中文摘要：

针对识别门式起重机主梁结构缺陷的问题，将移动载荷法应用到结构缺陷识别中。通过三维建模软件UG，建立了单主梁门式起重机的整机模型，在Ansa中形成其有限元模型并进行了网格划分，最后基于有限元分析软件ANSYS对质量为100kg载重物在起重机主梁上移动的工况进行了模拟，得到了4种不同缺陷尺寸的模型在该工况下特定振型的固有频率曲线。研究结果表明，缺陷尺寸和载重物离开缺陷位置的距离是影响起重机特定振型固有频率的两大关键因素，该结果为起重机无损检测提供了重要依据。

英文摘要：

Aiming at recognizing the structural defect of gantry crane, the moving load method was investigated. The three-dimensional model of a single main beam gantry crane was established with UG, then the finite element model of this crane was formed and mashed with Ansa. Finally, a condition that an object in mass of 100 kg moving along the main beam of the crane was simulated with ANSYS, under this condi- tion, natural frequency curves in specific vibration modes of four models with different defect sizes were obtained. The results indicate that the sizes of deferent detects and the distance between the moving load and the detects are two key factors that affect the natural frequencies in specific vibration modes of this crane, this result provides an important basis for non-destructing testing and evaluation of the crane.