Hindawi Publishing Corporation Journal of Structures Volume 2013, Article ID 329130, 13 pages http://dx.doi.org/10.1155/2013/329130 Research Article Enhancing Seismic Capacity of Pile-Supported Wharves Using Yielding Dampers Seyed Amin Mousavi and Khosrow Bargi School of Civil Engineering, University of Tehran, P.O. Box 11365-4563, Tehran, Iran Correspondence should be addressed to Seyed Amin Mousavi; s.a.mousavi@ut.ac.ir Received 15 February 2013; Revised 5 May 2013; Accepted 13 May 2013 Academic Editor: Domenico Bruno Copyright © 2013 S. A. Mousavi and K. Bargi. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. his 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 efects of diferent parameters, a new optimization procedure is proposed. he 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 afecting the optimum damper parameters. A simpliied design guideline is proposed for either the design or the retroit purposes followed by a numerical assessment to evaluate the contribution of the proposed damper on the seismic behavior of a typical pile-supported wharf. he 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 drits make the most common causes of damages to pile-supported wharves. herefore, in absence of liquefaction conditions, pile drit can be consid- ered as a suitable indicator in order to evaluate performance of wharves under seismic events. Some techniques, which rely on stifness 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 struc- tural vibrations. Some of these passive techniques have been briely described by Soong and Dargush [6]. Earlier studies on passive control techniques have been commonly restricted to long period structures, such as tall buildings, long-span bridges, and ofshore jacket platforms, to the authors’ knowledge, passive energy dissipation devices have not been investigated earlier for wharves. Among various passive dampers, metallic yielding damper seems to be more appropriate as yielding dampers are easy to manufacture and need no speciic maintenance. To date, many studies have been devoted to yielding dampers [7–10]. However, they have mainly focused on building structures in which dampers were in conjunction with chevron braces. Nowadays, with increasing ship sizes, berth deepening seems to be inevitable and consequently a new generation of pile-supported wharves would have relatively larger periods. Accordingly, the focus of this study is mainly on lexible wharves. As depicted in Figure 1, stability conditions of the retaining wall would dictate the maximum allowable yielding