大跨径预应力混凝土斜拉桥主梁节段模型的研究

STUDY ON SEGMENTAL MODEL OF GIRDER OF LONG-SPAN PRESTRESSED CONCRETE CABLE-STAYED BRIDGE

梁是斜拉桥的关键部位,在轴力、弯矩、剪力和扭矩作用下其受力非常复杂,一般的平面及空间杆系分析很难反映其实际的应力分布。描述分离式双主肋断面主梁斜拉桥的受力特点以及1∶3的主梁节段模型设计和试验方案。在试验研究和空间有限元分析的基础上,给出了在预应力、索力及桥面荷载作用下主梁混凝土的应力分布试验测试值和有限元分析值,得到了主梁节段模型的开裂荷载和极限荷载,并研究了主梁在预应力作用下混凝土桥面板上缘应力的分布及传递角度。本文的研究成果与美国规范相比较偏于安全,可作为该类主梁截面有效分布宽度的计算依据。

Girder is the key part of the cable-stayed bridge where stress distribution is rather complicated under the combination of axial force,moment, shear force a nd torsion moment.A general plane or spatial analysis method is hard to reflect actual stress status of girder.Mechanics features of cable-stayed bridge with d isjunct ∏-type cross section girder,modeling design on a scale of 1∶3 and tes ting program are described. Based on experimental study and spatial finite eleme nt analysis,stress values of the segmental model of girder under action of prest ressing,tension of cable and the service load are presented,while the cracking l oad and ultimate capacity are obtained. In addition, the surface stress distribu tion on concrete deck of prestressed girder and its transmission angles are also analyzed. Compared with the Specifications of AASHTO,represented results tend t o be conservative. According to the analysis above, the effective width of concr ete deck can be calculated.