ISSN
Vol., Issue.,
April & May 2014,
Pages :
www.semargroup.org,
www.ijsetr.com
To Study Seismic Behaviour Of RC Building With
Floating Columns
NIKHIL BANDWAL 1, ANANT PANDE 2, VAISHALI MENDHE 3, AMRUTA YADAV 4
1
PG Scholar, Dept of CE, Yeshwantrao Chavan College Of Engineering, Nagpur , Maharashtra, India,
Email : nikhilbandwal10@gmail.com
2
Prof., Dept of CE, Yeshwantrao Chavan College Of Engineering, Nagpur , Maharashtra, India,
Email : apande_in@yahoo.com
3
Asst. Prof., Dept of CE, Yeshwantrao Chavan College Of Engineering, Nagpur , Maharashtra, India,
Email : vaishalimendhe@gmail.com
4
Asst. Prof., Dept of CE, Yeshwantrao Chavan College Of Engineering, Nagpur , Maharashtra, India,
Email : amruta_capricorn@yahoo.co.in
Abstract : Many building are planned and constructed with architectural complexities. The complexities include
various types of Irregularities like floating columns at various levels and locations. Buildings are critically analyzed for
the effect of earthquake. Earthquake load as specified in IS 1893 (part 1) : 2002 are considered in the analysis of
building.
A G+06 storied building with different architectural complexities such as External Floating Columns, Internal floating
columns and combination of Internal and External Floating columns is analyzed for various earthquake zones.
In over all study of seismic analysis, critical load combinations are found out. For these critical load combinations, Case
wise variation in various parameters like displacements, moments and Forces on columns and Beams at Various floor
level are compared and significant co-relationship between these values are established with Graphs. This Building is
Design and Analyse with the help of STAAD-Pro Software
Key Words - Architectural Complexities, Floating Columns, Seismic Zones, Seismic Reliability, Critical Load
Combinations.
Introduction : Buildings are symbol of modern city and
as such are a crowning achievement of structural
engineering. With the increasing pressure of population,
commerce and trade, the cost of land in cities have
raised. very high which results in increases in the
number of high rise buildings and also introduction of
floating column in different positions. As per the Indian
standard code the country is classified into different
zones for which it specifies the seismic zone factor and it
is very important to design the buildings for seismic
force to prevent the losses occurs due to earthquake.
Code of practice for earthquake engineering has been
designed with the aim that human lives are protected,
damage is limited and service structures remain
operational. In order to achieve this, A G+06 storied
building with different architectural complexities such as
External External Floating Columns, Internal floating
columns and combination of Internal and External
Floating columns is analyzed for various earthquake
zones.
Seismic Response of RC Frame Buildings with Soft
First Storeys: [Jaswant N. Arlekar] 1.
This Study Gives the importance of explicitly
recognizing the presence of Floating columns in the
analysis of the building.
Qualitative Review of Seismic Response of
Vertically Irregular Building Frames: [Devesh P.
Soni] 2. This study summarizes state-of-the-art
knowledge in the seismic response of vertically
irregular building frames.
Details of the structure are in following Table
Type of Structure
Area of individual
floor
Storey Height
Earthquake Zones
1
R.C. G+06 Building
2319. 30 Sq.ft.
2.8 m
IV, V
Type of soil
Lateral
Load
Resisting System
Though as per the IS 1893 (Part 1) – 2002, Analysis
parameters considered in the comparison of Ordinary
Moment Resisting Frame are
Medium
Ordinary
RC
moment-resisting
frame (OMRF)
Response Reduction
Factor, R
Live Load
1)
2)
3)
4)
5)
3.0
1.
2.
Dead load
3.
3 KN/m2
Self Wt. of
whole
Structure
Wt
.of
Brickwork
=13.34
KN/m
Slab Load =
3 KN/m2
Displacement in X and Z Direction
Axial Force in X-direction (Fx)
Shear in Z-direction (Fz)
Moment in X- direction (Mx)
Moment in Z- direction (Mz)
For analysis of structure, 7 load combinations were
considered
1)
2)
3)
4)
5)
6)
7)
1.5(DL+LL)
1.2(DL+LL+EQX)
1.2(DL+LL+EQZ)
1.5(DL+EQX)
1.5(DL+EQZ)
0.9DL+1.5EQX
0.9DL+1.5EQZ
However it was found that 2 load combinations are
critical for columns. These are 1.5(DL+EQX) or
1.5(DL+EQZ) depending on orientation of columns.
In the STAAD-Pro necessary precautions is taken to
take adequate zone factor and response reduction
factors depending on case.
For the comparison, Following columns are selected
1
Corner column and
2
Intermediate Column
Exclusive data of analysis for these columns and
Beams is exported to excel for further analysis and
comparison. Based on the data graphs are plotted .
Relations developed are given below
Typical Plan of Building
(Columns Refer All Floor)
Analysis and Comparison : The Building with
architectural complexities was analyzed for all the
conditions including Earthquake load. The building
chosen was 16.8 m high building. To study the effect
of various loads in various Earthquake zone the
building was modelled as per plan and the plan was
remodified in four different ways so that total number
of cases are four namely
1.
2.
3.
4.




Normal RC Building without any floating column.
RC Building with External floating columns.
RC Building with Internal floating columns.
RC Building With Internal and External Floating
columns.

2
Case Wise variation in X and Z
Displacement values for all Cases.
Case Wise variation in Axial Force Fx
values for all Cases.
Case Wise variation in Shear Fz values for
all Cases.
Case Wise variation in Moment Mx values
for all Cases.
Case Wise variation in Moment Mz values
for all Cases.
X –Displacement (Corner Column)
X –Displacement (Intermediate Column)
Graph - 1
Graph -2
Graph - 3
Graph -4
Z –Displacement (Corner Column)
Z –Displacement (Intermediate Column)
Graph - 5
Graph -6
Graph - 7
Graph -8
3
Axial Force - Fx (Corner Column)
Axial Force - Fx (Intermediate Column)
Graph - 9
Graph -10
Graph - 11
Graph -12
Force - Fz (Corner Column)
Force - Fz (Intermediate Column)
Graph - 13
Graph -14
Graph - 15
Graph -16
4
Moment - Mx (Corner Column)
Moment - Mx (Intermediate Column)
Graph - 17
Graph -18
Graph - 19
Graph -20
Moment - Mz (Corner Column)
Moment - Mz (Intermediate Column)
Graph - 21
Graph -22
Graph - 23
Graph -24
5
irregular RC Frame with stiffness irregularity at
fourth floor”, Volume 3, Issue 8, August 2013
3. Anibal Costa, Raimundo Del Gando, “Seismic
Behavior of Reinforced concrete frames with
setbacks”,
13th WCEE, August 1-6, 2004, Vancouver,
B.C., Canada
4. Vamvatsikos D. and Cornell C.A., Incremental
Dynamic Analysis, Earthquake Engineering
and Structural Dynamics, Vol.31, pp 491.514,
2002
5. Paulay, T. and Priestley, M.J.N., 1992, “Seismic
Design of Reinforced Concrete and Masonry
Buildings”, pp. 420-440
6. Bertero, V. V., “State of the Art in Seismic
Resistant Construction of Structures,” Volume
II , Chapter 17
7. Wallace, J. W.; McConnell, S. W.; Gupta, P.;
and Cote, P. A., “Use of Headed Reinforcement
in Beam-Column Joints Subjected to
Earthquake Loads,” ACI Structural Journal, V.
95, No. 5, Sept.-Oct. 1998, pp. 590-606.
8. A.G.Tsonos,
I.A.Tegos
and
G.Gr.Penelis[1992]. “Seismic resistance of
Type 2 Exterior Beam column joints reinforced
with inclined bars” The ACI structural Journal,
Title No.89S1, JanFeb 1992.
9. Altoontash, A., 2005. Simulation and Damage
Models for Performance Assessment of
Reinforced Concrete Beam-Column Joints,
Ph.D. Thesis, Stanford University.
10. Wallace, J. W.; McConnell, S. W.; Gupta, P.;
and Cote, P. A., “Use of Headed Reinforcement
in Beam-Column Joints Subjected to
Earthquake Loads,” ACI Structural Journal, V.
95, No. 5, Sept.-Oct. 1998, pp. 590-606.
Conclusion :
1.
2.
3.
4.
5.
6.
7.
Provision of
Case 2 (External Floating
columns) may Increase displacements at
various nodes.
Critical load combinations were found, are
1.5(DL+EQX) or 1.5(DL+EQZ) Depending on
position of floating columns.
With the provision of Case 4 ( External and
Internal Floating columns) and case 3(Internal
Floating Columns) may Increase Axial Force
Fx and Shear in z direction (Fz) at all floors.
Though it is observed that When section
properties in beam increases at that floor level,
partially contributes axial force Fx increasing
or decreasing at respective floors which can be
Observed in zone IV and V in Intermediate
Column.
Significant co relationship is observed in
between Case 2 and case 4 for Fz of the corner
column also we observed the same effect for
case 1 and case 3 too.
It is observed that case 4 (Internal and External
Floating columns) Increases the Mx and Mz
Values at all floors for All zones.
In all zones for case 2 (External floating
columns), Torsion at ground floor increases,
but thereafter floors, there is significant
reduction in torsion occurs.
References :
1.
2.
Onkar V. Sapate, “Inter-relationship Between
moment values of columns in Building with
different architectural complexities and
different
seismic
zones”,Vol.2,
Issue
2(December 2012) pp. 55-59
Shaikh Abdul Aijaj Abdul Rahman, Girish
Deshmukh, “Seismic response of vertically
6