Metaheuristic based optimization of tuned mass dampers on single degree of freedom structures subjected to near fault vibrations

Abstract

Near fault ground motions excitations have specific characteristics comparing to regular earthquake excitations. Near fault ground motions contain directivity pulses and flint steps in different directions and these excitations are the reason of more damages than regular excitations for structures. A successful method to reduce structural vibrations is the usage of tuned mass dampers. By using optimally tuned mass dampers, it will be possible to reduce vibrations resulting from earthquake excitations. In the present study, the optimization of tuned mass dampers are done for near fault excitations. During optimization, 6 different pulse like excitations are used. Three of these excitations are directivity pulses while the other ones are flint steps. The periods of excitations are 1.5s, 2.0s and 2.5s since near fault pulses have long period and big peak ground velocity around 200 m/s. The optimization objectives are related to maximum displacement of structure in time domain, the maximum stroke limitation of tuned mass damper and transfer function of the structure in frequency domain analyses. The iterative optimization process uses both time and frequency domain analyses of the structure. Three different metaheuristic algorithms are used in the methodology. These methods are harmony search algorithm, teaching learning based optimization and flower pollination algorithm which are inspired from musical performances, education process and reproduction of flowering plants, respectively. As the numerical investigation, three different single degree of freedom structures with periods 1.5s, 2.0s and 2.5s are investigated for optimum mass, period and damping ratio of a tuned mass damper positioned on the structure.

Keywords

• Metaheuristic algorithm,Near fault vibrations,Optimization,Tuned mass dampers

Kaynakça

1. [1]. Makris, N., (1997). Rigidity-Plasticity-Viscosity: Can Electrorheological Dampers Protect Base-Isolated Structures From Near-Source Ground Motions? Earthquake Engineering and Structural Dynamics, 26, 571-591.
2. [2]. Den Hartog, J. P., (1947). Mechanical Vibrations. McGraw-Hill, New York.
3. [3]. Warburton, G.B., (1982). Optimum absorber parameters for various combinations of response and excitation parameters. Earthquake Engineering and Structural Dynamics, 10, 381–401.
4. [4]. Sadek, F., Mohraz, B., Taylor, A.W., Chung, R.M., (1997). A Method of Estimating The Parameters of Tuned Mass Dampers for Seismic Applications. Earthquake Engineering and Structural Dynamics, 26, 617–635.
5. [5]. Bekdaş, G., Nigdeli, S.M., (2011). Estimating Optimum Parameters of Tuned Mass Dampers using Harmony Search. Engineering Structures, 33, 2716-2723.
6. [6]. Hadi, M.N.S., Arfiadi, Y., (1998). Optimum Design of Absorber for MDOF Structures. Journal of Structural Engineering-ASCE, 124, 1272–1280.
7. [7]. Bekdaş, G., & Nigdeli, S. M., (2017). Metaheuristic Based Optimization of Tuned Mass Dampers Under Earthquake Excitation by Considering Soil-structure Interaction. Soil Dynamics and Earthquake Engineering, 92, 443-461.
8. [8]. Bekdaş G, Nigdeli SM, Yang X-S, Metaheuristic Based Optimization for Tuned Mass Dampers Using Frequency Domain Responses. In: Harmony Search Algorithm. Advances in Intelligent Systems and Computing, vol 514, Del Ser J. (eds) Springer, pp. 271-279, 2017.

9. [9]. Geem, Z. W., Kim, J. H., & Loganathan, G. V. (2001). A new heuristic optimization algorithm: harmony search. Simulation, 76(2), 60-68.
10. [10]. Yang, X. S., (2012). Flower Pollination Algorithm for Global Optimization. International Conference on Unconventional Computing and Natural Computation (pp. 240-249), Springer Berlin Heidelberg.
11. [11]. Rao, R. V., Savsani, V. J., & Vakharia, D. P., (2011). Teaching–learning-Based Optimization: A Novel Method for Constrained Mechanical Design Optimization Problems. Computer-Aided Design, 43(3), 303-315.