0
Storey
MODEL I
MODEL II
MODEL III
MODEL IV
MODEL V
142
Torsional irregularity
145
TORSIONAL IRREGULARITY
Torsional irregularity
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
GF
STOREY
MODEL I
MODEL II
MODEL III
MODEL IV
MODELV
146
148
149
Drift
150
Drift X direction
0
0
0
0
0
0
0
00
Drift
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
Storey
Model I
Model II
Model III
Model IV
Model V
151
Drift Y direction.
0
0
0
Drift
0
0
0
0
0
Storey
Model I
Model II
Model III
Model IV
Model V
152
155
displacement
156
Displacement X direction
60
Displacement
50
40
30
20
10
0
Storey
model I
model II
model III
model IV
model V
157
Displacement in Y direction
45
40
Displacement
35
30
25
20
15
10
5
0
model I
model II
Storey
model III
model IV
model V
158
BASE SHEAR
160
X- DIRECTION
161
Y DIRECTION
162
163
164
CONCLUSION
The thesis mainly focussed on the
seismic response especially torsional
response of plan irregular structures. The
major conclusions drawn were:
From the analysed model the estimated
time period for first modes indicated
that the strengthened model have less
vulnerability to seismic action
The model IV had the maximum
tendency for seismic action which was
evident from eccentricity
165
167
168
REFERENCES
Anil K.Chopra; Ernesto F.Cruz(1986), " Elastic
earthquake response of building frames ". Journal of
structural engoneering Vol 112 NO:3.
R.D. Kangwai, S.D. Guest, S. Pellegrino(1998),"An
introduction
to
the
analysis
of
symmetric
structures". Computers and Structures 71 (1999)
671688.
Dhiman basu and sudhir.K. Jain(2004)."Seismic
analysis of asymmetric buildings with Flexible Floor
Diaphragms". Journal of structural engineering ASCE.
Gunay ozmen (2004),"Excessive torsional irregularity
in multi-storey".Digest 2004,.
C. Justine Jose, T.P. Somasundaran and V
Mustafa(2010),"Prediction of seismic torsional effect
in tall symmetric buildings". IJJRRAS.
170
171
172
173
THANK YOU
174