基于外荷载修正的箱形梁横向内力分析

Transverse internal force analysis on box girder based on external load correction

为了合理计算薄壁箱梁在偏心荷载作用下的横向内力,采用弹性支承梁理论对作用在薄片框架上的外荷载进行修正.根据箱形梁畸变位移与框架位移之间的协调关系,采用满足平衡条件的新计算模型,推导出计算箱形梁横向内力的基本公式,并分析了几何参数对箱形梁横向内力的影响.结果表明,当高宽比小于1.5时,横向弯矩降低幅度较大,且在远离跨中截面处以较快的速度衰减;当高宽比大于1.5时,横向弯矩降低幅度较小,且在箱形梁跨中大部分范围内基本保持不变.与有限元计算结果相比,全梁各横截面计算误差均小于10%.基于修正的外荷载计算所得的箱形梁沿跨度方向的横向弯矩较推广的TYL框架分析法精度更高.

To reasonably calculate the transverse internal force of a thin-walled box girder under the eccentric load,the elastically supported girder theory was used to correct the external load acting on the frame.According to the coordination relationship between the deformation displacement of the box girder and the displacement of the frame,the basic formulas for calculating the transverse internal force of the box girder were derived by using a new calculation model satisfying the equilibrium conditions.The influence of the geometric parameters on the transverse internal force of the box girder was investigated.The results show that when the aspect ratio is less than 1.5,the transverse bending moments decrease obviously,and those away from the middle section of the span decay rapidly.However,when the aspect ratio is higher than 1.5,the decreasing degrees in the transverse bending moments are smaller,and the transverse bending moments remain basically unchanged in the most range of the span of the box girder.Compared with the results of finite element calculation,the calculation error of each cross section of the whole girder is less than 10%.The transverse bending moments calculated based on the modified external load have better accuracy than those by the generalized TYL frame method along the span direction.