Seismic Vulnerability Assessment of Retrofitted Steel Structures with Fractional Viscoelastic Dampers Considering Uncertainty Variables

Document Type : Original Article

Authors

1 M.S. Graduated

2 Civil Engineering, Assistant Professor, Isfahan University of Technology, Isfahan, Iran.

Abstract

Using viscoelastic (VE) dampers is one of the most effective tools for seismic retrofitting of steel structures. The results of many experimental studies demonstrated that using fractional derivative terms for modelling viscoelastic dampers offers an acceptable level of accuracy. Unlike viscous dampers the damping force is not linearly dependent to velocity and it is also highly affected by excitation frequency and ambient temperature. For this reason, solving the dynamic equation and calculating the seismic response of the structures equipped with VE dampers have many complexities. In this paper, the responses of a viscoelastically damped structure are calculated and the seismic performance of the building is evaluated while considering the effects ambient temperature as well as the inherent uncertainties related to ground motion excitation.
The proposed relationships were used to calculate the structural responses and assess the seismic performance of a 5-story steel structure retrofitted with fractional viscoelastic dampers. The maximum relative displacement of the controlled structural at the operation, design, and maximum considered expected hazard levels were compared to those of the initial structure (without damper). Furthermore, fragility curves were used to compare responses and exceedance probabilities of performance limit states. The results show great improvement in structural seismic performance related to the reduction of both structural responses and exceedance probabilities of limit states. The effect of temperature changes in results has been also demonstrated.

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[1] Dusicka, P. Lewis, G.R. (2010). Replaceable shear and flexural links for the linked column frame system. Master of Science thesis, Civil and environmental engineering, Portland State University.
[2] Dusicka, P. Iwai, R. (2007). Development of linked column frame system for seismic lateral loads, Structural engineering research frontiers, structures congress, ASCE, 1-13.
[3] Stephens, M. (2011). Numerical and Experimental Analysis of Composite Sandwich Links for the LCF A thesis Master of Science in Civil and Environmental Engineering, Portland State University
[4] Malakoutian, M. (2012). Seismic response evaluation of the linked column frame system. Doctoral dissertation, University of Washington.
[5] Lopes, A. Dusicka, P..Berman, J. (2015). Lateral Stiffness Approximation of Linked Column Steel Frame System.ASCE Structures Congress
[6] Pires Lopes, A. (2016). Seismic behavior and design of the linked column steel frame system for rapid return to occupancy. Doctoral dissertation, Civil and Environmental Engineering, Portland State University
[7] Shoeibi, Sh. (2019). Simplified force-based seismic design procedure for linked column frame system, Soil Dynamics and Earthquake Engineering, 87-101.
[8] Gholhaki,M. Foroozan,F. Rezayfar,O. (2019). A Study on the Performance-Based Seismic Design of Linked Column Frame (LCF) System Subjected to Near and Far-Field Earthquakes. Journal of Structural and Construction Engineering.
[9] ANSI, A. (2010). AISC 341-10. Seismic provisions for structural steel buildings. Chicago (IL): American Institute of Steel Construction.
[10] Mazzoni, S. McKenna, F. Scott, and MH. Fenves, GL. (2006). Open system for engineering simulation user-command-language manual, version 2.0, Pacific Earthquake Engineering Research Center. University of California, Berkeley.
[11] FEMA P695. (2009). Quantification of building seismic performance factors, Applied Technology Council for the Federal Emergency Management Agency.
[12] Shoeibi, Sh. Kafi, MA and Gholhaki, M. (2017). New Performance-based seismic design method for structures with structural fuse system. Engineering Structures, 745–760.
[13] Shoeibi, Sh. (2017). Seismic design method and performance assessment of linked column frame system (LCF), Doctoral dissertation, University of Semnan.
[14] American Institute of Steel Construction. (2005). Seismic provisions for structural steel buildings. American Institute of Steel Construction.
[15] ASCE 7-10. (2010). Minimum design loads for buildings and other structures. American Society of Civil Engineers.
[16] FEMA-350C. (2000). Recommended seismic design criteria for new steel moment-frame buildings. Report No. 350, SAC Joint Venture for the Federal Emergency Management Agency, Washington, D.C.
[17] Shome, N. Cornell, CA. (1999). Probability seismic demand analysis of nonlinear structures. Ph.D, dissertation. Stanford University