This paper presents a numerical study on the seismic response of pile-supported wharves equipped with metallic yielding dampers. Using 20 ground acceleration records, the contribution of the yielding damper is examined, and its main parameters are optimized through a parametric study. In the current study, considering coupling effects of different parameters, a new optimization procedure is proposed. The obtained results indicate that the stability condition of the retaining wall (quay wall) behind the wharf, period of the soil-wharf system, and also maximum allowable ductility ratio of the damper are the key factors affecting the optimum damper parameters. A simplified design guideline is proposed for either the design or the retrofit purposes followed by a numerical assessment to evaluate the contribution of the proposed damper on the seismic behavior of a typical pile-supported wharf. The obtained results show that yielding dampers, through their nonlinear behavior, can dissipate a large portion of seismic input energy and mitigate piles damages which have been observed in earlier earthquake events. 1. Introduction During an earthquake event liquefaction of saturated loose sandy soils and excessive piles drifts make the most common causes of damages to pile-supported wharves. Therefore, in absence of liquefaction conditions, pile drift can be considered as a suitable indicator in order to evaluate performance of wharves under seismic events. Some techniques, which rely on stiffness increasing, such as inclined piles, have been investigated in earlier studies by Gerolymos et al. [1] and Poulos [2], as a method to reduce lateral displacements of pile-supported wharves. Inclined piles have two main drawbacks, high construction costs and punching failures in their connections. As reported by Oyenuga et al. [3], however, the punching failure problem can be moderated using a new design approach for pile-deck connections. Lehman et al. [4] have also improved performance of pile-wharf connections. In another study a novel stone column has been proposed by Mageau and Chin [5] to improve seismic behavior of wharves. Using passive control techniques, this study tried to improve the seismic behavior of pile-supported wharves. Nowadays passive control methods have gained more attention in order to mitigate natural or man-made structural vibrations. Some of these passive techniques have been briefly described by Soong and Dargush [6]. Earlier studies on passive control techniques have been commonly restricted to long period structures, such as tall buildings,
References
[1]
N. Gerolymos, A. Giannakou, I. Anastasopoulos, and G. Gazetas, “Evidence of beneficial role of inclined piles: observations and summary of numerical analyses,” Bulletin of Earthquake Engineering, vol. 6, no. 4, pp. 705–722, 2008.
[2]
H. G. Poulos, “Raked piles—virtues and drawbacks,” Journal of Geotechnical and Geoenvironmental Engineering, vol. 132, no. 6, pp. 795–803, 2006.
[3]
D. Oyenuga, E. Abrahamson, A. Krimotat, A. Kozak, T. Labasco, and F. Lobedan, “A study of the pile-wharf deck connection at the Port of Oakland,” in Ports 2001: American’s Ports-Gateways to the Global Economy, 2004.
[4]
D. E. Lehman, E. Brackmann, A. Jellin, and C. W. Roeder, “Seismic performance of pile-wharf connections,” in Proceedings of the ASCE Technical Council on Lifeline Earthquake Engineering Conference (TCLEE '09), p. 84, Oakland, Calif, USA, July 2009.
[5]
D. Mageau and K. Chin, “Effectiveness of stone columns on slope deformations beneath wharves,” in Proceedings of the ASCE Technical Council on Lifeline Earthquake Engineering Conference (TCLEE '09), p. 94, Oakland, Calif, USA, July 2009.
[6]
T. T. Soong and G. Dargush, Passive Energy Dissipation Systems in Structural Engineering, Wiley, Chichester, UK, 1997.
[7]
C. Xia and R. D. Hanson, “Influence of ADAS element parameters on building seismic response,” Journal of Structural Engineering, vol. 118, no. 7, pp. 1903–1918, 1992.
[8]
D. Foti, L. Bozzo, and F. Lopez-Almansa, “Numerical efficiency assessment of energy dissipaters for seismic protection of buildings,” Earthquake Engineering and Structural Dynamics, vol. 27, pp. 543–556, 1998.
[9]
L. M. Moreschi and M. P. Singh, “Design of yielding metallic and friction dampers for optimal seismic performance,” Earthquake Engineering and Structural Dynamics, vol. 32, no. 8, pp. 1291–1311, 2003.
[10]
F. C. Ponzo, A. di Cesare, D. Nigro et al., “JET-PACS project: dynamic experimental tests and numerical results obtained for a steel frame equipped with hysteretic damped chevron braces,” Journal of Earthquake Engineering, vol. 16, pp. 662–685, 2012.
[11]
I. Towhata, M. J. Alam, T. Honda, and S. Tamate, “Model tests on behaviour of gravity-type quay walls subjected to strong shaking,” Bulletin of the New Zealand Society for Earthquake Engineering, vol. 42, no. 1, pp. 47–56, 2009.
[12]
A. Sadrekarimi, A. Ghalandarzadeh, and J. Sadrekarimi, “Static and dynamic behavior of hunchbacked gravity quay walls,” Soil Dynamics and Earthquake Engineering, vol. 28, no. 2, pp. 99–117, 2008.
[13]
OCDI, Technical Standards and Commentaries for Port and Harbor Facilities in Japan, The Overseas Coastal Area Development Institute of Japan, Tokyo, Japan, 2002.
S. Mazzoni, F. McKenna, M. H. Scott, and G. L. Fenves, The OpenSees Command Language Manual: Version 1.7.3, Pacific Earthquake Engineering Center, University of California, Berkeley, Calif, USA, 2006.
[16]
S. A. Mousavi, K. Bargi, and S. M. Zahrai, “Optimum parameters of tuned liquid column-gas damper for mitigation of seismic-induced vibrations of offshore jacket platforms,” Structural Control and Health Monitoring, vol. 20, no. 3, pp. 422–444, 2013.
[17]
Matlab, User Guide, Curve Fitting Toolbox, MathWorks Inc., Version 7.6.0, 2008.
[18]
Applied Technology Council (ATC), “Seismic evaluation and retrofit of concrete buildings,” Tech. Rep. ATC 40, Applied Technology Council, Redwood City, Calif, USA, 1996.
[19]
ASCE, Prestandard and Commentary for the Seismic Rehabilitation of Buildings (FEMA356), Federal Emergency Management Agency, Washington, DC, USA, 2000.
[20]
M. Tehranizadeh, “Passive energy dissipation device for typical steel frame building in Iran,” Engineering Structures, vol. 23, no. 6, pp. 643–655, 2001.
[21]
S. L. Kramer, Geotechnical Earthquake Engineering, Prentice Hall, Englewood Cliffs, NJ, USA, 1996.
[22]
R. W. Boulanger, C. J. Curras, B. L. Kutter, D. W. Wilson, and A. Abghari, “Seismic soil-pile-structure interaction experiments and analyses,” Journal of Geotechnical and Geoenvironmental Engineering, vol. 125, no. 9, pp. 750–759, 1999.
[23]
F. Castelli and M. Maugeri, “Simplified approach for the seismic response of a pile foundation,” Journal of Geotechnical and Geoenvironmental Engineering, vol. 135, no. 10, pp. 1440–1451, 2009.
[24]
J. P. Bardet, K. Ichii, and C. H. Lin, A Computer Program for Equivalent-Linear Earthquake Site Response Analyses, Department of Civil Engineering, University of Southern California, 2000.
[25]
A. Takahashi and J. Takemura, “Liquefaction-induced large displacement of pile-supported wharf,” Soil Dynamics and Earthquake Engineering, vol. 25, no. 11, pp. 811–825, 2005.
