曲箱梁考虑剪力滞效应的弯扭耦合分析

本文以薄壁曲梁理论为基础 ,建立了薄壁曲线箱形梁考虑剪力滞效应的控制微分方程 ,提出了用样条有限点法 (SFPM)分析薄壁曲线箱形梁剪力滞问题。考虑曲线箱梁的弯曲、扭转、翘曲和剪力滞效应等 ,以位移v ,w和θ作为基本未知量 ,采用三次B样条函数作为位移插值函数 ,从最小势能原理出发 ,建立了样条离散化的刚度方程。推出了精确的刚度矩阵显式 ,并编制了相应的计算程序。样条有限点法将三维箱梁弯曲问题简化为一维问题 ,由于样条函数具有很好的光滑性 ,因而此方法能以极少的未知量得到较高的精度。文中给出了典型的计算实例 ,还分析了曲率半径及荷载形式对剪力滞效应的影响。

曲箱梁桥考虑翘曲和剪滞效应的弯扭耦合变形分析

在分析曲箱梁桥弯扭耦合变形时考虑了翘曲和剪滞 效应。通过对普通曲梁增加节点位移未知量，在流动的圆柱极坐标 系下，导出了平面曲线薄壁箱梁的单元刚度矩阵。给出了算例。

钢结构人行天桥曲箱梁中横隔板设置间距的有限元分析

在曲箱梁中设置横隔板,可以改善箱梁受力性能,但设置过密横隔板会增加箱梁自重。因此确定横隔板设置间距至关重要。从横隔板设置间距对截面及腹板变形和应力分布的影响分析,确定横隔板的适当设置间距,供有关设计使用。

松江立交改建工程圆曲箱梁吊装技术

于1998年底建成的沪杭高速公路通车4年来,车流量以年平均15%的速度增长,目前日均全程流量已超过2.7万辆,是全国重交通条件下最繁忙的高速公路之一.因此,为适应交通需求和解决松江新城同高速公路的互通,于去年7月对松江立交进行改建,经11个月的建设,新建NE、WN两条总长760m的匝道高架桥梁结构已贯通,改建的ES、EN、SE、WS等4条总长620m的地面匝道也即将完成.这次改建工程是在保持高速公路正常通行的情况下进行的,因而施工难度较大.本文仅就其中30m圆曲箱梁的吊装技术介绍如下.

“S”形曲线混凝土连续箱梁受力性能分析

由于"S"形曲线混凝土连续箱梁具有能够克服特殊地形地貌限制、线形优美、节约土地、改善行车性能等优点,因而在高速公路和城市立交工程中得到广泛应用。以福州市新店外环路西段道路工程上一座"S"形曲箱梁桥为工程背景,采用有限元软件ANSYS建立实体模型,分析了"S"形曲箱梁横向剪力滞效应分布规律、曲率半径对"S"形曲箱梁支反力和自振频率的影响,计算结果表明:"S"形曲箱梁随着曲率半径的减小,内侧支座处的反力会逐渐减小,甚至出现负反力;"S"形曲箱梁1到5阶自振频率随着曲率半径由200 m增大至800 m,自振频率呈现出先减小后增大的趋势。

Lateral-torsional buckling of box beam with corrugated steel webs

Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.

Study on the Mechanical Properties of Irregular Curved Steel Box Girder for City Viaduct

This paper deeply analyses the influence of different local tectonic on stress performance of spatial curved steel box Girder Bridge, using the finite element analysis software to establish space finite element model of this bridge, calculation and analysis were made on the bridge of the strength, stiffness. It has certain reference value for guiding engineering design, have a good foundation for the mechanical properties and stability of linear and nonlinear further study of curved steel box girder.

Distortional buckling analysis of steel-concrete composite box beams considering effect of stud rotational restraint under hogging moment

Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are essential factors affecting SCCBB distortional buckling.Based on the stationary potential energy principle,the analytical expressions for the rotational restraint stiffness(RRS)of the web upper edge as well as the RRS and the lateral restraint stiffness(LRS)of the bottom plate were derived.Also,the SCCBB critical moment formula under the hogging moment was derived.Using twenty specimens,the theoretical calculation method is compared with the finite-element method.Results indicate that the theoretical calculation method can effectively and accurately reflect the restraint effect of the studs,top steel flange,and other factors on the bottom plate.Both the RRS and the LRS have a nonlinear coupling relationship with the external loads and the RRS of the web’s upper edge.Under the hogging moment,the RRS of the web upper edge has a certain influence on the SCCBB distortional buckling critical moment.With increasing RRS of the web upper edge,the SCCBB critical moment increases at first and then tends to be stable.

Dynamic Bayesian identification of mechanical parameters of multi-cell curve box girder based on conjugate gradient theory

For multi-cell curve box girder, the finite strip governing equation was derived on the basis of Novozhilov theory and orthogonal property of harmonious function series. Dynamic Bayesian error function of mechanical parameters of multi-cell curve box girder was achieved with Bayesian statistical theory. The corresponding formulas of dynamic Bayesian expectation and variance were obtained. After the one-dimensional optimization search method for the automatic determination of step length of the mechanical parameter was put forward, the optimization identification calculative formulas were also obtained by adopting conjugate gradient method. Then the steps of dynamic Bayesian identification of mechanical parameters of multi-cell curve box girder were stated in detail. Through analysis of a classic example, the dynamic Bayesian identification processes of mechanical parameters are steadily convergent to the true values, which proves that dynamic Bayesian theory and conjugate gradient theory are suitable for the identification calculation and the compiled procedure is correct. It is of significance that the foreknown information of mechanical parameters should be set with reliable practical engineering experiences instead of arbitrary selection.