Seismic Isolators in Pile-Supported Wharves

The main goal of this work is to incorporate seismic isolation in wharves and to determine advantages and disadvantages of the implementation of this technology from the technical and economical point of view. The main problems in the traditional design of wharves have been identified as soil-pile interaction and torsional eccentricity due to the asymmetry in the distribution of rigidity of the structure. Fifty-two seismic isolators have been incorporated in the most rigid piles of a typical wharf section and compared with the conventional structure. The soil-structure interaction has been modeled with P-Y curves from real scale test of piles on sloping ground conditions and geotechnical studies that consider the effect of sloping ground condition over the piles. By means of seismic isolators and flexibility of the longest piles of the wharf, a hybrid structure able to minimize the torsional eccentricity and to achieve a fundamental period of 3 seconds has been configured. Through the mentioned structure, the X and Y seismic coefficients have been reduced by 50% and 56% respectively, relative to the conventional wharf, allowing significant savings in the wharf elements. The cost estimation outcome has shown the isolated wharf piles are US$0.53 million lower than the traditional wharf, the isolated wharf platform is 0.81MUSD lower than the conventional wharf, and the isolation system (52 rubber isolators) cost is 0.29MUSD. In general, the direct cost of the seismic isolated wharf is 16% less than the cost of a traditional wharf while allowing for enhanced structural performance with insignificant damage during a severe seismic event. In addition to the described study, a representative project will be presented as the main motivation of this study. Coronel Port (Chile) is one of the first isolated ports in the world. The port was the only port in Chile that continued the operation after the massive earthquake of February 27th of 2010. Design and construction details and also the performance of the port for the last earthquake will be presented.