基于新型广义位移的箱形梁剪力滞分析

与已有文献中采用的广义位移不同,选取剪力滞引起的附加挠度作为广义位移,在构造广义翘曲位移函数的基础上,提出了一种分析箱梁剪力滞的解析法.基于能量变分法建立控制微分方程,并导出了简支箱梁的附加挠度和广义力矩计算公式.通过对一个混凝土简支箱梁算例的计算表明,按本文方法计算的跨中截面应力与有限元法的结果很接近,从而验证了方法的正确性.研究结果表明,剪力滞引起的混凝土简支箱梁跨中截面的附加挠度很小,工程实践中可以忽略不计,但是,跨中截面的剪力滞翘曲应力达到初等梁应力的11.4%,工程实践中不能忽略.

Shear Lag Analysis of Thin-walled Box Girders Based on a New Generalized Displacement

Differing from the generalized displacement used in existing references,the additional de-flection induced by shear lag is adopted as generalized displacement for analyzing shear lag of box girders.Based on the generalized warping displacement function defined,an analytic method for analyzing shear lag is proposed.The governing differential equation is established by applying en-ergy calculus and the formulas of the additional deflection and generalized moment for simply sup-ported box girder are derived.An example of simply supported concrete box girder is analyzed and the calculated stress results at mid-span cross section are very close to those by finite element method,validating the present analytic method.It is shown that the additional deflection at the mid-span cross section of the simply supported concrete box girder is very small and thus can be ignored in engineering practice.However,the shear lag warping stress at the mid-span cross sec-tion reaches 1 1 .4% of the ordinary beam stress,which should not be ignored in engineering prac-tice.