随机杆件初弯曲对K6型网壳稳定承载力的影响研究

Research on the Influence of Random Initial Curvature of Members on the Stability Bearing Capacity of K6 Reticulated Shell

单层网壳属于缺陷敏感型结构,初始缺陷对其稳定承载力影响较复杂。为研究随机杆件初弯曲对网壳整体承载力的影响,以K6型单层球面网壳为对象,推导了实现具有杆件随机初弯曲网壳的相关公式,并详细阐述了其在有限元程序中的实现方法,分别研究了杆件初弯曲幅值、弯曲方向角及二者耦合作用对网壳结构稳定承载力的影响程度。主要得出如下结论:当初弯曲幅值δ取为确定值l/1 000时,与理想网壳相比,承载力下降5%左右;当δ取为确定值l/250时,承载力下降14%左右。与随机初弯曲幅值相比,初弯曲方向角对网壳结构稳定承载力的影响较小。同时考虑弯曲幅值与弯曲方向角的随机性时,杆件初弯曲对网壳稳定承载力的影响更为显著。推导的建模公式及其有限元方法可推广至其它类型的空间网格结构中。

Single-layer reticulated shell is sensitive to imperfections,due to its complex effects on the stability of reticulated shell.To evaluate on the influence of random initial curvature of members on the load-carrying capacity of K6 reticulated shell,the related formulas establishing K6 reticulated shell with random initial curvature of members are widely developed,and the realization method of these formulas in finite element package is illustrated in details.The influences of initial curvature amplitude,angle and both of them on load-carrying capacity of K6 reticulated shell are investigated.The main conclusions are summarized as follows.Compared with perfect shell,limit load reduction of reticulated shell with amplitudeδ=l/1 000 andδ=l/250 is about 5%and 14%,respectively.Amplitude of member curvature has larger effect on load-carrying capacity than angle of member curvature.The effect of initial curvature of member becomes more obvious when their randomness is taken into consideration.Developed related formulas and its realization method in finite element package can be extended into other space frame structures.