基于动力特性的螺栓连接钢框架结构有限元建模

Finite Element Modeling of Bolted Steel Frame Structure Based on Dynamic Characteristics

合理选取螺栓节点处理方式与确定层间柱有效长度,是螺栓连接钢框架结构有限元建模的难点所在。首先对3层螺栓连接钢框架结构室内模型进行了动力特性测试,然后采用ANSYS分析软件开展了结构三自由度集中参数有限元模型和板-梁有限元模型的动力特性分析。板-梁有限元模型的螺栓节点分别按铰接、半刚性连接、刚接处理。通过对比结构前3阶模态的自振频率、振型的有限元值与实测值发现:螺栓节点按半刚性处理较为合理。为了进一步提高半刚性节点处理板-梁有限元模型的精度,将模型的实测动力特性值代入三自由度集中参数模型,反推结构层间柱的实际有效长度,并对有限元模型进行修正。研究表明:在结构层间柱的实际有效长度修正后,结构动力特性的计算精度可以得到进一步提升。

The finite element modeling of bolt connection steel frame structure has the difficulties such as reasonable selection of bolt joint treatment and determination of effective length of interlayer column. Firstly, the dynamic characteristics of a three-layer bolted steel frame structural model are tested. Then, the dynamic characteristics of the finite element model of structural three-degree-of-free- dom concentrated parameter and the plate-beam finite element model are analyzed by ANSYS software. The bolt nodes of the plate- beam finite element model are treated as the hinge, the semi-rigid connection, the rigid connection, respectively. By contrasting the first 3 order natural frequencies and vibration modes between the finite element values and the tested values, it is found that the semi- rigid treatment of the bolted joints is reasonable. In order to further improve the accuracy of the finite element model of the plate-beam interaction with the semi-rigid joints, the measured dynamic characteristic values of the model are substituted into the three-degree-of- freedom concentration model, and then, the effective length of the inter-column is calculated and the finite element model is modified. The results show that the calculation accuracy of structural dynamic characteristics can be further improved after the practical effective length of structural columns is corrected.