【作者】 李燕；

【导师】 吕彭民；

【作者基本信息】 长安大学 ， 机械设计及理论， 2013， 硕士

【摘要】 为了能对斜拉桥钢锚箱结构强度进行详细的理论研究，本文以某长江公路大桥采用的钢锚箱结构形式为研究对象，针对承受索力最大的SZ28梁段钢锚箱，采用ANSYS软件中的子模型技术法，对其进行了详细的有限元计算和相关分析。计算发现钢锚箱上应力集中严重，尤其是当钢锚箱结构不合理时，如加筋方式不合适或者板件构造不合理，会导致较高的应力集中，使得钢锚箱上应力传递不均匀，应力数值超出其容许值。虽然改进后钢锚箱结构应力集中程度有所降低，各应力值均在其容许范围内，但由钢锚箱的传力机理可知，并不能完全消除钢锚箱上应力集中的现象，因此在钢锚箱服役过程中应对其加强监控。分析发现钢锚箱上索力的传递主要以压应力的方式传递，钢锚箱上各筋板的压应力数值偏大。索力在钢锚箱主焊缝上主要以剪力的形式传递，由局部弯矩作用产生的拉力（压力）数值则较小。但是，钢锚箱竖向尺寸较大，加上局部结构突变，在局部弯矩作用下较小的拉力在钢锚箱底部与外腹板连接处产生较大的局部拉应力，较小的压力在钢锚箱顶端与外腹板连接处产生较大的局部压应力。用国际焊接协会和各船级社推荐的名义应力法和热点应力法，计算钢锚箱在车辆动载荷作用下的应力幅值，发现虽然钢锚箱在恒定载荷作用下应力数值较大，但其动应力幅值均在各规范的容许范围内，说明钢锚箱受车辆动载荷的影响较小。本文中用子模型技术法对钢锚箱结构进行有限元计算，针对改进后钢锚箱结构，将子模型技术法得到的计算结果与传统的等效板厚法和非线性接触法做了详细的比较，得到用子模型技术对索梁锚固区及钢锚箱进行有限元计算时的优越性，即用子模型技术法不仅在模型处理方面难度有所降低，而且计算结果更加准确，尤其是文中采用的壳到体的子模型技术，还能反映板件的厚度效应，是大型复杂构件中局部小尺寸结构分析计算的有效方法。更多还原

【Abstract】 In order to make theoretical research in strength of steel anchor box structure on a cable stayed bridge,detailed finite element calculation and related analysis are made in this paper using the sub-modelingmethod of ANSYS software, which take the steel anchor box over the maximal cable force in SZ28beamfrom one Yangtze River Bridge for example.The results find that there are stress concentrations on steel anchor box, which lead to the no uniformstress transform and over-admission-stress valve, especially when the structure of the steel anchor box isnot reasonable, such as the unreasonable way of plate layout and the inappropriate plate structure. Throughthe stress concentration is reduced sharply and all the stresses are within the admission after the structureimprovement, the situation can and will not disappear according to the theory of cable force transformation.Therefore monitoring is needed when the steel anchor box is working. The calculation shows the cableforce is transformed in the way of pressure stress in the steel anchor box and that the pressure stress valveis a bit higher in each plate of the steel anchor box. Meanwhile the cable force is transformed in the mainwelding line as shear force primarily and tensile force (pressure force) secondary, the latter results from thelocal bending moment of the eccentric cable force. But because of the large vertical seize of the steelanchor box and the local structure break, the small tensile force result in high tensile stress at the bottom ofcombination between the anchor box and the web plate of the beam, and the small pressure force result inhigh pressure stress at the top of combination between the anchor box and the web plate of the beam. Thecalculation of the stress amplitude because of the vehicle dynamic load using the nominal stress and hotstress recommended by International Institute of Welding (IIW) and classification societies shows that thefatigue stress amplitude of the steel anchor box is within the admission valve recommended by standards,which means that the vehicle dynamic load can affect less on the steel anchor box.Aiming at the improvement steel anchor box structure, the advantage of sub-modeling method isobtained by comparing the results of sub-modeling method, traditional equivalent plate thickness methodand the nonlinear contact method, which can be concluded as follows: the lower difficulty of modeling andmore accurate of the result, especially the shell-to-solid skill used in this paper, which can reflect thethickness effect of each plate. Therefore sub-modeling method is an effective way in analysis andcalculating the local small size structure of big complex structure.更多还原