Fluid-Solid Interaction Analysis And Dynamic Reliability Analysis Of Prestressed Egg-shaped Digester

Fluid-solid coupling problem is a front research subject which is paid close attention to extensively. Egg-shaped digesters in China are usually constructed on pile-group foundations or diaphragm walls to resist the dynamic effect of earthquake. Because the fluid-solid interface of prestressed egg-shaped digester is conical and thickness of cross section is varying, the dynamic liquid pressure and the resulting reactions are rather difficult to gain. Through the computer program ANSYS, seismic evaluation of the digester is performed using a 3D finite-element model that includes the effect of fluid-solid interaction. Comparisons of calculated responses and those of shaking table tests show reasonably good agreement. It demonstrates that this finite-element model is reasonable and can be applied to the engineering design. Moreover, the approximate equation for evaluating the dynamic liquid pressures in egg-shaped digesters at arbitrary levels is proposed.The probability density evolution method for random vibration analysis of stochastic structures has developed in recent years. Numerical analysis of the digester, including model with random elastic modulus of concrete, model with random boundary conditions and prototype with random earthquakes, are investigated. The results demonstrate that the probability density evolution is efficiency.It is found that the response results of arbitrary three seismic waves taken according to the criterion are partial to unsafety. The random model based on physics can give the distribution of probability and we can carry through the aseismatic design based on structural reliability.Finally, discussing about the further research direction briefly.