基于单元应变模态差的网架结构损伤诊断研究  

Damage diagnosis of space truss based on change of elemental strain modal

作　　者：李永梅[1] 高向宇[1] 史炎升[1] 周锡元[1] 

机构地区：[1]北京工业大学建筑工程学院,北京100022

出　　处：《建筑结构学报》2009年第3期152-159,共8页Journal of Building Structures

基　　金：国家自然科学基金资助项目(50678013);中国博士后科学基金资助项目(20060390387)

摘　　要：对具有一定程度损伤的网架结构来说,常规的结构有限元分析或实验模态分析得到的位移模态和频率难以有效地反映结构的损伤状况。为了提高诊断效率与诊断结果的可靠性,根据空间杆系结构的受力特点,利用两节点空间铰接杆单元有限元法,由节点位移模态推导出单元应变模态,提出采用结构损伤前后的单元应变模态差作为网架结构损伤定位的识别指标,并以损伤单元应变模态的差值大小确定损伤程度。通过对一个典型网架结构的数值模拟研究表明:该方法能够在低阶模态条件下,有效识别网架结构不同位置和程度的局部损伤;且在一定噪声水平下具有较强的鲁棒性,适用于实际观测条件下的网架结构损伤定位。Frequency and displacement modal indices are inefficient to reflect structural damage when using conventional finite element or experiment analysis for damage diagnosis of truss structure. In order to improve efficiency and reliability for damage diagnosis, based on the characteristics of space truss structure, element strain modal can be obtained by nodal displacement modals by means of the finite element method on space truss element connected by pin between two nodes. Therefore the change of elemental strain modal is presented as new dynamic indicator for damage locations of space truss structure. Furthermore, damage degree can be derived from the value of the change of damage elemental strain modal. A numerical example for a spatial truss is provided to verify the practicability of the method. The results show that it is effective to locate damage and assess damage degree only by lower modes. Moreover, the results indicate that the proposed method based on strain modal of truss element can accurately identify damage location of space truss structure with the noisy modal data.

关 键 词：网架结构 杆单元 应变模态 损伤诊断 

分 类 号：TU356[建筑科学—结构工程] TU311.3