This study aims to develop seismic fragility curves for a typical PILESUPPORTED WHARF. Fragility curve is one of the popular tools in seismic performance evaluation of a structure. The software FLAC2D was used to simulate the seismic performance of the WHARF structure. Using eight time history records, occurred in past, as seismic loading, incremental dynamic analysis (IDA) was applied for seismic demand estimation. Based on the resulted seismic response matrix the analytical fragility curves were developed. As a prevailing tool, adopted fragility curves are useful for seismic risk assessment. They can also be used to optimize WHARF-retrofit methods.

This paper aims to tackle an important uncertainty which extremely affects seismic performance of WHARF structures in earthquake events. According to previous studies performed for structures on land, it is shown that structures on land are highly susceptible to unknown orientation of earthquakes called as the directional uncertainty. However, for marine structures, especially PILE SUPPORTED wharves, research efforts are rare to assess the effect of directional uncertainty of earthquakes on structural responses. Therefore, to show this effect on seismic performance of PILE SUPPORTED wharves, fragility analysis is performed based on methodology suggested by Pacific Earthquake Engineering Research Center (PEER) for the modeled PILE SUPPORTED WHARF located in Maah-shahr port as a case study. As the first phase of this methodology, nonlinear static pushover analyses are performed for randomly chosen incident angles in order to quantitatively measure damage states suggested by marine design code. After damage states are obtained, IDA analyses are conducted in the selected incident angles to obtain nonlinear structural responses which are supposed to be used for fragility analysis as inputs. Finally, once fragility curves have been developed according to the last phase of PEER methodology, the more vulnerable direction(s) of WHARF from those incident angles is represented.

One of the most important structures in the ports is the WHARF. The most common one is the PILESUPPORTED WHARF. This type of WHARF is consisted of a number of PILEs and one deck which placed on the PILEs. In addition to the conventional loads that this structure should withstand, in seismic areas, PILE-SUPPORTED WHARFs should have the necessary capacity and strength against seismic excitations. There are some approaches to increase the seismic capacity of the berth. One of these methods is to control the vibrations of the PILE-SUPPORTED WHARF against earthquake loads using a damper. In this research, for the first time, a new semi-active damper called the semi active liquid column gas damper (SALCGD), was used to reduce the response of PILE SUPPORTED WHARF under seismic loads. In the first step by applying different records of the earthquake, the most important parameter of this damper-the optimal opening ratio of the horizontal column-was obtained for this particular structure. In the following, the performances of this damper and its comparison with the tuned liquid column gas damper (TLCGD) were discussed. This study showed that the use of this semi-active damper (SALCGD) reduces the displacement of the PILE-SUPPORTED WHARF by 35% and reduces the acceleration of the structure by 50% on average. In contrast, the passive damper (TLCGD) reduces the displacement of about 20 percent and the acceleration of about 30 percent. Therefore, it was observed that the semi-activation of the damper (SALCGD) had a significant improvement in its performance in controlling the vibrations of PILE-SUPPORTED WHARF.