不同破坏模式下锥体结构冰力定性分析

Qualitative analysis of ice forces on conical structures under different failure modes

采用弹性基础板模型,对锥体结构上冰破坏力随不同弯曲破坏模式而变化的关系进行了定性分析,给出了由2个尺寸比表达的与3种破坏模式相对应的冰荷载表达式和1个由尺寸比定义的破坏模式图.利用这一结果揭示了弯曲破坏冰力幅值与周期大幅度变化的力学机理.板型弯曲破坏冰力是尺寸比k1的减函数;楔梁型破坏冰力是k1的增函数.这预示着最大冰力将在两种破坏模式过渡时出现.冰力周期随冰的断裂长度与其厚度之比k2增大而增长,当k2大于5时,破坏模式由板型过渡到楔梁型.该结果可在现场数据分类识别和冰力速度效应的定性分析等方面得到应用.

A qualitative analysis is made for the relationship between the cone loads and their corresponding bending failure modes of sheet ice by using thin-plate theory on elastic foundation. A failure mode map is presented, as well as the three formulae of ice loads expressed by two size ratios. By using these results, the mechanism of changing of amplitude and period of ice force over a wide range can be explained. The ice force with plate-type bending failure is a decreasing function of size ratio k1; the ice force with wedged beam-type failure is an increasing function of size ratio k1. This predicts that a maximum ice force will take place under the transition condition. Along with the increasing of the ratio of breaking length with thickness of ice k2, the period of ice force will be increased. When k2 is getting to be greater than 5, the failure mode of ice transforms from plate-type into wedged beam-type. Some applications of this result can be made for classifying and identifying the test data and analysis of velocity effects of ice force qualitatively.