研究目的:多室箱梁在竖向弯曲变形时，对应于初等梁理论纵向应力计算模式，存在多种横向剪力滞效应模式。本文在分析单箱双室箱梁剪力滞效应的基本模式和力学机理的基础上，结合铁路单箱双室简支箱梁算例，研究在跨中集中力和满跨均布荷载下，不同剪力滞效应模式的分布规律。以对剪力滞效应影响较为突出的高跨比为变量，研究高跨比变化对各剪力滞模式的影响规律。
研究结论:通过对双室箱梁的剪力滞效应分析，得出:(1)以双室箱梁为代表的多室箱梁，对应于同一纵向对称荷载，存在着多种剪力滞效应模式，且不同模式的剪力滞效应差异较大;(2)在单箱双室箱梁的多种剪力滞效应模式中，集中力仅作用于中腹板时，截面的剪力滞效应最为突出，同时剪力滞效应对高跨比的改变最为敏感;(3)考虑到多室箱梁剪力滞效应的多模式性，在进行多室箱梁设计时，应充分考虑不同荷载作用模式对剪力滞效应的影响;(4)本文研究方法和结论可为多室箱梁桥的设计和力学分析提供理论借鉴。
Research purposes:When mufti-cell box girder is bending, there are many models of shear lag corresponding to its calculation model of longitudinal stress based on elementary beam theory. On the basis of analyzing the shear lag basic models and mechanical mechanism，shear lag effect of a railway simple supported twin-cell box girder is calculated which applied by concentrated force on mid span and uniform load on full span. With the changing of Height-span ratio，shear lag effect of different load models are discussed.
Research conclusions;(1)For twin-cell box girders，there are more shear lag effect models corresponding to its longitudinal symmetric load model，meanwhile there is much difference between different models.(2)In all shear lag effect models，the most prominent model is concentrated force only applied on mid web. Also，this model is affected by the height-span ratio most obviously.(3)Considering the multiple patterns of shear lag effect，in designing of mufti- cell box girder, the influence of different load models of shear lag effect should be considered fully. ( 4 ) The simulation method and results of this paper have some reference value for design and mechanical analysis of mufti-cell box Girders.
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