装配式落地粮食波纹钢板筒仓在粮食荷载作用下稳定性研究

Stability of prefabricated ground-supported corrugated steel silo under loading of grain in bulk,whose silo sheeting,as orthotropic plate, being under circumferential tension mainly due to one direction stiffness,whose vertical stiffness,loaded by axial force absolutely,depending on buckling of vertical stiffener,indicates contrary conclusion compared with current design theory,converting the problem to stability of cylindrical shell wall with equivalent thickness.Therefore,no requirements about stability on vertical stiffness were refered in current design code.Both experimental study and numerical simulation be used in this applying plan,to explore buckling mechanism of prefabricated ground-supported silo induced by unstability of vertical stiffness. First,initial geometrical imperfections,be adopted based on enough field surveys,consistent mode or advanced stochastic method,then orthogonal anisotropic mechanical properties of corrugated silo sheeting be obtained in terms of experiment, double nonlinear FE analysis be executed,based on partial compatibility initiated by high strength bolt bearing type connection,variable axial force,n-stepped column,to analyze buckling of whole structure.Compared experimental results,based on a new kind of measurement system executed in the test procedure,with theoretical ones,thus numerical model be modified,both theoretical and experimental results contribute to the calculation of effective length coefficient of vertical stiffness,which is key evidence to stability design theory of prefabricated corrugated ground-supported steel silo.

装配式落地圆形粮食波纹钢板筒仓在粮食荷载作用下，因仓壁板为正交各向异性板，环向刚度大，故主要受拉，竖向刚度很小，故不考虑受力，竖向外荷载完全由竖向加劲肋承担，因此该类筒仓稳定性实际取决于其竖向加劲肋稳定性。但目前设计计算理论是将其视为圆柱壳屈曲，即仓壁在内压及竖向荷载作用下的稳定性，这显然与其实际受力状况不符。本课题将通过模型试验和数值模拟相结合的方法，研究竖向加劲肋屈曲诱发筒仓失稳破坏的机理。首先，基于实仓安装几何偏差调研、结合一致缺陷模态或改进随机缺陷法得出适当的初始几何缺陷形式；试验测得仓壁板各向异性力学指标；数值模型考虑高强螺栓承压型连接的位移部分协调性，建立考虑几何、材料非线性有限元模型，研究变轴力作用下多阶变截面竖向加劲肋稳定性；通过提出一种新型测量变形系统，测试模型仓结构失稳破坏全过程，从而验证和修正数值模拟所得计算长度系数，最终为该类筒仓稳定性设计提供合理理论依据。

项目研究重点是装配式落地粮食波纹钢板筒仓稳定性。首先，将竖向加劲肋视为多阶变截面柱，运用稳定理论推到了屈曲方程，得到其计算长度系数公式，与有限元线弹性屈曲分析得到的计算长度系数比较，结果表明数据可靠准确。将该系数应用于装配式粮食波纹钢板筒仓模型设计，结果表明竖向加劲肋截面尺寸过大，明显不合理。说明，装配式粮食波纹钢板筒仓竖向刚度不仅由竖向加劲肋提供，还应包括波纹仓壁板，尽管其竖向刚度弱。提出了一种新型有限元模型，将波纹仓壁板视为正交各向异性壳，从多种本构方程理论中确定了方程各元素合理取值，计算考虑了几何非线性，初始缺陷极值来自于对多家主流钢板仓公司测量实仓数据，采用连接件单元模拟高强螺栓连接，计算模型实现了装配式粮食波纹钢板筒仓失稳全过程模拟，所得结果不仅指导完成了试验模型设计，还弥补了我国现行《粮食钢板筒仓设计规范》（GB50322-2011）关于装配式粮食波纹钢板筒仓稳定性计算的不足。