International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 1203–1210, Article ID: IJCIET_10_04_126
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJCIET&VType=10&IType=4
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
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DYNAMIC ANALYSIS OF THE BASE ISOLATED
TUBULAR TALL BUILDING SYSTEM (LEADRUBBER BEARING) IN ETABS
Aamir Riyaz Dar
P.G. Student, Department of Civil Engineering, Chandigarh University,
Mohali, Punjab, India
Simranjit Singh
Assistant Professor Department of Civil Engineering, Chandigarh University,
Mohali, Punjab, India
ABSTRACT
In case of dynamic analysis of tall buildings, the various important dynamic
characteristics of tall building namely, the natural frequency (ω, radians/second) or
simply time period (T, seconds),lateral displacement, base shear and overturning
moment of tall buildings using ETABS software. In this paper, an approximate
procedure is generated to perform the seismic analysis of simple and tubular tall
building system with base isolation (lead-rubber bearings) system and the outcome
compared with the results obtained without base isolation (lead-rubber bearing) of
tall buildings. Base isolation system is basically a passive control device which
decouples the super structure from substructure resting ground motion by insinuating
structural elements with low horizontal stiffness between the structure and foundation.
This analysis of G+29 rigid joint plane RCC frame has for four cases. First case is
simple RCC frame with fixed base and with base isolation (LRB), second case is
simple tube RCC frame with fixed base and with base isolation (LRB), third case is
tube in tube system RCC frame with fixed base and with base isolation (LRB) and
fourth case is bundle tube system RCC frame with fixed base and with base isolation
(LRB) .The effectiveness of base isolation in every cases is compared with simple
frame and tubular system cases. This analysis is done by using ETABS software and
for design purpose of base isolated system 1893:2002 (part 1) and for seismic design
of isolated structures (F.Naeim and J.M.Kelly).
Key words: Base isolation, Lead-rubber bearing (LRB), Response spectrum analysis,
Time period, Lateral displacement, Base shear, Overturning moment.
Cite this Article: Aamir Riyaz Dar and Simranjit Singh, Dynamic Analysis of the
Base Isolated Tubular Tall Building System (Lead-Rubber Bearing) in ETABS,
International Journal of Civil Engineering and Technology 10(4), 2019, pp. 1203–
1210.
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Dynamic Analysis of the Base Isolated Tubular Tall Building System (Lead-Rubber Bearing) in ETABS
1. INTRODUCTION
The tall structure is commonly characterized as one that is taller than the most extreme
tallness which individuals are happy to stroll up; it thus requires mechanical vertical
transportation. This incorporates a somewhat constrained scope of building utilizers,
principally private condos, inns, and places of business, however at times including retail and
instructive offices. A sort that has appeared recently is the blended use of buildings, which
contains shifting measures of private, office, lodging, or business space. Tall structures are
among the biggest structures fabricated, and their unit costs are generally high; their business
and office capacities require a high level of adaptability. The establishment of tall structures
bolster exceptionally overwhelming burdens, yet the frameworks produced for low-ascent
structures are utilized, however augmented in scale. These incorporate solid caisson columns
bearing on sake or expanding on uncovered sake itself. Bearing heaps and coasting
establishments are additionally utilized. Multi-story structures are utilised for office,
unpredictable, private pads, open focuses, and so on. There is requirement for multi-story
working due to congestion of urban areas. There multi-story structures can be changed into
tall structures so as to accomplish more floor space yet involves less land space. In the plan of
tall structures, parallel burdens are wind load and seismic load. There are different parallel
burden opposing frameworks, for example, supporting edge framework, minute opposing
edge framework, outline bracket cooperating framework, shear divider framework, centre and
outrigger framework and tubular framework.
The tube is name given where you oppose the horizontal loads (seismic or wind) a
building is intended to act like a three dimensional empty cylinder, cantilevered opposite to
ground. The framework was present by Fazlur Rahman Khan. Tube frame development was
first utilised in the Dewitt-Chestnut Apartment building, Structured by Khan and finished in
Chicago in 1963.thus, most of the structures more than 40 stories built since the 1960s are of
this basic sort.
The most effective impact on building is mainly due to earthquakes in the resent past have
given the intention about seismic protection to the building structure. This has given the
confinement to different advanced techniques to protect the building structure from the
earthquake. The base isolation system is one of the best technique in which base isolators are
provided at the base of building which separates the building from ground motion provide
stiffness to the building in vertical direction and flexibility in horizontal direction.
1.1. Regular Types of Structural System in Tall Buildings

Unbending frame system

Braced casing framework

Shear wall system

Coupled wall system

Advanced structural tubular system
Tubular system: - The tubular system or cylindrical framework is to organize the auxiliary
components so that the formwork can oppose the forced loads on the structure proficiently
particularly the horizontal burdens. This framework includes different components for
example pieces, beams, supports, columns. The dividers and centres are locked in to oppose
the sidelong loads, in the rounded framework the even loads are opposed by section and
spandrel beams at the border dimension of the cylinders (tubes).
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Aamir Riyaz Dar and Simranjit Singh
Sorts of tubular system

Simple tube structure

Tube in tube structure

Bundle tube structure

Braced tube structure
The tube system idea depends on the possibility that a structure can be intended to oppose
lateral loads by planning and designing it as hollow cantilever perpendicular to the ground in
the least complex manifestation of the tube, the border of the outside comprises of firmly
divided columns that are integrated with profound spandrel beams. The combination of beams
and columns form a rigid frame that acts like composite heavy wall along the outside of the
structure.
2. RESPONSE SPECTRUM METHOD
Seismic analysis is the combination of both structural investigation and estimation of the
response of a structure to earthquakes. It is one of the important segments of structural
designing in locals where seismic tremors are predominant. For analysis described in this
guide, you have static and dynamic loads. The dynamic properties of structure are modelled in
ETABS using response spectral analysis. In this method, during earthquake the peak response
of structure is found directly from earthquake response spectrum. The multiple modes of
building response to an earthquake are taken in account and each model is combined in this
method to estimate the total response of structure. This model combination is to be made by
using either complete quadratic combination or square root of the square method. The model
values in case response spectrum analysis should be in range of effective damping of isolated
system or 30 present of critical, whichever is less. In this analysis synchronous excitation of
the model is done in both horizontal directions by considering 100 present of ground motion
and 30 present of the ground motion in perpendicular direction to calculate the design
displacement of isolated system.
3. MODELING AND ANALYSIS OF BUILDING USING SOFTWARE
(ETABS)
The purpose of present study is to compare the overall structural performance of simple,
tubular, and base isolated system for stabilization G+29 RCC building having symmetry
along X and Y direction with rectangle shape 30mX20m in all models against seismic force.

Using base isolation: -Story shear, Base shear and Story drift reduced after the lead rubber
bearing (LRB) is provided as base isolation system.

Using tubular system:-Allows greater flexibility, Regularity in the column, Seismic resisting
system and identical framing for all floors in building frame.
3.1. Design of Lead Rubber Bearing
As per IS: 1893:2016 and design procedure mentioned in reference [1] as follows:
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Dynamic Analysis of the Base Isolated Tubular Tall Building System (Lead-Rubber Bearing) in ETABS
Table 1.Design specifications of LBR for simple and tubular RCC building models
S.No.
Properties of lead rubber bearing
1. Required stiffness ,U2 & U3 (linear
properties) (kN/m)
2. Horizontal stiffness, U2&U3 (non-linear
properties)(kN/m)
3. Vertical stiffness, U1
(kN/m)
4. Yield strength, F
(kN)
5. Stiffness ratio (Post yield)
6. Effective Damping (KN-s/m)
Simple RCC frame
7743.61
Tubular RCC frame
8123.117
2363.82
2486.17
2740420.35
2943387.35
41.9457
44
0.1
0.05
0.1
0.05
3.2. Model Specification
Thirty story building was examined for validation. The various model plans of G+29 story
building, where each model with fixed and base isolated system are shown in figure 2.
Figure 1 Plan for G+29 storey models simple, tube in tube, bundle tube and simple tube.
The various models composed of two building RCC frame systems (simple and tubular
system) load, ground and building details are given as.
Table 1. Load and ground properties for all building models
Live load
(kN/m)
Super dead load
(kN/m)
Wall load
(kN/m)
Zone
Soil profile
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3(kN/m)
3(kN/m)
15(kN/m)
4
Medium sites
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Table 2 Model details
S.No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
9.
10.
Model details
NO. of story
Area of building base grid
Typical Story height (m)
Bottom story height (m)
Beam size (mm)
Spandrel beam (mm)
Column size (mm)
Slab thickness
Concrete grade
Steel grade
Zone factor
Simple RCC Frame
Fixed
Base isolated
30
30 X 20 m
3m
4m
0.650 X 0.400 m
No
0.8 X 0.8 m
0.150 m
M35
Fe500
0.24
Tubular RCC Frames
Fixed
Base isolated
30
30 X 20 m
3m
4m
0.650 X 0.650 m
1.2 X 0.450 m
0.8 X 0.8 m
0.200 m
M40
Fe500
0.24
4. RESULTS
Max. Lateral displacement in
mm
The results are based on model analysis, where we have four different structures with unique
specification of each model. The dynamic analysis of models with fixed base and base
isolated is carried out by using response spectrum method. So, we have total eight models and
we compare the results for time period, lateral displacement, base shear and overturning
moment.
140
120
100
80
60
40
20
0
lateral displacement in
x-direction
lateral displacement in
y-direction
WITHOUT BASE-ISOLATION(LRB)
Max. Lateral deflection in mm
Figure 2 Maximum Lateral Deflection
200
150
100
50
Lateral deflection in xdiection
0
lateral deflection in ydirection
WITH BASE-ISOLATION(LRB)
Figure 3 Maximum Lateral Deflection
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TIME PERIOD (sec.)
Dynamic Analysis of the Base Isolated Tubular Tall Building System (Lead-Rubber Bearing) in ETABS
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
TIME PERIOD OF BUILDING
MODEL WITHOUT BASE
ISOLATION (LRB)
TIME PERIOD OF BUILDING
MODEL WITH BASE
ISOLATION(LRB)
Max. BASE SHEAR (kN)
Figure 4 Time Period
5800
5600
5400
5200
5000
4800
4600
4400
BASE SHEAR IN X-DIRECTION
WITHOUT BASE
ISOLATION(LRB)
BASE SHEAR IN Y-DIRCTION
WITHOUT BASE
ISOLATION(LRB)
WITHOUT BASE ISOLATIOON (LRB)
Max. BASE SHEAR (kN)
Figure 5 Maximum Base Shear
6000
5000
4000
3000
BASE SHEAR IN X-DIRECTION
WITHOUT BASE
ISOLATION(LRB)
2000
1000
0
BASE SHEAR IN Y-DIRCTION
WITHOUT BASE
ISOLATION(LRB)
WITH BASE ISOLATIOON (LRB)
Figure 6 Maximum Base Shear
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Table 3 Overturning moment [without base isolation (LRB)]
Sr.no.
1
2
3
4
Type Of Model
Simple RCC frame
Simple tube
Bundle tube
Tube-in-tube
Eqx
X-Dir
kN-m
7.563E-06
6.563e-06
3.291E-06
6.596E-06
Y-Dir
kN-m
360771.9617
384338.8825
327134.3302
384612.4253
Eqy
X-Dir
Y-Dir
kN-m
kN-m
377385.2781 7.321E-06
340410.645
7.534e-06
343416.695
3.1E-06
340830.432
7.569E-06
Table 4 Overturning moment [with base isolation (LRB)]
Sr.no.
1
2
3
4
Type Of Model
Simple RCC frame
Simple tube
Bundle tube
Tube-in-tube
Eqx
X-Dir
kN-m
1.05E-05
2.0998
1.18E-06
4.21E-06
Y-Dir
kN-m
237256.59
300283.2398
273601.7191
274369.90
Eqy
X-Dir
kN-m
236008.79
265193.36
299131.67
263131.00
Y-Dir
kN-m
9.89E-06
1.82714
1.07E-06
5.93E-06
5. CONCLUSIONS
From the results following conclusion were arrived.

Maximum lateral deflection increases after providing base isolation (LBR) in G+29 story
simple RCC frame and tube in tube building model, but in case of simple tube and bundle tube
building model the maximum lateral displacement shows very less increment in comparison to
simple RCC frame and tube in tube building models show in fig.

The time period in all models like simple RCC frame, simple tube, bundle tube and tube in
tube decreases about 24%, 13%, 10% and 26% after providing base isolation (LBR) in
models as shown in fig.

After providing base isolation system (LBR) in every model base shear decreases between
10% to 30% as shown in fig which make the building stable against dynamic forces.

The overturning moment also decreases after analysing the models due to base isolation
system providing base isolation system (LBR) as shown in tables.
Finally we conclude that after dynamic analysing of all the models of G+29 story frame
buildings by the use of ETABS software every model shows different changing properties in
both cases with and without base isolation. Hence, the earthquake impact is reduced by the
use of lead rubber bearing is an effective base isolation technique.
REFERENCES
[1]
Minal Ashok, Somwanshi and.Rina N. Pantawane, Seismic Analysis of Fixed Based and
Base Isolated Building Structures, July 2015.
[2]
Zanaica L.,“Design of Storey-Isolation System in Multi-Storey Building” MEEES
programmed, May,2007.
[3]
Prashika Tamang, Bijay Kumar Gupta et al. (2016), Study on earthquake resistant
building-( Base Isolation).
[4]
Salic R. B., Garevski M. A. And Milutinovic Z. V., “Response of Lead-Rubber Bearing
isolated Structure,” The 14th World Conference on Earthquake Engineering, October 1217, 2008, Beijing, China.
http://www.iaeme.com/IJCIET/index.asp
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Dynamic Analysis of the Base Isolated Tubular Tall Building System (Lead-Rubber Bearing) in ETABS
[5]
Kilar V. And Koren D., “Usage Of Simplified N2 Method For Analysis Of Base Isolated
Structures,” The 14th World Conference on Earthquake Engineering, October 12-17,
2008, Beijing, China.
[6]
Saiful Islam A. B. M., Jameel M., Ahmad S.I. And Jumaat M. Z., “Study On Corollary of
Seismic Base Isolation System On Buildings With Soft Storey,” International Journal of
the Physical Sciences Vol. 6(11), pp. 2654-2661, 4 June, 2011
[7]
Jignesha Patel, Roshni J John, Seismic analysis of frame tube structure, International
Journal of Scientific & Engineering Research, December-2015, Volume 6, Issue 12.
[8]
Sharadrao Patil and UttamKalwane, Shear Lag in Tube Structures, International Journal of
Innovative Science, Engineering& Technology, March 2015, ISSN 2348 – 7968, Vol. 2
Issue 3.
[9]
Jagadish J. S , Tejas D. Doshi, A Study On Bracing Systems On High Rise Steel
Structures, International Journal of Engineering Research & Technology (IJERT)
July – 2013, ISSN: 2278-0181, Vol. 2, Issue 7.
[10]
Swapnil Ambasta, Dushyant sahu, and G.P. Khare, Analysis of the Base Isolated Building
(Lead Plug Bearing) in Etabs.
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