桥墩模态分析的一种新方法

New Method of Pier Modal Analysis

以既有实测资料的桥墩为原型,用三维块体单元模拟墩身,用GOODMAN无厚度单元模拟桥墩与地基土的相互作用,建立了考虑三维耦合有限元单墩模型。并利用现场测试资料,对模型进行了验证和参数优化。然后分析不同基底约束、不同单元形式和不同墩身截面形状对桥墩自振特性的影响。对几座典型桥墩进行了自振特性的仿真分析。经与实测值对比,建立的三维实体单墩模型能够比较准确地计算各种桥墩的自振频率。计算表明,圆端型桥墩与截面积相等的等效矩形桥墩的自振特性非常接近,因此,仿真计算中可用矩形桥墩代替圆端形桥墩,可以节省计算资源,简化建模工作量,而且误差较小。

Based on the prototype of the measured pie r data, a 3D coupled finite element pier model is built, where the interaction of the pier and the foundation soil is simulated with GOODMAN contact element. The measured data is used to verify and modify the model. Affects on the free vibra tion characteristics of the pier by different bottom constrains, different elem ent types and different cross sections are studied. The natural characteristic s imulation of some typical piers is carried out. The simulation shows that the n atural vibration characteristics of the pier with round-end section is similar to that of rectangular section. Therefore the latter can replace the former to s implify model building, save calculation resources and increase accuracy.