Earthquake Analysis of Reinforced Concrete Oblique Columns and Y Shaped Columns using ETABS A Comparative Study

International Journal of Trend in Scientific Research and Development (IJTSRD)
Volume 6 Issue 4, May-June 2022 Available Online: www.ijtsrd.com e-ISSN: 2456 – 6470
@ IJTSRD | Unique Paper ID – IJTSRD50099 | Volume – 6 | Issue – 4 | May-June 2022 Page 560
Earthquake Analysis of Reinforced Concrete Oblique Columns
and Y-Shaped Columns using ETABS: A Comparative Study
Prof. Dr. P. L. Naktode1
, Yogesh R. Pawar2
, Shubham V. Sarode2
,
Sujay S. Khairnar2
, Bhavesh S. Chaudhari2
, Vaibhav M. Bedse2
1
Professor, 2
B. Tech. Student,
1,2
Department of Civil Engineering, School of Engineering and Technology,
Sandip University, Nashik, Maharashtra, India
ABSTRACT
This dissertation work deals with the comparative study of behavior
of oblique columns with Y-shaped RC column for a high rise
structures. Now a day’s utility or floor area of Residential RC
Structure is very costly. Any analysis and design approach which
enhances the utility area of residential or commercial buildings is
highly appreciable. Many researchers/design engineers attempted to
achieve it. Strategies like floating columns, central core columns and
cantilever beam structures are one of the usual techniques. In the
present study, oblique columns and Y-shaped columns are adopted
instead of conventional (rectangular or square) columns, 6 storied
structures is considered for analysis and comparative study between
oblique columns and Y-shaped columns is to be adopted. All the
analysis and design work is conducted using ETABS 2013 version.
The project concluded that Maximum Storey Displacement in
oblique columns is 6.3 mm and in Y-shaped columns is 50.27 mm.
Results show that maximum storey displacement is increased in Y-
shaped Columns by 43.97 mm. It means maximum storey
displacement is increased in Y-shaped columns by 697.94%. Hence
oblique columns give better results in storey displacement. Maximum
Storey Drift in oblique columns is 0.000162 mm and in Y-shaped
columns is 0.000248 mm. The difference of maximum storey drift
between oblique columns and Y-shaped is 0.000086 mm. Maximum
Storey Drift in Y-shaped columns is increased by 53.08 % as that of
How to cite this paper: Prof. Dr. P. L.
Naktode | Yogesh R. Pawar | Shubham
V. Sarode | Sujay S. Khairnar | Bhavesh
S. Chaudhari | Vaibhav M. Bedse
"Earthquake Analysis of Reinforced
Concrete Oblique Columns and Y-
Shaped Columns using ETABS: A
Comparative Study"
Published in
International Journal
of Trend in
Scientific Research
and Development
(ijtsrd), ISSN: 2456-
6470, Volume-6 |
Issue-4, June 2022, pp.560-571, URL:
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oblique columns. The lower base shear is getting in oblique columns and the higher base shear is getting in Y-
shaped columns. Base shear in oblique column is 831.22 kN while 1096.68 in y-shaped column. It means that
base shear value is increased by 32.07% in Y-shaped column as compared to oblique columns. The joint of the
Y-shaped holds to be weak under seismic loading. Necessarily requires the strengthening the joins of Y-shaped
column. Maximum Storey Stiffness in oblique columns is 17 1757254.595 kN/m and 733562.715 in Y-shaped
columns. Results of maximum storey stiffness show that stiffness gets deceases in y-shaped columns as
compared to oblique columns. It is decreased by 58.25%. Oblique columns offer best resistance to lateral loads.
Hence, it needs optimum design procedure to proceed for further studies and also for construction. The oblique
columns and Y-shaped columns can be used for architectural purpose by giving the pleasing appearance to
inclined support members, which increases the aesthetic appearance of the structure.
KEYWORDS: Columns, Oblique Columns, Y-shaped Columns, Equivalent Static Method, Response Spectrum
Method, Displacement, Storey Drift, Stiffness, Base Shear, Time Period, etc
INTRODUCTION
A column or pillar in architecture and structural
engineering is a structural element that transmits,
through compression, the weight of the structure
above to other structural elements below. In other
words, a column is a compression member. The term
column applies especially to a large round support
(the shaft of the column) with a capital and a base or
pedestal, which is made of stone or appearing to be
so. A small wooden or metal support is typically
called a post, and supports with a rectangular or other
IJTSRD50099

International Journal of Trend in Scientific Research and Development @ www.ijtsrd.com eISSN: 2456-6470
non-round section are usually called piers. Simply, a
vertical member whose effective length is greater
than 3 times Its least lateral dimension carrying
compressive loads is called as a column. Columns
transfer the loads from the beams or slabs to the
footings or foundations. The inclined member
carrying compressive loads as In the case of frames
and trusses is called as struts. The pedestal is a
vertical compression member whose effective length
is less than 3 times it’s least lateral dimension.
For the purpose of wind or earthquake engineering,
columns may be designed to resist lateral forces.
Other compression members are often termed
"columns" because of the similar stress conditions.
Columns are frequently used to support beams or
arches on which the upper parts of walls or ceilings
rest. In architecture, "column" refers to such a
structural element that also has certain proportional
and decorative features. A column might also be a
decorative element not needed for structural purposes;
many columns are engaged, that is to say form part of
a wall. A long sequence of columns joined by an
entablature is known as a colonnade.
Fig. 1 Columns
A. Classification of Columns
There are several types of columns which are used in
different parts of structures. Column is a vertical
structural member that carries loads mainly in
compression. It might transfer loads from a ceiling,
floor slab, roof slab, or from a beam, to a floor or
foundations. Commonly, columns also carry bending
moments about one or both of the cross-section axes.
In this article, different types of columns used in
building construction will be discussed.
Columns are classified based on the several
conditions which include:
A. Based on Types of Reinforcement
B. Based on Types of Loading
C. Based on Slenderness Ratio
D. Based on Shape
E. Based on Construction Material
Fig. 2 Square and Rectangular Columns
METHODOLOGY
A. Problem Statement
Sophisticated construction industry is rapidly
increasing due to the developments and demands for
population. The new idea is that the columns are not
vertical. We can build multi-storied building
buildings with oblique columns. But the seismic
performance should be studied to know whether these
new construction techniques adaptable or not.
Because, the performance of the high-rise, mid-rise
and low-rise buildings will be different from each
other for different angles under seismic loading. So it
is very important to study the seismic performance for
different types of building and also compare with the
conventional method of construction. If it is
replaceable for the normal constructions and with
more advantages, it will be a revolutionary change in
civil engineering world.
B. Aim of the Study
The aim of design is the achievement of an acceptable
probability that structures being designed will
perform satisfactorily during their intended life. With
an appropriate degree of safety, they should sustain
all the loads and deformations of normal construction
and use and have adequate durability and adequate
resistance to the effects of seismic and wind.
Structure and structural elements shall normally be
designed by Limit State Method. Account should be
taken of accepted theories, experiment and experience
and the need to design for durability. Design,
including design for durability, construction and use
in service should be considered as a whole. The
realization of design objectives requires compliance
with clearly defined standards for materials,
production, workmanship and also maintenance and
use of structure in service. Analyzing the behavior of
oblique columns and Y-shaped columns is the main
aim of this study.
C. Objectives of the Study
The main purpose of analysis is to compare the
response of the oblique columns and Y-shaped

columns under seismic loading. Following are the
objectives of the present study:-
A. To analyse G+5 storied reinforced concrete (RC)
structure under seismic loading with oblique
columns.
B. To analyse G+5 storied reinforced concrete (RC)
structure under seismic loading with Y-shaped
columns.
C. Comparative analysis of oblique columns and Y-
shaped columns under seismic loading with
respect to displacement, base shear, storey drift,
stiffness and time period.
D. Methodology of the Work
The different phases of this project of work are shown
in the following diagram. The figure simply describes
the experimental strategy of this study step by step.
A. Review the existing literatures on oblique
columns and Y-shaped columns,
B. Analysis of G+5 storied reinforced concrete (RC)
structure under seismic loading with oblique
columns.
C. Analysis of G+5 storied reinforced concrete (RC)
structure under seismic loading with Y-shaped
columns.
D. Comparative study of oblique columns and Y-
shaped columns under seismic loading with
respect to displacement, base shear, storey drift,
stiffness and time period.
E. Interpretation of results and conclusion.
E. Scope of the Study
The scope of this study is as follows:
A. RC building is considered.
B. Linear elastic analysis is to be done on the
structures.
C. Column is modeled as fixed to the base.
D. Loading due to infill walls were taken into
account.
E. Time History Analysis is to be done to obtain
displacements.
F. Configuration of the Models
In the current study, buildings are modeled using the
finite element software ETABS. The analytical
models of the building include all components that
influence the mass, strength, stiffness and
deformability of structure. The building structural
system consists of beams, columns, and slab. The
non-structural elements that do not significantly
influence the building behavior are not modeled.
Modal analysis and seismic coefficient analysis are
performed on models. It is proposed to study the
effectiveness of oblique columns and Y-shaped
columns. The beam and column are modeled are two
nodded line element with 6 DOF at each node. The
slab is modeled using 4 nodded area elements.
In present work, reinforced concrete G + 5 storied
buildings with oblique columns and Y-shaped
columns are taken which has situated in zone V (very
severe zone), is taken for the study.
Details of models are shown below:
1. Model 1: G + 5 storied RC structure with Oblique
columns
2. Model 2: G + 5 storied RC structure with Y-
shaped columns
Table -1: Structural Data for both Models
Sr. No. Description Specifications
1 Type of Structure G + 5 Storied RC Structure
2 Structure Type Plan Regular Structure
3 Plan Dimensions 12 m X 12 m
4 Total Area 144 sq. m
5 Bay Width in Longitudinal Direction 4 m
6 Bay Width in Transverse Direction 4 m
7 No. of Bays in Longitudinal Direction 3 bays of 4 m length
8 No. of Bays in Transverse Direction 3 bays of 4 m length
9 Height of Building 19.2 m (G + 5 Storey)
10 Height of Each Storey 3.2 m
11 Plinth Height 1.2 m
12 Depth of Foundation 2 m
13 Size of Beams 230 mm X 450 mm
14 Size of Columns
C1 = 300 mm X 600 mm
C2 = 450 mm x 450 mm
15 Thickness of Slab 150 mm
16 External Wall thickness 200 mm
17 Internal Wall thickness 100 mm
18 Height of Parapet Wall 1 m
19 Density of Concrete 25 kN/m3

20 Concrete Grade M30
21 Grade of Steel Fe 500
22 Unit Weight of Concrete 25 kN/m3
23 Unit Weight of Steel 78.5 kN/ m3
24 Density of Brick Masonry 20 kN/ m3
The plan of model of G+5 storied RC Structure with oblique columns and Y-shaped columns is as follows:
Fig. 3 Plan of Model 1 and Model 2
Fig. 4 Elevation and Rendered View of Model 1 (G + 5 Storied RC Structure with Oblique Columns)
The oblique columns are modeled only at periphery. Internal columns remain vertical. There is not any change in
internal columns.
Fig. 5 Elevation of Model 2 (G + 5 Storied RC Structure with Y- shaped Columns)

The Y-shaped columns are modeled only at periphery. Internal columns remain vertical. There is not any change
in internal columns.
PERFORMANCE ANALYSIS
A. Loading on Model 1, Model 2 and Model 3
Table -2: Loading on Models
Sr.
No.
Loads Specifications
1
Self-Weight of the Frame elements &
slabs
It is calculated & used automatically during analysis by
the ETABS software
2
Super-Imposed Dead Load (IS 875 Part I
: 1987)
a) Floor Finish = 1.5 kN/m2
b) External Wall Load = 12.8 kN/m
c) Internal Wall Load = 6.4 kN/m
d) Parapet Wall Load = 4 kN/m
e) Water Proofing Load = 2 kN/m2
3 Live Load (IS 875 Part II : 1987)
a) Live Load for Floors = 3.0 kN /m2
b) Live Load for Roof = 4.0 kN /m2
4 Wind Load (IS 875 Part III : 2015)
a) Vb, Basic Wind Speed = 50 m/sec (Bhuj City)
b) Probability Factor, k1 = 1
c) Terrain Roughness and Height Factor, k2 = 1
(Terrain Category = III)
d) Topography factor, k3 = 1
e) Importance Factor, k4 = 1
Design Wind Speed, Vz = Vb . k1 . k2 . k3 . k4
Vz = 50 x 1 x 1 x 1 x 1
Vz = 50 m/sec2
Design Wind Pressure, Pz = 0.6 x Vz
2
Pz = 0.6 x 502
Pz = 1500 N/m2
= 1.5 kN/m2
5
Earthquake Load or Seismic Load (IS
1893 Part I: 2016)
a) City :- Bhuj (Gujrat)
b) Seismic Zone = Zone V (Very Severe Zone)
c) Zone Factor , Z = 0.36
d) Importance Factor, I = 1.2
e) Damping Ratio = 0.05 (5%)
f) Response reduction Factor, R = 5 (SMRF)
g) Soil Type = II, Medium or Stiff Soils
h) Seismic Source Type = B
i) Period in X – direction = 0.09h / √dx seconds = 0.50
seconds
j) Period in Y – direction = 0.09h / √dy seconds = 0.50
seconds
Where,
h = height of the building
dx = length of building in x direction
dy = length of building in y direction

B. Analysis Results of Model 1: G+5 Storied RC Structure with Oblique Columns
1. Maximum Storey Displacement
Graph 1 Graph of Maximum Storey Displacement
2. Maximum Storey Drift
Graph 2 Graph of Maximum Storey Drift
3. Base Shear
Graph 3 Graph of Base Shear along EQX & EQY

4. Maximum Storey Stiffness
Graph 4 Graph of Storey Stiffness along EQX
Table -3: Summary Results of Analysis Results of Model 1: G + 5 Storied RC Structure with Oblique
Columns
Sr.
No.
Parameter Load Case/Combo Direction Value
1
Maximum Storey
Displacement
[1.5 DL + 1.5 EQ (+Y)] Direction Y 6.3 mm
2 Maximum Storey Drift [1.5 DL + 1.5 EQ (+Y)] Max Drift Y 0.000162 mm
3 Base Shear EQ +X and EQ +Y Seismic X and Y 831.2117 kN
4 Maximum Storey Stiffness EQ +X 3 Story 1 1757254.595 (kN/m)
5 Time Period EQ +X & EQ +Y Seismic X and Y 0.5 sec
C. Analysis Results of Model 1: G+5 Storied RC Structure with Y-shaped Columns
1. Maximum Storey Displacement
Graph 5 Graph of Maximum Storey Displacement

2. Maximum Storey Drift
Graph 6 Graph of Maximum Storey Drift
3. Base Shear
Graph 7 Graph of Base Shear along EQX & EQY
4. Maximum Storey Stiffness
Graph 8 Graph of Storey Stiffness along EQX

Table -4: Summary Results of Analysis Results of Model 1: G + 5 Storied RC Structure with Oblique
Columns
Sr.
No.
Parameter Load Case/Combo Direction Value
1
Maximum Storey
Displacement
[1.5 DL + 1.5 EQ (+Y)] Direction Y 50.27 mm
2 Maximum Storey Drift [1.5 DL + 1.5 EQ (+Y)] Max Drift Y 0.000248 mm
3 Base Shear EQ +X and EQ +Y Seismic X and Y 1096.6801kN
4 Maximum Storey Stiffness EQ +X 3 Story 1 733562.715 (kN/m)
5 Time Period EQ +X & EQ +Y Seismic X and Y 0.5 sec
Table -5: Comparative Analysis Results of Model 1 and Model 2
Sr.
No.
Parameter
Values of Model 1
(Oblique
Columns)
Values of Model
2 (Y-shaped
Columns)
Difference
Percentage
Increase or
Decrease in Value
1
Maximum Storey
Displacement
6.3 mm 50.27 mm 43.97 mm 697.94
2
Maximum Storey
Drift
0.000162 mm 0.000248 mm
0.000086
mm
53.08
3 Base Shear 831.2117 kN 1096.6801kN
265.4684
kN
32.07
4
Maximum Storey
Stiffness
1757254.595
(kN/m)
733562.715
(kN/m)
-
1023691.8
8 (kN/m)
- 58.25
5 Time Period 0.5 sec 0.5 sec 0 0
Graph 9 Comparative Analysis of Model 1 and Model 2 with respect to Maximum Storey
Displacement
Graph 10 Comparative Analysis of Model 1 and Model 2 with respect to Maximum Storey Drift

Graph 11 Comparative Analysis of Model 1 and Model 2 with respect to Base Shear
Graph 12 Comparative Analysis of Model 1 and Model 2 with respect to Maximum Storey Stiffness
Graph 13 Comparative Analysis of Model 1 and Model 2 with respect to Time Period
CONCLUSION
Maximum Storey Displacement in oblique columns is
6.3 mm and in Y-shaped columns is 50.27 mm.
Results show that maximum storey displacement is
increased in Y-shaped Columns by 43.97 mm. It
means maximum storey displacement is increased in

Y-shaped columns by 697.94%. Hence oblique
columns give better results in storey displacement.
Maximum Storey Drift in oblique columns is
0.000162 mm and in Y-shaped columns is 0.000248
mm. The difference of maximum storeydrift between
oblique columns and Y-shaped is 0.000086 mm.
Maximum Storey Drift in Y-shaped columns is
increased by 53.08 % as that of oblique columns. The
lower base shear is getting in oblique columns and the
higher base shear is getting in Y-shaped columns.
Base shear in oblique column is 831.22 kN while
1096.68 in y-shaped column. It means that base shear
value is increased by 32.07% in Y-shaped column as
compared to oblique columns. The joint of the Y-
shaped holds to be weak under seismic loading.
Necessarily requires the strengthening the joins of Y-
shaped column. Maximum StoreyStiffness in oblique
columns is 171757254.595 kN/m and 733562.715 in
Y-shaped columns. Results of maximum storey
stiffness show that stiffness gets deceases in y-shaped
columns as compared to oblique columns. It is
decreased by 58.25%. Oblique columns offer best
resistance to lateral loads. Hence, it needs optimum
design procedure to proceed for further studies and
also for construction. In time period, there is no
change in both oblique columns and Y-shaped
columns. It remains same 0.5 sec in both columns.
The oblique columns and Y-shaped columns can be
used for architectural purpose by giving the pleasing
appearance to inclined support members, which
increases the aesthetic appearance of the structure.
Acknowledgement
At the end of our project, it is a pleasant task to
express our thanks to all those who contributed in
many ways to the success of this study and made it an
unforgettable experience for us. We would like to
express our sincere gratitude to guide Dr. P. L.
Naktode, for his excellent guidance and continuous
encouragement during course of our work. We truly
appreciate for his vast knowledge and delight
supervision and advice. Our special thanks to Dr. P.
L. Naktode, Head of Civil Engineering Department,
for his constant inspiration and all the facilities
provided to successfully complete this work. We
would also like to thank Dr. A. S. Maheshwari,
Associate Dean of the Institute who has provided us
this opportunity to present this dissertation. We would
also like to thank to all the faculty members of the
department for their valuable guidance and support
during the course of our work. Also we would like to
thank all our friends who have directly or indirectly
helped us in our project work throughout the course.
Finally we would like to thank our parents from
whom we learnt the value of hard work and its fruitful
results.
References
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