混凝土斜拉桥主梁剪力滞研究

Study on Shear Lag for Main Girders of Concrete Cable Stayed Bridges

针对处于压弯状态的混凝土斜拉桥主梁剪力滞效应问题,从新的角度指出剪力滞系数是弯矩和轴力分别产生的剪力滞系数的叠加,其大小与断面所受的弯矩与轴力的比值有关,并给出了剪力滞系数随弯矩轴力比变化的分布规律。采用平面与空间分析相结合的方法,研究了漂浮体系混凝土斜拉桥主梁剪力滞系数分布规律,指出:主梁剪力滞系数主要受轴力影响,并随着轴力的增大而趋于1;当活载弯矩占总弯矩的比例较大时,总剪力滞系数将向弯矩剪力滞系数靠拢,由此导致主梁不均匀应力将很大,设计时应引起注意。

In allusion to the problem of shear lag for main girders of concrete cable stayed bridges under bending and compressing, it is pointed out that the shear lag coefficient is superposed of moment shear lag and axial force shear lag. The value of shear lag coefficient is related to the ratio of moment and axial force. The alterative law of shear lag coefficient with the change of ratio of moment and axial force is presented. The shear lag distributing law on main girders of concrete cable stayed bridges of floating system is studied. It is pointed out that the shear lag coefficient is mainly affected by the axial force and approachs to one with the increase of axial force. When the proportion of live load moment and total load moment is large, the total shear lag coefficient will approach to moment shear lag coefficient. The inequable stress of girder will be large. It should be considered in the design.