含裂纹损伤箱型梁剩余扭转极限强度研究

Research on the residual ultimate strength of cracked box girder subjected to torsional load

针对含裂纹损伤箱型梁的剩余扭转极限强度问题,通过考虑结构特征及裂纹分布的差异性,基于净截面屈服理论提出更为准确地评估裂纹影响的剩余扭转极限强度简化计算公式,能够很好地反映裂纹损伤所导致的极限强度衰减趋势。利用非线性有限元方法,考虑中心裂纹与边缘裂纹2种裂纹形式,考察结构应力分布的变化与规律,验证扭转载荷下裂纹分布与裂纹尺寸对剩余极限强度的影响。数值计算表明,本文提出的公式具有较好的准确度。

Concerning the residual ultimate strength of box girder subjected to torsional load, the diversity of structure feature and crack distribution is taken into account in this paper. Simplified calculating formulas with better accuracy to estimate the residual ultimate strength are proposed, which could reflect well the reduction tendency of ultimate strength caused by crack damage, based on the theory of net section yield criterion. Using the nonlinear finite element method, the crack forms including the center-crack and edge-crack are considered, and the effect of crack distributions and crack sizes on the residual ultimate strength of box girder is verified by investigating the variety of stress distribution. According to the numerical calculation, the formulas proposed have better accuracy.