Effect of spatially correlated initial geometric imperfection on reliability of spherical latticed shell considering global instability
Effect of spatially correlated initial geometric imperfection on reliability of spherical latticed shell considering global instability
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考虑全局不稳定性的空间相关初始几何缺陷对球网壳可靠性的影响
DOI：
10.1016/j.strusafe.2019.101895
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发表时间：
2020
影响因子：
5.8
通讯作者：
H.P. Hong
中科院分区：
文献类型：
--
作者：
X.Z. Cui;Y.G. Li;H.P. Hong
网壳结构由于其结构性能好、重量轻、施工方便等优点，在大跨度结构中得到了广泛的应用。它们的规范化设计通常由重力载荷的全局失稳要求和最大初始几何缺陷（IGI）的指定形状和幅度决定。分配形状和最大IGI的可靠性基础未知。在本研究中，建议IGI建模使用同步自回归模型。结果表明，该模型在模拟空间变化的相关缺陷方面是灵活的，可以科普不规则的网格系统。利用该模型，分析了空间相关IGI对按我国规范设计的球面网壳结构整体失稳承载力概率分布和可靠度的影响。结果表明，使用的前缀形状的IGI评估的承载能力的概率分布是不保守的相比，通过使用空间变化的随机缺陷。前者的概率分布的形状不同于后者。可靠性分析结果表明，如果规范中规定的最大IGI约等于IGI标准差的2 ~ 3倍，则使用规范中实现的临界荷载系数2导致整体失稳的失效概率小于约10− 6。如果设计使用临界载荷系数1.5，则该失效概率将小于约10 - 5。建议将规范推荐的临界荷载系数降低到1.5，同时达到设计规范标定时经常采用的目标可靠指标。
Latticed shells are extensively used for large-span structures because of their good structural behaviour, lightweight and ease of construction. Their codified design is often governed by the global instability requirement for gravity load and specified shape and amplitude of maximum initial geometric imperfection (IGI). The reliability basis for the assigned shape and maximum IGI is unknown. In the present study, it is proposed that IGI is modelled using the simultaneous autoregressive model. It is shown that this model is flexible in modelling spatially varying correlated imperfection and can cope with irregular grid system. By using this model, the effect of the spatially correlated IGI on the probability distribution of the load capacity for global instability and the reliability of spherical latticed shell designed according to the Chinese design code is assessed. It is shown that the use of the prefixed shape of the IGI to assess the probability distribution of the load capacity is unconservative as compared to that by using spatially varying random imperfection. The shape of the probability distribution for the former differs from that for the latter. The reliability analysis results indicate that the use of a critical load factor of 2 implemented in the code leads to a failure probability less than about 10−6for global instability if the specified maximum IGI defined in the code equals about two to three times the standard deviation of IGI. This failure probability becomes less than about 10−5if a critical load factor of 1.5 is used for design. It is suggested that the code recommended critical load factor may be reduced to 1.5 while achieving target reliability index often adopted for design code calibration.
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