Evaluation of the Tsunamic Vulnerability of an Existing Structure in Metallic Framework by Combining of the Time History Method and Capacity Curves Analysis with Interpretation of the Results According to Risk UE

Abstract

The massive amount of human and material damages, caused by the tragic tsunami of 26 December 2004 to the Indian Ocean, has been an intense incentive for the scientists and the civil engineers to predict the behavior of existing structures under the influence of various solicitations generated by this sinister devastation. Harbor infrastructures, particularly logistics depots, chemical, thermal and nuclear power stations and also the various installations classified as highly sensitive, remain potential targets that are highly exposed to the risks of tsunamis, especially since they are mostly light structures made of metal and not designed or dimensioned to withstand this hazard. The present work consists in evaluating the tsunamic vulnerability of an existing metallic hangar at the Jorf Lasfar harbor in Morocco, located about few meters from the Atlantic Ocean, a site containing a significant industrial activity. We have, in a first step, modeled the structure, on the SAP 2000 software, in order to check its stability against the wind, in accordance with the Moroccan calculation regulation. Then, the forces generated by the waves were modeled with the experimental tests according to the topographic data of the studied area and taking into account the numerical simulation results. These ones gives the maximum height of the wave retained is that recorded by the dramatic tsunami perpetrated on 1 November 1755. This tsunami was assumed to be the most unfavorable and destroyer in the North Atlantic Ocean, including the Moroccan City of El Jadida, located less than 18 kms from Jorf Lasfar harbor, causing harm and massive damage at that time. In a second step, a capacity curve was established following an incremental and successive loading on each row of steel columns, forming the supporting structure of the metal frame, by progressive application of the tsunamic forces on the time history format. The height of the wave was increased by a step of 0.5 m until reaching the maximum height previously fixed. The nonlinearity was introduced to the model through the plastic hinges at the nodes. The capacity curve obtained, represents the base shear reaction force of the structure as a function of the maximum displacement, this allowed us to determine the point of performance and the global response of the structure. Finally, we have interpreted the fragility curves established according to Risk UE, and the determination of the vulnerability of the structure in order to suggest the possible scenarios that will have to be recommended according to the different modes of probable damage.