空间钢支撑框架损伤诊断研究

Damage Diagnosis of Steel Braced Space Frame Structures

为诊断空间钢支撑框架的损伤,提出了两阶段损伤诊断法。该方法综合了损伤定位向量法和特征灵敏度分析。推导了空间梁、柱和支撑单元的特征应力计算公式,定义了连接单元的特征应力,推导了模态参数差量对结构模型参数的一、二阶灵敏度和梁端连接损伤的梁单元刚度矩阵。完成了一个空间钢支撑框架模型损伤诊断试验,模拟了支撑损伤和连接损伤的7种损伤模式。采用力锤激励方式,使用特征系统实现算法识别模态参数;使用损伤定位向量法判定可能损伤单元,采用二阶特征灵敏度分析确定可能损伤单元的损伤程度。结果表明,当杆件或连接损伤达到一定程度时,两阶段损伤诊断法能有效诊断损伤。

To diagnose the locations and extent of damage in steel braced space frame structures, a two-stage damage diagnosis approach is proposed. This approach is comprised of the damage locating vectors method and eigensensitivity analysis. The formulas for evaluating the characterizing stresses in beams, columns and braces are derived, and the characterizing stresses in connections are defined. The first and second-order sensitivities of the modal parameters discrepancies with respect to the structural model parameters and the stiffness matrix of beam elements with one damaged end are derived. An experiment on damage diagnosis of a steel braced space frame model is carried out. Seven damage patterns, including the brace damage and connection damage, are simulated. Hammer impacts are employed as excitations to the structure model, where the parameters are extracted by the eigensystem realization algorithm. The damage locating vectors method is utilized to determine potentially damaged elements, and then the second-order eigensensitivity analysis is employed to estimate the extent of damage of the potentially damaged elements. It is demonstrated that the two-stage damage diagnosis approach is effective when the damage of the members or connections achieves a certain level.