斜拉桥斜拉索有限元模拟方法的比较

Comparative Study on Finite Element Simulation Methods for Stay Cables of Cable-stayed Bridges

模拟斜拉索的单元主要有Ernst公式修正弹性模量的杆单元和悬链线单元。后者是非线性单元,比前者计算精度更高,但计算效率稍低。为了能够兼顾精度和效率,以浩吉(浩勒报吉—吉安)铁路洞庭湖特大桥主桥为对象建立有限元模型,对比分析2种单元的内力、刚度和不同工况的计算结果。结果表明:斜拉索应力越小,索越长,2种单元的张拉力角度越大,但单元刚度相差不大;斜拉索应力越小,斜拉索应力变化引起斜拉索刚度的变化越大。施工过程中斜拉索应力较小或变化较大时,建议采用悬链线单元模拟斜拉索;斜拉桥成桥后采用Ernst公式修正弹性模量的杆单元能够得到精度较高的结果。

The main elements for simulating stay cables are the bar element with modified elastic modulus by Ernst formula and the catenary element.The latter is a non-linear element,which can simulate the stay cable accurately,and has higher calculation accuracy than the former,but its calculation efficiency is slightly lower.In order to give consideration to both accuracy and efficiency,the main bridge of Dongting Lake super large bridge on Haolebaoji-Ji’an railway was taken as the object to establish the finite element model,the internal force,stiffness and calculation results of different working conditions of the two elements were compared and analyzed.The results show that the smaller the cable stress and the longer the cable,the larger the tension angle of the two elements,but the difference of element stiffness is small.The smaller the cable stress is,the larger the change of cable stiffness caused by the change of cable stress is.When the cable stress is small or the change is large in the construction process,the catenary element is recommended to simulate the cable.After the completion of the cable-stayed bridge,the bar element with modified elastic modulus by Ernst formula can get high accuracy results.