小矢跨比上承式钢提篮拱桥动力及稳定性分析

Dynamic Characteristic and Stability Analysis of Small Rise-Span Ratio Steel Deck-Type Basket Arch Bridge

目的研究小矢跨比上承式钢提篮拱桥的动力特性、稳定性能影响因素及其变化趋势.方法以某上承式钢提篮拱桥为背景,采用有限元软件ABAQUS建立空间有限元模型,模型中对拱肋、主梁、边墩及立柱均采用梁单元建模,桥面板采用壳单元建模.通过改变模型的矢跨比和内倾角,分析其对拱桥自振周期、振型、屈曲稳定系数的影响.结果矢跨比对拱桥自振周期及稳定系数影响较大,随着矢跨比减小,拱桥面外一阶稳定系数先增大后减小;内倾角对此类拱桥的一阶、二阶自振周期和面外稳定系数影响较大,当内倾角α<4°,一阶振动的周期随着内倾角α的增加而减小,当内倾角α>4°,随着内倾角α的增加,二阶振动的周期逐渐减小,增大内倾角面外稳定性提高.结论得到的不同内倾角和矢跨比下拱桥动力特性和稳定性的变化规律,可为此类拱桥的设计和工程实践提供参考和借鉴.

In order to study the influence factors and the changing trend of the dynamic characteristics and the stability of the small rise-span ratio steel deck-type basket arch bridge,a 3-D FE model was established based on a similar steel arch bridge by finite element software ABAQUS.In the model,the arch rib,girder,side pier and column are modeled by beam element,and the deck is modeled by shell element.By changing the rise-span ratio and inner lean angle of the model,the influence of its naturally period,vibration mode and buckling stability coefficient of the arch bridge is studied.The results show that,the natural period and the stability coefficient of the arch bridge are largely influenced by the rise-span ratio.With the decrease of the rise-span ratio,the first order stability coefficient of the arch bridge increases first and then decreases.The inner lean angle of the bridge has a greater influence on the first and second order of natural vibration period.When the angle of alpha is less than 4°,the first-order natural vibration period decreases with the increase of alpha,and when the angle of alpha is more than 4°,along with the increase of the angle alpha,the period of the second-order natural vibration period decreases.By increasing the arch rib in the lean angle,the lateral stability performance is significantly improved.The dynamic characteristics and stability of arch bridges with different inner-lean angle and rise-span ratio is obtained,which has certain reference value for the design and engineering practice of such arch bridges.