Seismic Retrofitting the Steel Storage Tanks using Single Concave Friction Isolators under the Long Period Earthquakes

Document Type: Regular Paper


1 M.Sc. of Earthquake Engineering, Civil Engineering Department, Semnan Branch, Islamic Azad University, Semnan, Iran

2 Associate Professor, Seismic Geotechnical and High Performance Concrete Research Centre, Civil Engineering Department, Semnan Branch, Islamic Azad University, Semnan, Iran


Cylindrical liquid storage tanks are contemplated as vital structures in industrial complex whose nonlinear dynamic behavior is of crucial importance. Some of these structures around the world have demonstrated poor seismic behavior over the last few decades; consonantly a major improvement is required to reach their level of applicability. There are several methods and techniques for rehabilitation and reducing damages in these structures which among them the devices for passive control, particularly base isolators, are perceptible. Friction Pendulum System (FPS) is the most popular base isolation system which its period does not depend on the structural weight. In this research work, the efficiency of FPS is examined on decreasing the seismic responses of base isolated steel storage tanks as well as the impact effect of slider to the side restrainer. To this end, the whole mass of liquid storage tank is contemplated as three lumped masses known as convective mass, impulsive mass which is connected to tanks with corresponding spring, and rigid mass which is connected rigidly. By means of state space method the time history analysis is done applying 60 earthquake records to acquire dynamic responses under the various hazard levels i.e. SLE, DBE and MCE ground motions. The results show that the normalized base shear force in squat tank decreased 59%, 62% and 33% respectively under SLE, DBE and MCE ground motions. The reduction of normalized base shear force in slender tank is 53%, 49% and 35% under the aforementioned hazard levels. Examining the effect of side restrainer’s stiffness on the maximum responses exhibit that the impact effect must be considered particularly when the system is excited by MCE’s ground motions.


Main Subjects

[1] Cooper, T.W. and T.P. Wachholz. Optimizing post-earthquake lifeline system reliability. 1999. 5th US conference on lifeline earthquake engineering: ASCE.

[2] Housner, G.W., The dynamic behavior of water tanks. Bulletin of the seismological society of America, 1963. 53(2): p. 381-387.

[3] Rosenblueth, E. and N.M. Newmark, Fundamentals for Earthquake Engineering. 1971: Prentice Hall.

[4] Haroun, M.A., Vibration studies and tests of liquid storage tanks. Earthquake Engineering and Structural Dynamics, 1983. 11(2): p. 179-206.

[5] Chalhoub, M.S. and J.M. Kelly, Theoretical and experimental studies of cylindrical water tanks in base isolated structures. 1988: Earthquake Engineering Research Center, University of California at Berkeley.

[6] Zayas, V.A. and S.S. Low, Application of seismic isolation to industrial tanks. 1995: American Society of Mechanical Engineers, New York.

[7] Malhotra, P.K., New method for seismic isolation of liquid‐storage tanks. Earthquake engineering and structural dynamics, 1997. 26(8): p. 839-847.

[8] Malhotra, P.K., Method for seismic base isolation of liquid-storage tanks. Journal of Structural Engineering, 1997. 123(1): p. 113-116.

[9] Shrimali, M. and R. Jangid, A comparative study of performance of various isolation systems for liquid storage tanks. International Journal of Structural Stability and Dynamics, 2002. 2(04): p. 573-591.

[10] Shrimali, M. and R. Jangid, Non-linear seismic response of base-isolated liquid storage tanks to bi-directional excitation. Nuclear Engineering and design, 2002. 217(1): p. 1-20.

[11] Bagheri, S. and M. Farajian, The effects of input earthquake characteristics on the nonlinear dynamic behavior of FPS isolated liquid storage tanks. Journal of Vibration and Control, 2016: p. 1077546316655914.

[12] Abalı, E. and E. Uçkan, Parametric analysis of liquid storage tanks base isolated by curved surface sliding bearings. Soil Dynamics and Earthquake Engineering, 2010. 30(1): p. 21-31.

[13] Virella, J.C., L.A. Godoy, and L.E. Suárez, Dynamic buckling of anchored steel tanks subjected to horizontal earthquake excitation. Journal of Constructional Steel Research, 2006. 62(6): p. 521-531.

[14] Alembagheri, M. and H.E. Estekanchi, Nonlinear analysis of abovground anchored steel tanks using endurance time method. Asian Journal of Civil Engineering, 2011. 12(6): p. 731-750.

[15] Yong-Chul, K., et al., Seismic isolation analysis of FPS bearings in spatial lattice shell structures. Earthquake Engineering and Engineering Vibration, 2010. 9(1): p. 93-102.

16.     [16] Jia, G. and Z. Shi, A new seismic isolation system and its feasibility study. Earthquake Engineering and Engineering Vibration, 2010. 9(1): p. 75-82.

[17] Haroun, M.A., Vibration studies and tests of liquid storage tanks. Earthquake Engineering & Structural Dynamics, 1983. 11(2): p. 179-206.

[18] Mokha, A., et al., Experimental study of friction-pendulum isolation system. Journal of Structural Engineering, 1991. 117(4): p. 1201-1217.

[19] Kim, Y.-S. and C.-B. Yun, Seismic response characteristics of bridges using double concave friction pendulum bearings with tri-linear behavior. Engineering Structures, 2007. 29(11): p. 3082-3093.

[20] Fenz, D.M., Development, implementation and verification of dynamic analysis models for multi-spherical sliding bearings. 2008: ProQuest.

[21] Simulink, M. and M. Natick, The MathWorks. Inc., Natick, MA, 1993.

[22] Shrimali, M. and R. Jangid, Seismic response of liquid storage tanks isolated by sliding bearings. Engineering structures, 2002. 24(7): p. 909-921.

[23] Koketsu, K. and H. Miyake, A seismological overview of long-period ground motion. Journal of Seismology, 2008. 12(2): p. 133-143.

[24] Malekzadeh, M. and T. Taghikhany, Adaptive behavior of double concave friction pendulum bearing and its advantages over friction pendulum systems. Scientia Iranica. Transaction A, Civil Engineering, 2010. 17(2): p. 81.

[25] Mortezaei, A. and H.R. Ronagh, Effectiveness of modified pushover analysis procedure for the estimation of seismic demands of buildings subjected to near-fault ground motions having fling step. Nat. Hazards Earth Syst. Sci., 2013. 13(6): p. 1579-1593.

[26] Colombo, J.I., Almazán, J.L. Seismic reliability of legged wine storage tanks retrofitted by means of a seismic isolation device. Engineering Structures. 2017, 134:303-16.

[27] Hashemi, S., Aghashiri, M.H. Seismic responses of base-isolated flexible rectangular fluid containers under horizontal ground motion. Soil Dynamics and Earthquake Engineering. 2017, 100:159-68.