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应变模态差法多用于刚性结构的损伤识别,而较少用于柔性结构。索桁架-索网结构是柔性组合结构,该结构通过预应力索提供刚度,结构损伤的主要因素是索的损伤和预应力损失。基于有限元模态分析提取结构损伤前后的应变模态差作为损伤识别指标,应用应变模态差法对索桁架-索网结构进行计算分析。结果表明:索单元发生损伤后,通过应变模态差能够准确地识别索不同位置的损伤,同时对小损伤(损伤程度10%)较敏感;得出应变模态差与损伤程度的关系曲线,该曲线在不同工况下能够很好地判断索单元损伤程度;利用应变模态差能够识别出索的预应力损失的位置,并可大致判断损失程度;验证应变模态差损伤识别方法可以较好地用于索桁架-索网结构的损伤识别。
Strain modal difference method is mostly used for the damage identification of rigid structures, but less for flexible structures. Cable truss - cable network structure is a flexible composite structure, which provides rigidity through the prestressed cable, the main structural damage is cable damage and prestress loss. Based on the finite element modal analysis, the strain modal difference before and after structural damage was extracted as the damage identification index, and the truss-cable net structure was calculated by using the strain modal difference method. The results show that after the cable unit is damaged, the strain modal difference can accurately identify the damage in different positions of the cable and is more sensitive to small damage (damage degree 10%). The relationship curve between the strain modal error and the degree of damage is obtained, The curve can be used to judge the damage degree of cable element under different working conditions. Using the difference of strain modalities, the position of cable pre-stress loss can be identified and the damage degree can be roughly judged. Good for cable truss cable network damage identification.