VIBRATION ANALYSIS OF NONLINEAR CONICAL SPRING BRACING SYSTEM
SUBJECTED TO SEISMIC LOAD
Amir ateh1, arzad Hejazi1, , Mohd Saleh aafar1, Azlan Bin Adnan
Department of Civil Engineering, aculty of Engineering, University Putra Malaysia,
Serdang, Selangor, Darul Ehsan, Malaysia. Email: farzad fhejazi.com
aculty of Civil Engineering, University Technology Malaysia, 1 1 , UTM Skudai, ohor, Malaysia.
1
ABSTRACT
n this study, an attempt has been made to assess the impact of proposed nonlinear conical spring bracing
( CSB) system on seismic response subjected to earth uake. The developed system includes of two telescopic
conical spring springs that operate in axial compression. Due to shape of spring, the proposed system can
performed as a nonlinear stiffness element that provide more lateral stability to structural frame. The action of
CSB does not control the low and moderate vibration due to earth uake but i t acts for severe vibration
whereas the frame displacement pass the allowable boundary. This inconstant performance avoids excessive
effects of conventional bracing system if they attached as retrofitting components to moment resistant steel
frame. by other words, due to the aforementioned characteristics of CSB system, the inherent ductility of steel
frame is not scarified and earth uake energy can be dissipate due to frame ductility, but, CSB system provided
more stability of structures and prevent large story drift. n this study, pushover and time history analyses has
been conducted to evaluate the seismic performance of introduced device. The results from pushover disclose a
considerable enhancement of structural capacity and ductility. Besides, the application on CSB device changed
the location of plastic hinge formation in structural elements. urthermore, time history results proved the
efficiency of CSB device on reducing the maximum displacement.
KEYWORDS
Dynamic analysis, earth uake records, pushover analysis, nonlinear conical spring bracing, plastic hinge
formation, ductility.
INTRODUCTION
ibration impacts due to dynamic loads such as earth uake, wind and etc., can induce an unnecessary structure
oscillations which may cause to catastrophic collapse. mprovement of structural performance subjected to
dynamic loads is the most important concern in structural engineers, experts and researchers. The
aforementioned enhancement shall consider the structural stability (safety) and economical design feasibility. t
means that, the appropriate design techni ue especially choice of vibration control device is the most imperative
issue to prevent the structure from any vibration induced failure. The prior earth uake design approach was
based on inherent ductility of structures to dissipate the imposed earth uake energy. This practise was
considered as the most feasible and safe design. But it may lead to unrealistic design and structural damage. A
lot of research has been focused on supplementary energy dissipation devices which are installed in structures.
hereas these devices don t belong to main structural system can be offered as external energy dissipation
system which can be easily substituted after severe excitation (Tsu T Soong and Dargush 1 ). ibration
control techni ues n can be categorized into three main types: active control ( ao 1 ), passive control and
semi active control. Passive control methods were introduced at the earliest stage, and were used commonly in
seismic design procedure due to the minimum maintenance cost. Table 1, briefly presents the seismic control
system which has been introduced in a few studies.
Active variable stiffness (A S), a system for structural control has absorbed numerous attentions and interests.
The desire effects and improvement of the structural performance in earth uake excitation of A S systems were
proven by previous studies(Takuji Kobori et al. 1
)( ang, u, and i 1 ) Such a s ystem has been
investigated experimentally with implementation in full-scale building in apan(T Kobori and Kamagata 1 ).
Most of available variable stiffness system are operated using external electrical controller which might cause
delay in system performance. These systems are highly depended on energy recourse and also need repetitive
maintenance. ariable stiffness bracing system is developed as retrofitting system for steel structures which
included of four leaf springs in series with wire rope cable which its totally fabricate without dependency to
) focused on the nonlinear
electrical supply ( ateh et al. 1 )(Hejazi, aafar, and ateh 1 ).(Dct
behavior of the spring that could be achieved by varying the mean spring diameter in axial direction. n Conical
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springs we have some advantages compared to cylindrical springs. n non-telescoping springs, the coils stack
one above the other during compression. Another advantage of the conical springs can have a higher sideways
stability, so they will better resist buckling. (Dct
).
Table 1 Seismic control systems
ibration Control System
Metallic yield damper(Tyler 1 )(Scholl 1 )(T T Soong and Spencer r
)
riction damper(Pall et al. 1 )
isco- elastic dampers(Crosby, Kelly, and Singh 1 )(Moliner, Museros, and
Mart nez-Rodrigo 1 )
Passive energy
isco-fluid damper (Arima et al. 1 )(Rama Raju, Ansu, and yer 1 )
dissipation
Tuned mass damper( ujino and Ab 1 )(Soto and Adeli 1 )
system
Tuned li uid damper(Tamura et al. 1 )( eorgakis 11)
Rubber bearing Base isolation system( aeim 1
)
riction Pendulum Bearings( ang, Chung, and iao 1 )(Mos ueda, hittaker, and
enves
)
Active Mass Damper Systems( amamoto et al.
1)
Active Tendon Systems(Bossens and Preumont
1)
Active
Active Brace Systems(Cheng, iang, and ou 1 )
Control
Active coupled building systems(Christenson et al.
)
System
Pulse eneration Systems(Cheng, iang, and ou 1 )
Distributed actuators( isco and Adeli 11)
Hybrid Mass Dampers(Saito, Shiba, and Tamura
1)
HybridControl
Hybrid Base- solation System( ang, Danielians, and iu 1 1)
System
Hybrid Damper-Actuator Bracing Control(Cheng and iang 1 )
Semi-active Tuned Mass Dampers(Hrovat, Barak, and Rabins 1 )
Semi-active Tuned i uid Dampers(Banerji et al.
)
Semi-active riction Dampers(Chen and Chen
)
Semi-active ibration Absorbers(T T Soong and Spencer r
)
Semi-active
Semi-active Stiffness Control Devices(Patten et al. 1 )
Control System
Electrorheological Dampers(Makris et al. 1 )
Magnetorheological(MR) dampers(He, Huang, and iu 1 )(Dyke et al. 1 )
Semi-active iscous luid Damper(Symans and Constantinou 1 )
Piezoelectric dampers(Preumont et al.
)
The new bracing system with onlinear Conical Spring system was developed as adaptive structural control
system to protect the building against severe vibration and ground movement. CSB system includes nonlinear
leaf springs which induce nonlinear and onlinear Conical Spring capacity at different frame displacement. The
onlinear Conical Spring system ( CSB) system does not scarify the energy dissipation characteristics and
ductility capability of moment resistance frame. or large vibration amplitudes, the bracing member and
nonlinear spring acting and restrain unacceptably large storey drift. So, the braced frames can display ductile
performance which is dissipating seismic energy.
DEVELOPMENT OF NCSB DEVICE
CSB device installation in frame is shown in igure 1. nce the frame subjected to dynamic force such as
earth uake excitations, it sways to left and right and CSB device intents to move to the right and left. Due to
dual action of CSB and compression resisting of conical spring, the induced force form vibration transfer to
the device by cables. Since the cable is buckling free element, the force can be easily transfer to the main device
in unlimited cycle. The action of CSB can be divided to two main phases include solid telescopic conical
spring and cable actions. or more explanation, whenever the device reaches to maximum deflection of conical
spring, the cable stiffness adds to system stiffness since it works as braces which fixed at both ends.The D
schematic model is presented in igure .
The details of CSB elements layout is describe in igure . The CSB device comprises of a nonlinear solid
conical spring bracing attached to a cable to counter the dynamism of the force resulted from the vibration on
the structure of a building The nonlinear conical spring bracing device further comprising, of a rectangular
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frame having an exterior clamper (label 1) at each vertical side of the rectangular frame. A telescopic conical
spring (label ) attached at each end of the rectangular frame at the exterior clamper (lable1). urthermore a
steel rail (label ) fixed at middle of the rectangular frame. An interior clamper ( abel ) attached to each
telescopic conical spring (label ), the cylindrical core (label ) is slidable along the steel rail (label ) and a
steel rod (label ) passes through each end of the rectangular frame and the interior clamper ( ) and ended at the
middle of the cylindrical core (label ).
igure 1 CSB nstallation and action in frame
igure
-D schematic view of CSB
1
3
4
5
2
igure 1 CSB elements layout
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DYNAMIC EVALUATION OF NCSB IN DEVELOPED ARCS3D
The mathematical model of CSB has been implemented in developed web based software called as ARCS D
which is abbreviated of Analysis of Reinforced Concrete Structure- D. The push over and time history analysis
of reinforced concrete (RC) structures furnished by CSB device performed for -story building. More over the
results compared with bare frame and efficiency of CSB application has been discussed. The compressive
concrete strength grade for both pushover and time history analyses are considered as
MPa. The columns and
beams are modeled with same geometry sizes of
X
mm as shown in igure . The diameter of
reinforcement bars and concrete cover to steel bars are assumed
mm and
mm respectively in all the cases.
n addition to, the story height and bay width for all models are and m correspondingly.
mm
mm
igure beams and columns sections
RESULTS AND DISCUSSIONS
Pushover Analysis
Pushover analysis is conducted for frame e uipped with and without CSB device as presented in igure . The
CSB spring wire s diameter and spring s length are e ualed to and 1 mm respectively. The biggest and
smallest diameters of conical spring considered as
and 1 mm. urthermore, the diameter of wire rope
cable e uals to 1 mm with high strength steel material. Results from pushover analysis for both models are
reported in igure . As can be observed, the implementation of CSB device caused to increase the pushover
capacity by
and reached to
K and also the ductility characteristic of frame furnished by CSB
enhanced. n addition to, the locations of plastic hinge formation in structures are monitored and presented in
igure . n the bare frame the plastic hinge initially formed at base nodes at columns then extended to upper
columns. But, once the CSB applied, the locations of plastic hinges altered and moved into the device around
1 .it means CSB implementation in frame not only increase the structure capacity and ductility but also
reduce the plastic hinge formation in structural components and shift them in CSB device.
igure
Pushover models in ARCS D
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500000
bare frame
Force(N)
400000
300000
200000
100000
0
0
igure
(a)
igure
50 Displacement(mm)
100
150
200
250
Push over curve for frame with and without CSB system
(b)
ocation of plastic hinge formation at (a) bare and (b) CSB frames
Time History Analysis
Ground Acceleration(g)
Time history analysis for bare and CSB subjected to El-Centro orth-South (1 ) as shown in igure , is
conducted with developed finite element program. The -story models are analyzed with and without CSB
system. All beams are subjected to the e ual Kn m distributed loads. Moreover, 1 K point loads are
applied at all columns as illustrated in igure . The results reported in terms of time history of top node
displacement. igure 1 shows the displacement change verse time of considered top nodes in both models. As
can be observed, application of CSB device in frame caused to reduce the maximum absolute displacement
about
.
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
0
10
20
30
Time(Sec)
igure El-Centro Earth uake (1
40
50
) acceleration orth South record
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60
igure
Pushover models in ARCS D
Displacement (mm)
25
15
Bare frame
5
-5
-15
-25
Displacement(mm)
0
10
20
30
Time(sec)
(a)Bare frame
20
15
10
5
0
-5
-10
-15
-20
40
50
60
NCSB frame
0
10
20
30
40
50
Time(sec)
(b) CSB frame
igure 1 displacement response histories under El-Centro earth uakes
60
CONCLUSION
This study introduced a rapid retrofitting techni ue for frame structures. onlinear conical bracing system
comprised of two telescopic solid conical springs which are attached to wire rope cables. CSB device can be
applied as a new rapid retrofitting practice due to simplicity of CSB fabrication and installation process in high
ductility frame. Moreover it can be used as supplementary lateral resisting element in ne w framed building.
Push over and time history analyses of story RC frame with and without CSB device has been performed.
The results from push over analysis reveal the efficiency of CSB device in structure. ot only the capacity and
ductility characteristics of frame enhanced but also, the location of plastic hinge formations altered from main
structural elements and shifted in CSB device as supplementary energy dissipation system. urthermore, time
history analysis reports a considerable reduction of maximum displacement value.
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or future study, finite element simulation is extremely essential to assess the CSB ductility performance
under monotonic displacement. Besides, the experimental dynamic test must be conducted to evaluate the
seismic response of aforesaid method in reality by use of pseudo dynamic actuator or shaking table.
ACKNOWLEDGEMENT
This work received financial support from the Ministry of Science, Technology, and nnovation of Malaysia
under Research Project o.
. This support is gratefully acknowledged. The CSB system is under
filling patent grant at Malaysia intellectual property organizations (My P ).
CONFLICT OF INTERESTS
The authors declare that there is no conflict of interests regarding the publication of this paper.
REFERENCES
Arima, ., Miyazaki, M., Tanaka, H.,
amazaki, . (1 ). A study on buildings with large damping using
viscous damping walls . n Proceedings of the 9th World Conference on Earthquake Engineering ( ol.
1).
Banerji, P., Murudi, M., Shah, A. H., Popplewell, . (
). Tuned li uid dampers for controlling
earth uake response of structures . Earthquake Engineering & Structural Dynamics, 29( ),
.
Bossens, ., Preumont, A. ( 1). Active tendon control of cable stayed bridges: a large scale
demonstration . Earthquake Engineering & Structural Dynamics, 30( ), 1
.
Chen, C., Chen, . (
). Shake table tests of a uarter scale three storey building model with piezoelectric
friction dampers . Structural Control and Health Monitoring, 11( ),
.
Cheng, . .,
iang, H. (1 ). Hybrid control of seismic structures with optimal placement of control
devices . Journal of Aerospace Engineering, 11( ),
.
Cheng, . ., iang, H.,
ou, K. ( 1 ). Smart structures: innovative systems for seismic response control.
CRC Press.
Christenson, R. E., Spencer r, B. ., Hori, ., Seto, K. (
). Coupled building control using acceleration
feedback . Computer-Aided Civil and Infrastructure Engineering, 18(1), 1 .
Crosby, P., Kelly, ., Singh, . P. (1 ). Utilizing visco-elastic dampers in the seismic retrofit of a thirteen
story steel framed building . n Structures Congress XII (pp. 1
1 1). ASCE.
Dct, B. (
). onlinear dynamic behavior of a conical spring with top mass .
Dyke, S. ., Spencer r, B. ., Sain, M. K., Carlson, . D. (1 ). Modeling and control of
magnetorheological dampers for seismic response reduction . Smart Materials and Structures, 5( ),
.
ateh, A., Hejazi, ., aafar, M. S., bin Adnan, A. ( 1 ). Dynamic Analysis of ariable Stiffness Bracing
System in Structure . n Applied Mechanics and Materials ( ol.
, pp.
). Trans Tech Publ.
isco, . R., Adeli, H. ( 11). Smart structures: part
active and semi-active control . Scientia Iranica,
18( ),
.
ujino, ., Ab , M. (1 ). Design formulas for tuned mass dampers based on a perturbation techni ue .
Earthquake Engineering & Structural Dynamics, 22(1 ),
.
eorgakis, C. T. ( 11, uly ). Tuned li uid damper . oogle Patents.
He, . M., Huang, .,
iu, C. ( 1 ). ield and rheological behaviors of magnetorheological fluids .
Advanced Materials Research, 97,
.
Hejazi, ., aafar, M. S.,
ateh, A. ( 1 ). A variable stiffness bracing device .
Hrovat, D., Barak, P., Rabins, M. (1 ). Semi-active versus passive or active tuned mass dampers for
structural control . Journal of Engineering Mechanics, 109( ), 1
.
Kobori, T., Kamagata, S. (1 ). Dynamic intelligent buildings: Active seismic response control .
Intelligent Structures, 2,
.
Kobori, T., Takahashi, M., asu, T., iwa, .,
gasawara, K. (1 ). Seismic response controlled structure
with active variable stiffness system . Earthquake Engineering & Structural Dynamics, 22(11),
1.
Makris, ., Hill, D., Burton, S.,
ordan, M. (1 ). Electrorheological fluid damper for seismic protection of
structures . n Smart Structures & Materials’ 95 (pp. 1 1 ). nternational Society for ptics and
Photonics.
Moliner, E., Museros, P., Mart nez-Rodrigo, M. D. ( 1 ). Retrofit of existing railway bridges of short to
medium spans for high-speed traffic using viscoelastic dampers . Engineering Structures, 40, 1
.
Mos ueda, ., hittaker, A. S.,
enves, . . (
). Characterization and modeling of friction pendulum
bearings subjected to multiple components of excitation . Journal of Structural Engineering, 130( ),
.
1276
aeim, . (1
). Design of seismic isolated structures: from theory to practice”. ohn iley Sons.
Pall, A., ezina, S., Proulx, P., Pall, R. (1 ). riction-dampers for seismic control of Canadian space
agency head uarters . Earthquake Spectra, 9( ),
.
Patten, . ., Mo, C., Kuehn, .,
ee, . (1
). A primer on design of semiactive vibration absorbers
(SA A) . Journal of Engineering Mechanics, 124(1), 1
.
Preumont, A., De Marneffe, B., Deraemaeker, A., Bossens, . (
). The damping of a truss structure with
a piezoelectric transducer . Computers & Structures, 86( ),
.
Rama Raju, K., Ansu, M.,
yer, . R. ( 1 ). A methodology of design for seismic performance
enhancement of buildings using viscous fluid dampers . Structural Control and Health Monitoring, 21( ),
.
Saito, T., Shiba, K., Tamura, K. ( 1). ibration control characteristics of a hybrid mass damper system
installed in tall buildings . Earthquake Engineering & Structural Dynamics, 30(11), 1
1 .
Scholl, R. E. (1 , March ). Added damping and stiffness elements . oogle Patents.
Soong, T. T., Dargush, . . (1 ). Passive energy dissipation systems in structural engineering .
Soong, T. T., Spencer r, B. . (
). Supplemental energy dissipation: state-of-the-art and state-of-thepractice . Engineering Structures, 24( ),
.
Soto, M. ., Adeli, H. ( 1 ). Tuned Mass Dampers . Archives of Computational Methods in Engineering,
20( ), 1
1.
Symans, M. D., Constantinou, M. C. (1 ). Development and experimental study of semi-active fluid
damping devices for seismic protection of structures .
Tamura, ., ujii, K., htsuki, T., akahara, T., Kohsaka, R. (1 ). Effectiveness of tuned li uid dampers
under wind excitation . Engineering Structures, 17( ),
1.
Tyler, R. . (1 ). urther notes on a steel energy-absorbing element for braced frameworks . Bulletin of the
New Zealand National Society for Earthquake Engineering, 18( ),
.
ang, ., Chung, .,
iao, . (1 ). Seismic response analysis of bridges isolated with friction pendulum
bearings . Earthquake Engineering & Structural Dynamics, 27(1 ), 1
1 .
amamoto, M., Aizawa, S., Higashino, M., Toyama, K. ( 1). Practical applications of active mass
dampers with hydraulic actuator . Earthquake Engineering & Structural Dynamics, 30(11), 1
1 1 .
ang, . ., u, . .,
i, . (1 ). Control of seismic-excited buildings using active variable stiffness
systems . Engineering Structures, 18( ),
. doi:1 .1 1 1 1( ) 1 -1
ang, . ., Danielians, A.,
iu, S. C. (1 1). Aseismic hybrid control systems for building structures .
Journal of Engineering Mechanics, 117( ),
.
ao, . T. P. (1 ). Concept of structural control . Journal of the Structural Division, 98( ), 1
1 .
1277