选取二次抛物线作为剪力滞翘曲位移函数,用能量变分法导出双室箱梁剪力滞控制微分方程.通过分别建立单元两端支点处和梁轴处位移之间的变换关系,考虑弯曲、约束扭转及剪力滞变形之间的耦合关系,提出一种适用于斜交支承连续箱梁剪力滞效应分析的梁段单元.对一斜交支承3跨连续双室箱梁模型的计算值与ANSYS壳单元计算值和实测值均吻合良好,证明该单元是可靠的.详细分析斜交支承角度变化对斜交支承3跨连续箱梁剪力滞效应及内力分布的影响,结果表明:与常规支承箱梁相比,斜交支承箱梁的剪力滞效应更为显著；控制截面的弯矩和剪滞力矩均随着斜交支承角度增大而减小,但双力矩却随斜交支承角度增大而增大；荷载横向作用位置对双力矩的分布有显著影响；剪力滞和约束扭转引起的翘曲应力在总应力中占较大比例,设计中必须认真对待.%The quadratic parabola was chosen as the displacement function of shear lag warping of the twin-cell box girder and the governing differential equation for shear lag of the twin-cell box girder was derived by applying the energy variation method. Through establishing the element displacement transformation between the support points and the beam axis at two ends, considering coupling of the bending, restraint torsion and shear lag, the finite segment element was proposed for analyzing shear lag effect of the skewly-supported continuous box girder. A three-span continuous twin-cell box girder model with skew supports was analyzed and its calculated results were in good agreement with the ANSYS shell element results and the measured results , thus validating the proposed segment element. The influence of the variation of skew support angles on the shear lag effect and internal force distribution of the skewly-supported three-span continuous box girder was analyzed in detail. The results show as follows: The shear lag effect in the skewly-supported box girder is more remarkable as compared with the regularly-supported box girder; the bending moment and shear lag moment of key sections decrease whereas the bi-moment increases with increasing of the size of the skew support angle; the transverse position of loading greatly affects the distribution of the bi-moment; the percentage of warping stresses induced by shear lag and restraint torsion is great out of the total stress, which should be treated seriously in design practice.
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