平面型弦支结构体系及超越雪荷载下的弹塑性分析

平面型弦支结构体系是一种被广泛认可和应用的新型预应力大跨度结构体系。对平面型弦支结构在形态分析、静动力性能和施工过程分析等方面的研究现状及工程应用情况进行综述,指出关于平面型弦支结构弹塑性分析缺乏的现状。结合近年来频发的暴雪灾害,指出超越雪荷载下开展平面弦支结构弹塑性分析的必要性。在超越雪荷载作用下,数值模拟平面型弦支结构弹塑性极限状态的发展过程,得到平面弦支结构在全跨和半跨超越雪荷载作用下的屈服机制和失效机制,并给出其内力重分布规律和荷载传递规律,为实际工程在超越雪荷载下的分析和设计提供理论依据。

Probabilistic Tolerance Method for Omitting Small Fatigue Loads

The simplification of fatigue load spectrum,which can effectively reduce experimental cost,is of great importance for structural fatigue tests.By introducing random variables,the probabilistic tolerance method of removing small amplitude cycles proposed in this paper takes into account the randomness of both load and fatigue limit.The probability of the damage occurrence caused by the removed small loads is calculated to ensure that it cannot exceed the given probabilistic tolerance.Accordingly,the omission level is obtained and the truncated spectrum is formed.The unnotched aluminum sheet specimens are used to perform the fatigue test on the original fatigue spectrum and truncated fatigue spectrum of a transporter.The test results show that there is no statistical difference between the test life of the truncated spectrum and that of the original spectrum,which demonstrates the validity of the small-load-omitting method that considers randomness.

大跨度张弦梁结构易损性及评估分析

由于超越荷载和罕遇地震的作用,大跨度张弦梁结构可能由此而发生整体或连续倒塌。考虑结构和抗力的不确定性,分析了在超越荷载和罕遇地震下结构的易损性。首先,基于蒙特卡洛法和拉丁超立方抽样法,研究活荷载的超越幅度与结构失效概率之间的关系,绘制其静力易损性曲线;其次,基于增量动力时程分析方法,研究不同地震波作用与结构失效概率之间的关系,绘制结构倒塌易损性曲线;最后,研究不同预应力水平对其易损性的影响。结果表明,基于易损性曲线可预测结构在超越荷载和罕遇地震下的失效概率;大跨度张弦梁结构易损性较低;适当提高预应力水平,可以改善结构易损性。