Damage identification method of beam string structures with improved configuration based on modal parameters

In order to clarify the damage identification method applicable to each member type of beam string structures with an improved configuration of lower chords and struts, and to reduce misjudgments at non-damaged members, this paper proposes a damage identification index based on sub-component curvature variation and structural modes. The validity of the index was illustrated by analyzing a simply supported beam structure with a simple structural form. The finite element software ANSYS was used to establish the analysis model of beam string structures with an improved configuration of lower chords and struts. The damage of the members was simulated by reducing the elastic modulus of the member elements. Considering the symmetry and complexity of the structure, damage conditions of single damage, multiple damage, and small damage level were set up on the members at the mid-span, quarter-span, and near the bearing ends, respectively. The improved curvature absolute difference index of sub-components and the sub-component curvature variation based on structural mode proposed in this paper were used for the comparative analysis of damage identification. The findings demonstrate that the index of sub-component curvature variation based on structural modes can achieve the precise localization of single and multiple damages in the structure. This index is also highly sensitive to slight damage, making it an effective method for identifying damage to beam string structures with an improved configuration of lower chords and struts.

为明确适用于下弦杆与撑杆优化配置型张弦梁结构（Beam String Structures）各构件类型的损伤识别方法，减少非损伤构件的误判，本文提出了一种基于子构件曲率变化（Sub-component Curvature Variation）与结构振型（Structural Modes）的损伤识别指标。本文通过分析结构形式简洁的简支梁结构，验证了该指标的有效性。采用有限元软件ANSYS建立了下弦杆与撑杆优化配置型张弦梁结构的分析模型，通过折减构件单元的弹性模量来模拟构件损伤。考虑到结构的对称性与复杂性，分别在跨中、四分点以及支座附近的构件上设置了单点损伤、多点损伤与低损伤程度的工况。本文将提出的改进型子构件曲率绝对差指标与基于结构振型的子构件曲率变化指标开展损伤识别对比分析。研究结果表明，基于结构振型的子构件曲率变化指标可实现结构单点与多点损伤的精确定位，且对微小损伤亦具备较高灵敏度，可为下弦杆与撑杆优化配置型张弦梁结构的损伤识别提供有效技术手段。