初始几何缺陷对开敞圆柱储罐风致屈曲的影响分析

Many large open-top cylindrical tanks are prone to buckling failure due to the combination of internal and external wind pressures, which is very sensitive to initial geometric imperfections, while the consistent imperfection modal method commonly used does not take into account the random effect of actual tank imperfections. Therefore, the stochastic imperfection modal superposition method was adopted, the initial imperfection was represented by the superposition of the first ten buckling eigenmodes and corresponding participation coefficients were treated as random variables following the normal distribution. Through Monte Carlo simulation, the stochastic nonlinear buckling analysis was carried out on 1 000 samples. The results show that the first order buckling eigenmode is not always the most unfavorable initial imperfection shape of open-top tanks, but the difference of buckling capacity is no more than 1%, indicating that the consistent imperfection modal method can be used in practical engineering for convenience. The smaller the ratios of height to diameter and radius to thickness, the more sensitive the tank to initial imperfections. Tanks reinforced with stiffeners are more sensitive to initial imperfections than unreinforced tanks. Besides, an empirical formula to estimate the imperfection sensitivity of open-top tanks with different geometries was obtained through parameter fitting, which was in good agreement with the finite element results.