Optimal performance comparison of tall buildings with damped outrigger system by viscous and viscoelastic Kelvin-Voigt models under lateral vibration

Document Type : Original Article

Authors

1 Department of Civil Engineering, Faculty of Engineering, Imam Khomeini International university, Qazvin, Iran

2 Department of civil engineering, faculty of engineering, Imam Khomeini international university, Qazvin, Iran

3 Department of Civil Engineering, Faculty of engineering, Imam Khomeini International University, Qazvin, Iran

Abstract

Using central core system with peripheral columns and outrigger and employing the energy dissipation devices, such as viscous damper, is one of the structure lateral displacement mitigation’s methods. The central core system with the damped outrigger under seismic loads can be assessed by transverse vibration of a cantilever beam subjected to a concentrated moment due to spring-damper system. In this paper, two models are proposed for damped outrigger. After obtaining differential equation of vibration of a beam interacted with damped outrigger modeled as viscous and viscoelastic, and eigen value analysis, characteristic equations are derived. Complex frequencies and mode shapes are obtained with respect to non-dimensional parameters such as damping ratio and outrigger location and results are presented as modal damping ratio surfaces versus damping ratio and outrigger location and so optimal of these parameters for each mode are attained. The optimal locations of outrigger at first mode are 0.47 and 0.5 of the building height for viscous and viscoelastic models, respectively. In second mode, this value is 0.8 for both models. Analyzing a finite element model of a 40-story building and comparing frequency responses of the optimal and non-optimized models and the undamped models including the traditional outrigger and traditional core system without outrigger, validity of the proposed method is verified. The maximum of roof displacement in viscous and viscoelastic models are respectively about 16.4 cm and 1.1 cm, while it exceeds than the criteria of 1/400 of building’s height in the undamped models. In spite of greater modal damping ratio of viscous model, performance of the viscoelastic model is better. This is an indication of unrealistic viscosity model.

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[1]          Smith, B. S., & Salim, I. (1981). Parameter study of outrigger-braced tall building structures. Journal of the Structural Division, 107(10), 2001-2014.
[2]          Smith, R. J., & Willford, M. R. (2007). The damped outrigger concept for tall buildings. The Structural Design of Tall and Special Buildings, 16(4), 501-517.
[3]          Moudarres, F. R. (1984). Outrigger-braced coupled shear walls. Journal of Structural Engineering, 110(12), 2876-2890.
[4]          O'Neill, J. C. (2006). Application of damping in high-rise buildings (Doctoral dissertation, Massachusetts Institute of Technology).
[5]          Banerjee, J. R., & Williams, F. W. (1985). Exact Bernoulli–Euler dynamic stiffness matrix for a range of tapered beams. International Journal for Numerical Methods in Engineering, 21(12), 2289-2302.
[6]          Richards, T. H., & Leung, Y. T. (1977). An accurate method in structural vibration analysis. Journal of Sound Vibration, 55, 363-376.
[7]          Singh, R., Lyons, W. M., & Prater Jr, G. (1989). Complex eigensolution for longitudinally vibrating bars with a viscously damped boundary. Journal of sound and vibration, 133(2), 364-367.
[8]          Oliveto, G., Santini, A., & Tripodi, E. (1997). Complex modal analysis of a flexural vibrating beam with viscous end conditions. Journal of Sound and Vibration, 200(3), 327-345.
[9]          Gürgöze, M., & Erol, H. (2006). Dynamic response of a viscously damped cantilever with a viscous end condition. Journal of Sound and Vibration, 298(1-2), 132-153.
[10]        Chen, Y., McFarland, D. M., Spencer Jr, B. F., & Bergman, L. A. (2016). A beam with arbitrarily placed lateral dampers: Evolution of complex modes with damping. Journal of Vibration and Control, 1077546316641592.
[11]        Fang, C. J., Tan, P., Chang, C. M., & Zhou, F. L. (2015). A general solution for performance evaluation of a tall building with multiple damped and undamped outriggers. The Structural Design of Tall and Special Buildings, 24(12), 797-820.
[12]        Taranath, B. S. (1975). Optimum belt truss location for high-rise structures. Structural Engineer, 53(8), 18-21.
[13]        McNabb, J. W., & Muvdi, B. B. (1975). Drift reduction factors for belted high-rise structures. ENGINEERING JOURNAL-AMERICAN INSTITUTE OF STEEL CONSTRUCTION INC, 12(3), 88-91.
[14]        Hamidi, H., Pakdaman, J., Jahani, E., & Rajabnejad, H. (2017). The Assessment and Comparison of Tall Buildings with Outrigger and Belt Truss Systems Using Fragility Curves. Journal of Structural and Construction Engineering (JSCE), doi: 10.22065/jsce.2017.71179.1026.
[15]        Li, C. K. (2007). A review on the products of distributions. In Mathematical methods in engineering (pp. 71-96). Springer, Dordrecht.
[16]        Chen, Y., McFarland, D. M., Wang, Z., Spencer Jr, B. F., & Bergman, L. A. (2010). Analysis of tall buildings with damped outriggers. Journal of Structural Engineering, 136(11), 1435-1443.
[17]        Pacheco, B. M., & Fujino, Y. (1989). Perturbation technique to approximate the effect of damping nonproportionality in modal dynamic analysis. Doboku Gakkai Ronbunshu, 1989(404), 191-200.
[18]        Tan, P., Fang, C. J., Chang, C. M., Spencer, B. F., & Zhou, F. L. (2015). Dynamic characteristics of novel energy dissipation systems with damped outriggers. Engineering Structures, 98, 128-140.