双薄壁墩连续刚构桥基频的统一计算模式

Uniform calculation pattern for fundamental vibration frequency of continuous rigid frame bridge with double-thin-wall piers

为研究双薄壁墩连续刚构桥基频计算公式并建立其统一表达式,基于能量原理在给出振型函数的基础上提出了高墩连续刚构桥基频的一般表达式;以典型高墩连续刚构桥梁为例,通过改变系梁的数量、位置、刚度,构造了多种不同的桥梁结构形式,建立了相应的有限元分析模型,研究了系梁设计参数对桥梁结构自振特性影响的一般规律,分析了具有系梁构造的高墩大跨连续刚构桥基频理论计算公式,并对高墩连续刚构桥基频的一般表达式进行了修正,给出了基频的统一计算模式,最后对该模式的可行性进行了实桥验证。结果表明:设置系梁后,连续刚构桥的基频至少增大了15%;随着系梁与桥墩刚度比值的增大,高墩连续刚构桥基频明显增大,两者呈一定的函数关系;本文提出的基频统一公式计算值与桥梁基频实测值误差为3%。研究成果可为此类桥梁抗震设计及结构评估提供参考。

In order to obtain the fundamental vibration frequency of the continuous rigid frame bridge with double-thin-wall and its uniform calculation function, firstly, the general fundamental vibration frequency is presented by giving vibration mode shape based on energy principle. A typical continuous rigid frame bridge with high piers is taken as an example, and plenty of similar bridges are fabricated by changing the number, the location and the stiffness of tie beams, respectively, then corresponding finite element(FE) models are set up to study the effect of tie beams on general vibration characteristic of the bridge structures. Then, the structural fundamental frequency is regressed and the general fundamental vibration frequency function is modified, namely, the uniform calculation function is obtained. Finally, the presented theoretical formula of fundamental frequency is validated by the practical measurement. Results obtained indicate that the fundamental vibration frequency of the continuous rigid frame bridge increases at least 15% after the tie beams are built, and the frequency also obviously increases with the stiffness ratio of tie beam to the pier, and the results also show that the presented uniform fundamental vibration frequency has an error of 3% compared with the measured results. Present research may provide reference to the seismic design and structural assessment of the rigid frame bridges.