Study On The Structure Dynamic Characteristics And Performance-based Seismic Design Method Of High-rise Thin-walled Cylindrical Structure With Large-openings

The thin-walled shell structure has its major advantages on long-span,material weight, overall structural strength and rigidity. The structure form andload condition of cylindrical shells with large-openings are complex and theinfluence factors on the stability are various. But there are many problemsunsolved of the structure dynamic response under seismic. And it has nocorresponding standard of performance-based seismic design to be follwed for thethin-walled shell structure with large-openings.This research was studying the dynamic structural responses of thethin-walled shell structures with large rectangular openings. In terms of evaluatingthe impacts on the dynamic responses regarding the number and location of theserectangular openings, two types of seismic waves (i.e., long period and shortperiod) with different acceleration peaks and input directions were applied. Theworst case scenario for the input angle of the seismic wave was also analyzed.A simplified numerical method of pseudo-static structural calculation wasderived based on the analysis on the dynamic responses of the same structures,using the finite element method for the scenarios with and without fluid-solidcoupling. The confirmation modeling was completed with a1:15physical modelof a large-scale desulfurization tower using the shaking table method. Accordingto the analysis, the major tasks and founds are as follows:(1)The numerical modeling of the targeted desulfurization tower wassimplified under the principles of1) the weights are identical and2) the dynamiccharacteristics are similar. The modeling was completed by inputtingmulti-direction seismic waves and the peak acceleration, distribution pattern ofdisplacement on structure top under these waves were generated. Throughanalyzing the modeling results, the vulnerable locations of this type of structurescan be determined and the simplified numerical calculation method was derived.The worst case scenario of wave input angle was also obtained.(2)The physical modeling was carried out with a1:15reduced scale model to the large-scale desulfurization tower using shaking table method. The modelingdata were generated with applying2types, multi-direction seismic waves withdifferent liquid surface elevations in the structure. The modeling simulationoutputs confirmed the calculation results using the numerical method, regardingthe worst wave input direction. Furthermore, the physical modeling provided anumerous of useful data for the structure calculation regarding the impacts of theconcentration rate of the liquid contained in the structure.(3)In terms of deriving the peak acceleration distribution patterns,displacements on the structure top and impact behavior on the responses (i.e., thedynamic responses of thin-walled shell structure) caused by liquid-solid couplinginteraction during earthquakes, the dynamic responses were analyzed with andwithout liquid-solid coupling using the two numerical models (the prototypedesulfurization tower and simplified thin-walled shell structure). The researchfocused more on peak acceleration alteration along with the increase of the liquidsurface and concluded that the liquid vibration scope and its energy is extremelyincreased at the liquid surface area, and causes overturning momentum. Thisfound can determine the threshold of uplift phenomenon occurring. It alsoconfirmed that the liquid contained will create extra momentum at the structurebottom because the liquid is "pushing" the structure wall to gain the requiredacceleration force and this "shell vibration" will be more severe along with theincrease of the liquid depth. Therefore, it is critical to take the "liquid-solidcoupling" into account regarding the thin-wall structures with large-span opening.(4) The method of structure performance-based seismic design was studied.This research also provided some references and recommendations for the relatedengineering coding and similar structure design in the future, based on thenumerical model and physical model analysis on thin-wall shell structure withlarge opening. These recommendations include some design standards andparameters, such as the wall thickness, input angle of the seismic waves and somemethodology of calculation simplification.