基于损伤部位向量法的钢框架损伤识别研究

DLV-based research on damage identification of steel frame

对损伤部位向量(DLV)法作了简单介绍,并用该方法对钢框架进行了损伤识别和损伤定位。该方法假定结构损伤前后为线性,对结构损伤前后柔度矩阵差进行奇异值分解,将奇异值为零所对应的向量,作为静荷载施加在无损结构的测点位置,则应力为零的单元为可能损伤的单元。对3种不同工况的钢框架进行了振动模态试验,用前3阶模态参数构造框架的柔度矩阵,按照DLV法对其进行了损伤识别,识别结果与已知损伤情况相一致。从测试自由度不完备、噪声和振型质量归一化系数这3个方面对识别效果进行了分析,结果表明:当损伤使结构动力特性有微小改变时,使用该方法不易定位损伤,应结合局部损伤识别方法进行判定;当损伤使结构动力特性有较大改变时,该方法能有效识别损伤的单元。DLV方法概念简单,理论明确,不受结构类型的限制,不需要结构的数学模型和模型缩聚或扩展技术,只需获得结构损伤前后的前几个低阶模态参数,即可识别结构一处或多处损伤,实际应用时可操作性强。

In this paper,Damage Location Vector（DLV）method was introduced.A structure can be treated as linear in pre and post damage states,flexibility matrix was synthesized before and after damage and the incremental flexibility matrix was computed.According to singular value decomposition（SVD）,ones can get several vectors corresponding to zero singular value;these vectors have the property that when they are applied to the undamaged structure as static forces at the sensor locations,the element which stress is zero will be potentially damaged elements.Vibration modal test was carried out for the steel frame and different extent damaged steel frame,the modal parameter were obtained and the flexibility matrix was constructed.DLV method was utilized to locate the damaged element,recognition results is consistent with the known damage.From several aspects,such as the incompleteness of measured DOFs,noise and modal mass-normalization constants,the identification results analysis was performed.It demonstrates that unsatisfatory detection occurs for the less damaged element,so it should be combined with the local damaged identification method.The DLV method is effective when the damage extent reaches a certain level which results in the major change of structural dynamic characteristics.The DLV technique is conceptually simple and theoretically tractable,It does not set a limit to type of structure,need not mathematical model and needs only several lower modal parameters of structure before and after damage for identifying single or multi damage of structure and the technique can operate well.