FEM Dynamic Analysis Of Large-size LNG Tanks Considering The Pile-Soil-Structure Interaction

With the application of LNG, the size of LNG storage tanks have become biggerand bigger. At this stage, the research results of the LNG storage tank focused on thestatic analysis, construction techniques, and so on. Compared to these, the dynamicanalysis of large LNG tanks is less. In order to get a more accurate model, and haveour own design earlier, this dissertation has done a more in-depth study. Thisdissertation takes the actual project as the background, and takes FEM program"ANSYS version 11.0"as the main analytical tool. The reliable analysis result for thedesign of LNG tanks has been obtained by conducting through research theoretically.The main parts of this dissertation are describes as follows:(1)This dissertation divides the pile-soil function area into three parts: the pureland area, the pile soil area and the area far away. Because the interaction between soiland pile is complex, the pile-soil region is simulated to a equivalent compositematerial model.(2)Different units are choose for different models. When the model consideringthe pile-soil-structure Interaction is simulated, the tank is regarded as a beam-columnsystem. In that model, the pile-soil model is a detailed part.(3)The model considering the pile - soil - structure Interaction and the model notconsidering the pile - soil - structure Interaction are both simulated. A number of keypoints are selected according to different heights and different angles. Under theaction of three seismic waves, the seismic responds of the two models are calculated,and the results are compared. The result shows that the frequency increases, when thepile - soil - structure Interaction is considered. In addition, the maximum displacementand the maximum stress of the tank decreases.(4)Two conditions are considered in this dissertation. This dissertation comparedthe seismic responds of the two conditions under different seismic waves. In the samecondition, the seismic responds under Castaic wave are greatest. The responds underartificial wave are smallest.(5)This dissertation takes the actual project as the background, and uses thebranch modality-two step analytic method. This dissertation has made a more accuratemodel, which provides a reference for seismic analysis of other similar structures.