Diaphragm Effects on Ultimate Strength of Horizontally Curved Thin-Walled Box Girders.

1.提出了采用中间横隔板加劲的平面曲线焊接薄壁钢箱梁极限强度和非线性行为的分析方法。在非线性有限元分析中，考虑了有限变形、材料在弯曲和圣维南扭转联合作用下的屈服、应变反转引起的卸荷、屈服、卸荷区和再加载区在截面和边沿的扩展以及焊接残余应力的影响。提出了在非线性弯曲分析中如何考虑构件板的局部屈曲和变形翘曲。2.极限强度的分析结果与试验结果的比较令人满意。3.提出的考虑板屈曲的应力-应变曲线模型可以评估构件板的局部屈曲，如图3所示，该模型可以并入…4.屈曲板的宽度可以取为梁截面受压翼缘的宽度，等于腹板受压区的深度。5.本构模型预测的局部屈曲与试验结果吻合得很好。6.在非线性弯曲分析中，变形翘曲的影响可以在初始应变状态下以增量的方式模拟，其中变形翘曲的应变增量是逐步施加的，直到达到外部变形力矩。7.从较低的加载水平，试验证实，受压部位腹板的弯曲变形为凹凸变形。这种现象可以认为是曲线梁中的受压截面部分表现为具有初始弯曲的柱的非线性行为。上述结论中的模型试验结果是基于有限的试验工作。显然，需要对大量模型试验的试验方案进行研究。虽然考虑局部屈曲的本构模型适用于水平和/或竖直加劲梁，但假定的屈曲宽度一般是保守的。较少

1.An analytical procedure is proposed to predict ultimate strength and nonlinear behavior of thin-walled, welded steel box-girder curved in plan and stiffened by intermediate interia diaphragms. In the approach, the effects of finite deformation, yielding of material under combined bending and St. Venant's torsioning, unloading caused by strain reversal, spreads of yielding, unloading and reloading zones in the cross-sections and along the gider, and residual stress due to welding are all taken into account in flexure analysis by nonlinear finite element method. How to consider local buckling of component plates and distortional warping in the nonlinear flexure analysis is also proposed.2.The comparison of the analytical with the experimental results on the ultimate strength was judged satisfactory.3.The local buckling of component plates can be evaluated by the proposed model of stress-strain curve allowing for plate buckling as shown in Fig. 3 and this model can be incorporated into … More the nonlinear flexure analysis.4.The breadth of buckling plate can be taken to be width of the compressive flanges of the cross-section of the girder and equal to the depth of the compressive zone of the web plate.5.The constitutive model predicted the local buckling compared well with the experimental results.6.The effect of distortional warping can be simulated in an incremental way at the initial strain-state in the nonlinear flexure analysis, where the strain increments for distortional warping are applied in a step-by-step procedure until an external distortional moment is reached.7.From lower level of loading, bowing deformation which is characterized by covnex form was experimentally confirmed at the compressive part web plate. This phenomenon might be considered to be that the cross-sectional part in compression in the curved girder acts as so-called nonlinear behavior of column with initial crookedness.The above results on the model tests in the conclusions are based on a limited amount of experimental work. Research is clearly needed on the experimental program of larger amount of the model-tests. Though some verification is necessary if the proposed constitutive models allowing for local plate-buckling is to be applied to the girder also stiffened by horizontal and/or vertical stiffeners, the assumed breadth of buckling plate is generally conservative. Less