Analysis And Design Of An Unbonded Prestressed Egg-shaped Digester

Digester is an important part of wastewater treatment plant in municipal projectand the Egg-Shaped Digester will be the best one. Higher requirements in design ofdigester have been brought forward because of its big special structure andcomplicated loads. First, this paper introduces the research actuality in China and in the world andthen analyzes the theory of calculating. On the basis of the achievements of the older,the work of this paper is made sure. As for Egg-shaped Digester, more accurate result can be acquired if thethickness of wall is exact. This paper introduces the method of imitating the wall ofEgg-shaped Digester to a conic which is changing with the height of the wall. The action of unbonded prestress bar to digester and the method of prestressapplying to structure is an important part in this paper. The prestress of each bar isreplaced by the equivalent pressure with the equivalent load theory, which is appliedto the wall of digester when calculating. The models of the two big digesters are calculated under ANSYS80 software,and analyzed the internal force and deformation under static loads. It is found that thedigester is mainly controlled by the round internal force and vertical moment. Whenthe digester is empty and when it is acted by temperature and other loads are the twodisadvantageous condition. In the next seismic analysis, we use iterative method to analyze the reaction ofdigester under Tianjin wave,Rengong wave and taft wave. We find that the graphs ofresults under each wave are similar to the graphs of results under static loads.Moreover, the value of results under Tianjin wave is the higher. We also find that thesymmetrical internal forces go smaller from 0 degree to 90 degree with the directionof seismic wave inputting, while the unsymmetrical internal forces go higher. The seismic wave can change the condition under static loads.