弯扭耦合下曲线混凝土箱梁截面应力状态的受力机理分析

曲线箱形梁兼具弯梁桥与箱形梁两者的特点,由于曲率的影响,竖向荷载作用下曲线箱梁弯矩与扭矩互相耦合同时存在。根据国内外既有研究成果,对曲线箱形梁空间受力特点及影响因素进行了总结。以60m单跨单箱形截面曲线混凝土简支梁为例,利用有限元软件TDV建立空间板单元模型,分析自重作用下,不同曲线半径下主梁截面正应力及剪应力分布,根据弯曲变形与应变的关系,比较曲线梁桥与直线梁桥正应力横向分布规律,提出用应力增大系数来表征曲线内外侧弧长不同引起的应力变化。研究结果表明,除了受剪力滞后效应影响,曲线箱梁桥截面正应力分布还与内外侧弧长不等引起的应力增大系数有关。

Analysis of Stress Mechanism of Cross Section of Curved PC Box Girder Under the Action of Bending-Torsion Coupling

Curved box girder has both characters of curved girder and box girder,and the coupling effect between bending moment and torsion moment caused by the curvature under vertical load should be taken into account.Based on research results of curved girder at home and abroad,the spatial mechanical characters and influencing factors of curved box girder were summarized in this thesis.Choosing a 60m single-span curved PC simply supported girder with single cell boxed cross-section as the example,spatial plate element models were established by TDV finite element software.Then the distributions of normal stress and shear stress of cross-section of main girder with different curve radius under the action of dead load were analyzed.Afterwards,according to the relationship between bending deformation and strains,and by comparing the transverse distributions of normal stress of curved bridge with that of straight bridge,the thesis put forward a view point that the stress variation caused by the arc length difference between the internal arc and external arc of the curve can be expressed by a magnification coefficient.Analysis results show that,except the effect of shear lag,the distributions of normal stress of cross-section of curved bridge is correlated with the stress magnification coefficient which is caused by the arc length difference between internal arc and external of the curve.