大悬臂展翅预应力混凝土宽箱梁桥极限承载力分析

摘要

To study the ultimate bearing capacity of the large cantilever structure,an accurate space finite ele-ment model was built for numerical analysis with the background of a prestressed concrete box -girder bridge with large -cantilevev -wing.Taking into account of the geometric nonlinearity and the material nonlinearity, the structure ultimate bearing capacity and the distribution regularity of cracks under three load cases(eccentric concentrated load,symmetrical concentrated load and uniform distributed load)were analyzed.It is concluded that the structure ultimate bearing capacity under the load case of symmetrical load is larger than that under the case of asymmetrical load;the distributions of the stress and cracks under the load case of asymmetrical load are also asymmetrical and cracks are more likely to appear in the root of the cantilever wing.The stress condition of side span is worse than mid -span under uniformly distributed load.%针对大悬臂展翅结构的极限承载能力问题，以某大悬臂展翅预应力混凝土宽箱梁桥为实际工程背景，建立精细的空间有限元模型进行数值分析。考虑结构几何非线性和材料非线性，研究偏心集中荷载、对称集中荷载、均布荷载3种工况作用下，结构的极限承载能力及裂缝的分布规律。结果表明，对称加载形式的极限承载能力大于非对称加载形式的极限承载能力；非对称荷载作用下，桥梁应力及裂缝分布也具有较大非对称性，且悬臂板根部更加容易出现裂缝，均布荷载作用下，桥梁边跨应力状况劣于中跨。