Seismic analysis of desulfurization tower

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This post was last edited by kareale88 on 2019-1-23 at 19:43; the file bg4.png was also updated. This desulfurization tower is constructed entirely of steel, and its modeling and analysis were carried out using ANSYS WORKBENCH 19.0. Shell elements of type SHELL181 were used for the shell, flue openings, and ring beams of the tower, while beam elements of type BEAM188 were used for all fillers and reinforcing supports. There are four main theories used for the seismic analysis of such structures: static theory, dynamic theory, response spectrum theory, and time-history response theory. The static theory approximates the equipment as a rigid body, assuming that the seismic acceleration at all points of the equipment is the same as that at the foundation, while ignoring the flexibility of the equipment itself; this approach is not suitable for tall structures. The dynamic theory primarily conducts calculations by assuming the dynamic coefficient to be a constant, with the intermediate dynamic coefficient being obtained through interpolation; this theory was mainly applied in the Soviet code \"Code for Buildings in Seismic Zones\" prior to 1951. The response spectrum theory is the most widely used theory for seismic analysis worldwide. This theory considers the structure of a facility to be an elastic body, and determines the maximum response of the structure during an earthquake based on the structure’s natural vibration characteristics and the type of soil in the area. Calculations are then carried out using static theory based on this response. Time-history analysis is a dynamic analysis method that can fully simulate the entire behavior of a structure during an earthquake; it is the most accurate simulation technique, but it has the drawback of requiring a long calculation time. This paper conducts seismic analysis of the desulfurization tower using the response spectrum method in accordance with the standard GB50011-20110 \"Code for Seismic Design of Buildings\". Since the response spectrum theory requires determining the maximum response of a structure under seismic loads based on its natural vibration characteristics and other factors, a modal analysis that takes into account the effect of service load prestress must be conducted on the structure before performing response spectrum calculations. This is done in order to determine the number of modes to be used for mode decomposition and combination calculations. According to relevant guidelines, the percentage of the effective mass involved in the modal analysis relative to the total mass should be no less than 0.9. After the modal analysis is completed, a response spectrum analysis is carried out based on the obtained mode shapes. In accordance with the GB50011 seismic code, in order to fully account for the effects of earthquakes on the components of the equipment in all directions, during the response spectrum analysis, the seismic acceleration spectra for the three directions are input separately for calculation, and then load combinations are applied to conduct seismic capacity checks on the sections. The seismic response spectrum curves used in this analysis are those from the seismic code GB50011 – specifically, the seismic influence coefficient curves: http://www.asimi8.com/data/attachment/forum/201901/23/145116qj30ussl0d00rvun.png. After the calculations for various seismic scenarios are completed, the load combination factors specified by the seismic code are applied to determine the final combined stresses. The results are then evaluated in accordance with relevant standards. It should be noted that for such tall structures, in addition to assessing strength and stability, the deflection at the top of the tower also needs to be considered. http://www.asimi8.com/data/attachment/forum/201901/23/151030bzfw8zr5wmnjqzd0.png http://www.asimi8.com/data/attachment/forum/201901/23/151135j8uk9t7kns9udsyn.jpg