Seismic Performance of Reinforced Cement Concrete Structures with and Without Viscous Dampers

International Journal of Trend in Scientific Research and Development (IJTSRD)
Volume 4 Issue 2, February 2020 Available Online: www.ijtsrd.com e-ISSN: 2456 – 6470
@ IJTSRD | Unique Paper ID – IJTSRD30122 | Volume – 4 | Issue – 2 | January-February 2020 Page 769
Seismic Performance of Reinforced Cement Concrete
Structures with and Without Viscous Dampers
Rahul Tahilyani1, Dilip Budhlani2
1M. Tech Student, 2Assistant Professor,
1,2Department of Civil Engineering, G.N.I.T, Nagpur, Maharashtra, India
ABSTRACT
Passive energy dissipation have been used so far to dissipate the unwanted
energy due to earthquake and heavy wind actions. The complete failureofthe
structures that has occurred in the past due to catastrophic earthquakes may
be avoided with the use of such devices. The studyisconcernedwiththeuseof
accordion metallic dampers that uses hysteretic energy to dissipate the
unwanted energy due to earthquake. It consists of corrugated thin wall tubes
installed as a brace connection in the frame. The axial deformation of the
accordion damper enhances the lateral buckling capacity and results in
maximum reduction of the damaging measures.Thestudyemphasizestheuse
of such dampers and in-depth analysis is performed bysubjectingthebuilding
to base excitations in order to assess the nonlinear performance of the
dampers installed in the building
Keywords: Passive energy dissipating device, Base excitation, Damaging
measures
How to cite this paper: Rahul Tahilyani |
Dilip Budhlani "Seismic Performance of
Reinforced Cement Concrete Structures
with and Without Viscous Dampers"
Published in
International Journal
of Trend in Scientific
Research and
Development
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6470, Volume-4 |
Issue-2, February
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INTRODUCTION:
The philosophy in the conventional seismic design is that,
structure is designed to resist the lateral loads
corresponding to wind and small earthquake by its elastic
action only, and the structure is permittedtodamage but not
the complete collapse when it is subjected to a lateral load
associated with moderate or severe seismic events. As a
result, plastic hinges in the structure must be developed in
order to dissipate the seismic energy when the structure is
subjected to severe shakings. The design methods on this
philosophy are acceptable to account for needs for both
economic consideration and life safety. However, the
development of the plastic hinges relies on the large
deformation and the ductility of the structure. If the
structure is more ductile, it undergoes more deformation
and more damage it suffers. Besides, some important
structures such as hospitals have to remain in function after
the major earthquake; the former mentioned design
philosophy (life safety based) may notbeappropriate.These
structures should be strong enough to resist large
displacement and acceleration so that they can maintain
their function when excited by severe ground motions.
Structural passivecontrol systemshavebeendeveloped with
the design philosophy differentthantheconventional design
seismic design method, which have immediate effect of
increasing the critical damping ratio right up 25-30 %
(against 5% value usually used for metal structures) and at
the same time reducing the response of the structure during
seismic event.
Dampers are classified as follows:
1. Viscous Dampers
2. Visco-Elastic Dampers
3. Friction Dampers
4. Mass Dampers
5. Metallic Dampers
These are passive dampers which do not require external
power or energy to actuate during seismic event.Depending
upon the intensity of lateral forces acting on a structure it
dissipates seismic energy thus reducing inter-storey drift
and bending moment induced in the structure.
WORKING PRINCIPLE
Viscous damper consists of a cylinder and a stainless-steel
piston. The cylinder is filled with silicone fluid. The damper
is activated by the flow of silicone fluid between the
chambers at the opposite ends of the unit through small
orifice. Figure 1 shows the longitudinal cross section of
viscous damper.
IJTSRD30122

International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
Figure1 Longitudinal Cross-section of a fluid damper
It consists of piston rod which moves to and fro depending
upon the lateral force induced during an earthquake. High
strength seal is used to avoid leakage of the fluid. Now to
understand the mechanism how damper works. Let us
assume that the piston rod is moving from left to right as
seen in figure 1 (device subjected to compressive force).
Fluid flows from chamber 1 to chamber 2. Accordingly, the
force developed will be the pressuredifferential inthesetwo
chambers. However, the fluid volume is reduced by the
product of travel and piston rod area. Since the fluid is
compressible the amount of volumereducedisaccompanied
by the development of the restoring (spring like) force. This
phenomenon can be prevented by either using an
accumulator. This restoring force helps in reducing the
response of the structure during an earthquake. Theviscous
dampers can be attached to existing or new structure as a
bracing element as shown in figure 2.
Figure2 FVD as a toggle brace element
CASE STUDY
Study is carried out by selecting 3DRCCbuilding,modeled in
FE based software i.e. SAP 2000. Suitable shape plan and
elevation of the building has been chosen and it is kept
square shaped. Thorough study has beenconductedinorder
to understand theworkingof dampersunderbase excitation.
Total two sets of earthquakes of varying PGA have been
chosen and provided as an input to SAP 2000 by creating a
text file of ground acceleration data. Modal time history
analysis also known as fast non-linear analysis (FNA) has
been performed using above mentioned earthquakes for
comprehensive analysis of building with and without non-
linear FVD’s. Table 1 shows the details of the earthquakes
undertaken for the study. Damping ratio considered for all
modes of vibration is 5%.
Table1 Details of components of Earthquake
Station
Name
Earthquake
Peak
Acceleration (g)
Oakland Harbor
Wharf
Loma Prieta 0.27
Talf Lincoln
Tunnel
Kern County 0.16
Figure 3 shows the Plans and elevation of the building
considered for the analysis, assuming fixed basecondition at
the foundation. The plan area of the square building is kept
6.92 x 6.92 m. Height of each storey is kept uniform i.e. 3 m.
The details of remaining components of the building are
given in Table 2. The slab thickness is consideredas125mm
for all floors and diaphragm has been assigned at each floor
so as to simulate rigidity offered due to slab action. Wallsare
provided at outer periphery of thickness 230 mm. Concrete
of grade M 25 and steel Fe 415 is used to model the building.
In the present paper, only analysis is restricted to square
shaped building. After modeling the building, it is run for
modal analysis and the fundamental dynamiccharacteristics
of the building such as time period and mode shapes of the
buildings are studied.
Table2 Detail of Components of Square Building
Beam Size (mm) Column Size (mm)
B1 230 x 350 1 300 x 300
B2 230 x 350 2 400 x 400
3 450 x 450
Figure3 Elevation and plan of building

The size of beam and column are chosen in such a mannerto
satisfy the limit state of collapse. The buildingisdesigned for
gravity loading combinations using IS 456:2000. The basic
aim of the analysis is to study the dynamic behavior of the
building with and without damper. Initially, in order to
obtain the dynamic characteristics, time period and mode
shapes are determined with the help of FE based software
i.e. SAP 2000. The wall is provided on the outer periphery of
the building, live load is assumed to be 3 kN/m2 using the
provision of IS 875: 1987 part I and II. The building is
assumed to rest on hard strata in seismic zone IV of India.
The earthquake loading is applied at the base of the
structure by using the earthquake accelerationdata which is
fed in SAP 2000 in the form of text file. The software has
inbuilt function through which non-linear Time History
analysis can be formed. The analysis of structure equipped
with damper can be assessed very well by this method.
Modal time history analysis is adopted to carry out analysis.
Figure 4 shows the natural time period and mode shapes of
the square shaped building, moreover there is no change in
dynamic characteristics of building equipped withdampers.
Total 6 dampers were equipped at the base of the building.
Figure4 Natural time period and mode shapes of the
square shaped building
Initially, time history response of top storey displacement is
analysed with and without dampers, it was found that top
storey displacement is reduced to a great extent. Figure 5
shows the time history response of top storey displacement
of square shape building. This reduction clearly states that
the reduction in damage caused during earthquake without
dampers.
Figure 5 Time History Response of Top Storey
Displacement
As Earthquake is transient loading, the damaging measures
also changes with time, the time history responseofbending
moment of bottom storey column is checked with and
without damper, it was found that bending moment reduces
by almost 30% to 35%, which clearly signifies the potential
of dampers in minimizing the critical damaging response of
structure. Figure 6 shows the time history response of
bending moment with and without dampers.

Figure6 Time History Response of Bending Moment
Further, Force – Displacement relation isworkedout,whose
area give the amount of work done by dampers during
damping action. Figure 7 shows the hysteresis curves of
damper which shows viscoelastic behaviour.
Figure7 Hysteretic curve of damper
Finally, energy curves of the building with damper is shown
in Figure 8 it can be seen that damper dissipates much of
earthquake energy, thus avoiding complete yielding of
structure.
Complete damage may be avoided by using such Passive
Energy Dissipating devices more than 50% of energy is
absorbed by dampers.
Figure8 Energy curve
CONCLUSION
The seismic response of the structure with and without
damper under severe earthquake ground motion is
investigated with the help of SAP 2000 by modelling a 3D, 5
storey RC building. Following interesting conclusions are
obtained from the results of the study.
1. The fluid viscous dampers are found to be very effective
to control the response of structures under severe base
excitation.
2. Lesser dampers at appropriatelocationcansignificantly
reduce structural response due to base excitation.
3. Bottom storey dampers undergoes more deformation
and produces higher damping force as compare to top
storey dampers.
4. Fluid dampers with velocity exponent less than unity
shows visco-elastic behaviour and is found to resist
more velocity shocks, absorbs significant energy as
compare to dampers with velocity exponent equal to
unity.
5. Energy dissipated by the dampers for the considered
earthquake is up to 50%
6. Top storey displacement reduction in the range of 30-
40%.
7. Time history response of bending moment and shear
force is found to be reduced in the range of 25-40%.
REFERENCE
[1] Garcia, D. L., and Soong, T. T. (2002). “Efficiency of
Simple Approach to Damper allocation in MDOF
Structures”, Journal of Structural Control, 9, 19-30.
[2] Leu, L. J, and Chang, J. T. (2011). “Optimum Allocation
of Non-Linear ViscousDampersForThreeDimensional
Building Structures”, The twelfth East Asia-Pacific

Conference on Structural Engineering andConstruction,
Taipei, Taiwan.
[3] Patel, C. C., and Jangid R. S. (2009).“Seismicresponseof
dynamically similar adjacent structures with viscous
dampers”, The IES Journal Part A: Civil & Structural
Engineering. 3(1), 1-13.
[4] Patel, C. C., and Jangid, R. S. (2010)“Seismicresponseof
adjacent buildings connected with Maxwell damper”,
Asian Journal of Civil Engineering (Building and
Housing), 11(5), 585-603.
[5] Ras, A., and Boumechra, N. (2014). “Seismic energy
dissipation study of linear fluid viscous dampers in
steel structure design”, AlexandriaEngineeringJournal,
55(3), 2821-2832.

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