A STUDY ON SEISMIC PERFORMANCE OF ADJACENT
STRUCTURES CONNECTED WITH FLUID VISCOUS DAMPERS
1
1
AVINASH A.R., 2PADIGELA ABHINAI, 3KARTHIK.B, 4KIRAN KAMATH
Assistant professor, Department of Civil Engineering, Manipal Institute of Technology, Manipal University, Manipal
2,3
Post Graduate student, Manipal Institute of Technology, Manipal University, Manipal
4
Professor, Department of Civil Engineering, Manipal Institute of Technology, Manipal University, Manipal
E-mail: 1abhinaipadigela@gmail.com
Abstract— Seismic performance of two adjacent buildings connected with Fluid Viscous Dampers (FVDs) has been studied
in the present work. 3D models of two adjacent buildings are developed using the software ETABS® evaluation version.
Height of one building (h) is kept constant at 15 m, whereas the height of adjacent building (H) is varied by increasing the
number of storey’s. The H/h ratio is called as height ratio, this ratio is varied from 1 to 3. The adjacent structures with and
without FVD connections are subjected to accelerograms of different earthquakes. FVDs are connected at storey levels of
both the buildings. Responses of the adjacent structures are compared with and without FVD connections. Responses
considered in the study are roof displacements, roof accelerations and base shears. Results indicate that adding FVDs have
modified seismic responses of connected structures.
Keywords— Time history, Fluid Viscous Dampers, Height ratio(H/h).
In order to obtain damping coefficients required for
the present study, a method given by Tande and
Shinde[4] has been adopted. In their study, an optimal
distribution of viscous dampers has been obtained for
connected adjacent buildings. As per the study,
damping coefficient(Cd) of the damper should be
such a way that when the value is increased beyond
certain point, it should not affect the response of the
building any more i.e., after reaching an optimum
value, even if, the value of Cd is increased, it is not
going to alter or reduce the response of the building
any more.
A study conducted by Jinkoo kim et al.[5] has stated
that the effectiveness of the Visco-Elastic Dampers
connected to the adjacent structures is more when the
natural frequencies of the structures are different
enough. Xu et al.,[6] performed a study on adjacent
buildings connected withFVDs. For the study, two
adjacent buildings of same heights and two adjacent
buildings of different heights have been considered.
The study states that the dampers are more effective
when height of one of the connected structures is
much less than the other.
Literatures indicate that the effect of gradual height
variation has not been studied and hence in the
present study, height of adjacent building is varied by
varying number of storeys. Two 3D buildings
connected with FVDs at storey levels are considered
and the height of one building is varied to study the
effect of FVDs on dynamic characteristics of these
buildings.
Ι. INTRODUCTION:
Lack of space in urban areas has created tendency of
building tall structures closer to each other.
Earthquakes pose a great threat to these structures as,
the effect of earthquake may create a situation
wherein, these adjacent buildings pound with each
other and can cause severe damage to each other.
International building code (IBC) [1] has given
guidelines on maintaining a minimum distance
between the adjacent buildings to avoid seismic
pounding.However, Mehmet Eren Uz[2] has found
that the dynamic behavior of buildings can be
enhanced by connecting adjacent structures with
Fluid Viscous Dampers (FVDs). FVDs are
supplemental damping devices which dissipate
energy with the help of damping mechanism. FVDs
have been widely used in structures for retrofitting.
FVDs reduce both stress and deflection
simultaneously within a structure subjected to ground
motion. This is due to the fact that, force in FVD
varies depending on the relative velocity at its ends
which produces a response which is inherently out of
phase with stresses due to flexing of the structure.
FVDs can be installed in both new and existing
structures. Since FVDs are relatively small in size,
they can be added without significant modification to
the structure.
FEMA(Federal Emergency Management Agency)
273[3] has given the governing equation of a FVD
as,
ΙΙ. METHODOLOGY
For the study two 3Dadjacent RC frame structures
connected with FVDs are developed and analyzed
using ETABS® software. Columns and beams are
modelled as frame elements having cross sectional
dimensions of 600mm × 450mm and 600mm ×
350mm respectively. Spacing between two buildings
Where, F= Force in the dampers,Co= damping
coefficient,|D|= relative velocity between the ends of
the device,n= damping exponent of the device(in case
of linear dampers, n=1), Sgn is the signum function
which indicates the sign of the relative velocity term.
Proceedings of 11th IRF International Conference, 8th May 2016, Hyderabad, India, ISBN: 978-93-86083-09-8
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A Study on Seismic Performance of Adjacent Structures Connected With Fluid Viscous Dampers
is 3m. Height of each storey is 3m. The floor slabs
are 200mm thick. Gravity loads include self-weight
of the structure and live load of 2kN/m2. FVDs are
modelled as link elements and effective stiffness of
the FVDs is set to zero in order to achieve pure
damping. For all the structural elements, M30
concrete and Fe415 steel are considered. Height of
one building is kept constant whereas, height of
second building is varied based on H/h ratio where
‘H’ is the total height of the second building and ‘h’
is the total height of the first building. In the present
study, H/h ratios are obtained by varying second
building height keeping the first building height
constant. The plan and elevation of the structures
corresponding to a configuration with height ratio of
2 are shown in figures 1 and 2 respectively.
For the present work, required values of the damping
coefficients (Cd) of FVDsare obtained based on a
study by Tande and Shinde[4]. As per the study,
response of a structure is obtained by varying the
values of ‘Cd’. The value of damping coefficient is
varied until there is no change in response of the
structure which indicates that the effectiveness of the
damper seizes to exist beyond certain value of ‘Cd’.
The process is repeated for all the height ratios of the
buildings to obtain all damping coefficients.
In the study three different accelerograms are
considered. The acceleration time histories used for
the analysis are taken from records of earthquakes
which occurred in the California region of USA.
Dampers
Fig2: Elevation
Fig3: Accelerogram of LA03
Fig4: Accelerogram of LA06
Fig5: Accelerogram of LA14
Fig1: Plan of buildings connected with FVDs
III. RESULTS AND DISCUSSIONS:
The first two accelerograms, LA03 (El Centro Array
5, James Road)( LA stands for Los Angeles) and
LA06 (El Centro Array 6) are taken from the1940 El
Centro earthquake with a peak ground acceleration
(PGA) of 0.386g and 0.23g respectively. The third
accelerogram LA14 (Northridge, LA County Fire
Station) is from the 1994 Northridge earthquake with
a PGA of 0.64g. Accelerograms of these earthquakes
are shown along with PGAs in figures 3, 4 and 5
respectively. Models are subjected to time history
analysis and response of structures in terms of roof
displacement, acceleration and base shearare studied
before and after the connection with the FVDs.
Response of the connected and unconnected
structures (with the height ratios varying from 1 to 3)
subjected to accelerograms LA03, LA06 and LA14
are obtained in terms of roof displacements, roof
accelerations and base shear.
The required damping coefficients of the connecting
FVDs obtained are listed in the table 1.
From figure 6 it can be observed that there is a
significant reduction in peak roof displacement when
adjacent structures are connected with FVDs for
LA03 accelerogram.
Proceedings of 11th IRF International Conference, 8th May 2016, Hyderabad, India, ISBN: 978-93-86083-09-8
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A Study on Seismic Performance of Adjacent Structures Connected With Fluid Viscous Dampers
It can be observed from figure 7 that there is a
significant reduction in the peak roof acceleration of
buildings for all height ratios ranging from 1 to 3.
The figure 8 indicates the variation of Base Shear of
the buildings along with the height ratios(H/h) under
accelerogram LA03. Thus it is observed how the
extent of Base Shear reduction varies with the height
ratios(H/h).Similar plots can be obtained for LA06
and LA14 as well.
Table 2, 3 and 4 lists the response reductions for
LA03, LA06 and LA14 respectively. Reduction in
response was observed in every case(LA03, LA06
and LA14) for all the height ratios. It can be seen
from tables that the peak reduction in roof
displacement is 78.59% for building 1 for LA14
earthquake. For building 2 the peak reduction in roof
displacement was observed to be 85.93% for LA14
earthquake.
It is also seen that the peak reduction in roof
acceleration is 84.48% for building1 for LA14
earthquake. For building 2 the peak reduction in roof
acceleration was observed to be 85.87% for LA14
earthquake.
It is observed from the tables that the peak reduction
in base shear is 76.94% for building 1 for LA14
earthquake. For building 2 the peak reduction in base
shear was observed to be 81.14% for LA03
earthquake.
Fig6:Variation of peak roof displacement of building for
different height ratios
a) Building1
Table1: Required damping coefficients for
connecting the buildings according to the height
ratios
b) Building 2
Fig7:Variation of peak roof acceleration of building with
different height ratios
Fig8:Variation of Base Shear of buildingwith different height
ratios
a) Building 1
Proceedings of 11th IRF International Conference, 8th May 2016, Hyderabad, India, ISBN: 978-93-86083-09-8
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A Study on Seismic Performance of Adjacent Structures Connected With Fluid Viscous Dampers
Table2: Percentage reduction in response of FVD connected adjacent structures for LA03
Table3: Percentage reduction in response of FVD connected adjacent structures for LA06
Table4: Percentage reduction in response of FVD connected adjacent structures for LA14
indicates a lesser seismic force being attracted by
building 2.
CONCLUSIONS
Results indicate that the dynamic behavior of the
building 2 has sustainably enhanced by connecting to
building 1 with FVDs.
A considerable reduction is observed in the peak roof
displacement and peak roof acceleration of both the
buildings. A significant reduction in base shear
ACKNOWLEDGEMENT
The authors would like to express their sincere thanks
to Department of Civil Engineering, Manipal Institute
of Technology, Manipal and Manipal University for
Proceedings of 11th IRF International Conference, 8th May 2016, Hyderabad, India, ISBN: 978-93-86083-09-8
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A Study on Seismic Performance of Adjacent Structures Connected With Fluid Viscous Dampers
providing guidance and facilities required for the
present study.
[4]
REFERENCES
[1]
[2]
[3]
International Building Code(IBC):2003 International
Code Council, USA.
Mehmet Eren Uz.,(2009)"Improving the dynamic
behavior of adjacent buildings by connecting them with
fluid viscous dampers". University of Wollongong.
Federal Emergency Management Agency-ASCE.FEMA
274-“NEHRP commentary on the NEHRP guidelines
[5]
[6]
for the seismic rehabilitation of buildings”. Washington,
DC: Federal Emergency Management Agency-ASCE,
1997.
Tande, S.N. and Shinde, D.N.(2008). Optimal Seismic
Response of Adjacent Coupled Buildings with
Dampers. 14 WCEE: 14th World Conference on
Earthquake Engineering Conference Proceedings.
Beijing, China.
Jinkoo kim,, Jingook Ryn and Lan chung., (2005)
“seismic performance of structures connected by Visco
Elastic Dampers”.
Y.L.Xu, Q.He and J.M.Ko., (1997) “Dynamic
properties of damper connected adjacent buildings”.
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Proceedings of 11th IRF International Conference, 8th May 2016, Hyderabad, India, ISBN: 978-93-86083-09-8
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