考虑质量变化的刚架结构损伤识别方法研究

Study on damage identification frame structures considering mass change

结构构件出现缺口损伤时,伴随着结构质量的减小。为了更精确地识别结构损伤,以折减损伤单元截面积来模拟结构损伤,提出考虑结构质量变化的刚架结构损伤识别方法。该方法首先通过相对模态应变能指标对结构损伤进行准确定位;之后考虑梁单元截面特性变化的特点将单元刚度矩阵进行分解,以多个指标描述单元损伤,从而建立结构损伤程度识别方程,并用最小二乘方法对损伤指标进行求解。数值算例结果表明,本文方法能实现对刚架结构损伤位置的准确定位和损伤程度的精确识别,而且具有良好的抗噪性。

Because damage is accompanied by the decrease of the mass of the structure when structural elements have gaps,a damage identification method considering mass change was presented.Here,structural damage was defined by the reduction of element cross-sectional area.Firstly,Fractional modal strain energy index was applied to detect the damage position precisely,then the elemental stiffness matrix was considered as the combination of stiffness matrices contributed by different sectional properties,and multiple indexes were used to describe elemental damage.Subsequently,the least-square technique was used to solve damage equation with multiple indexes.Numerical example results indicated that the proposed method is capable of realizing the accurate damage localization and the precise damage quantification considering even a certain noise level.