混凝土斜拉桥动力有限元建模与模型修正

Finite Element Modeling and Model Updating of Concrete Cable-stayed Bridge

为建立准确可靠的混凝土斜拉桥动力基准有限元模型,对1座大比例(1∶15)Π形截面主梁混凝土斜拉桥试验模型进行了模态测试,分别采用单主梁模式、三主梁模式、梁壳模式和实体模式建立了斜拉桥的初始动力有限元模型;以实测数据为依据,采用基于灵敏度的模型修正技术分别对以上初始有限元模型进行了修正,将修正前后的动力特性计算值与实测数据进行对比,讨论了不同模式建模方法的计算精度和模型修正效果,以及有限元建模的误差来源和模型修正的相关问题。结果表明:初始有限元模型计算误差主要是由建模误差和参数误差引起的;梁单元模型在建模方面有局限性,应根据不同的结构特点和分析目标建立相应的有限元模型;模型修正应与试验相结合,对引起有限元模型计算误差的各种因素进行全面的考虑,正确处理,才能得到符合实际的基准有限元模型。

In order to establish an accurate and reliable baseline finite element model of concrete cable-stayed bridge, modal testing was conducted on a large scale （1 ： 15） concrete cable-stayed test bridge with II shaped cross-section girder. The initial dynamic finite element models of test bridge were established by single beam pattern, triple-girder pattern, beam-shell pattern and solid pattern respectively, and then the initial finite element models were updated by the parameter sensitivity based model updating technology. The calculated values for dynamic characteristics before and after model updating were compared with measured data. The calculation accuracy and the model updating effect of different finite element models were discussed, the error sources of finite element modeling and relevant issues of model updating were analyzed. The results show that the calculation errors of initial finite element models are mainly caused by modeling errors and parameter errors. Beam element models have limitations in modeling. Finite element modeling should take consideration of the structural characteristics and analysis target. Model updating should be combined with experiment and the various factors that cause the finite element model calculation error should be comprehensively considered, then the realistic baseline finite element model can be acquired.