悬臂施工阶段大跨径刚构桥稳定性的参数分析

Parametric Analysis on the Stability of Long-Span Rigid-Frame Bridge during Cantilever Construction

针对悬臂施工阶段中大跨径预应力混凝土刚构桥的稳定性问题,依据弹性屈曲理论、挠度理论、弹塑性理论和压溃理论,计算和分析几何非线性、材料非线性、初始几何缺陷以及混凝土材料的压碎、开裂、骨料咬合效应等因素的影响;研究墩身偏斜度、施工荷载形式以及桥墩系梁刚度等参数对悬臂施工阶段大跨径预应力混凝土刚构桥稳定性的影响效应。分析和研究结果表明:混凝土材料的力学特性对大跨径预应力混凝土刚构桥在悬臂施工阶段中的稳定性有明显的影响;结构稳定系数随墩顶初始横向偏位的增加而呈分段二次曲线规律减小;桥墩系梁刚度与结构稳定系数的关系遵循指数曲线规律;非对称形式的施工荷载对悬臂施工阶段大跨径预应力混凝土刚构桥的稳定性更为不利。

Aiming at the stability of long-span prestressed concrete rigid-flame bridge during its cantilever construction, this paper investigates the effects of several dominant factors on the stability by means of the buckling theory, the deflection theory, the elasticity-plasticity theory and the collapse theory. Such factors are geometric nonlinearity, material nonlinearity, geometric imperfection, concrete crush, concrete crack, aggregate interlocking, etc. The effects of the initial pier deflection, the construction load type and the rigidity of tied-beam on the stability of long-span prestressed concrete rigid-frame bridge during cantilever construction phase are discussed in detail. Analysis and study results show that the mechanical characteristics of reinforced concrete have significant impact on the stability of long-span prestressed concrete rigidframe bridge during cantilever construction phase. Structure stability coefficient decreases with the increase of the initial pier deflection according to parabola curves. The relationship between the rigidity of tied-beam and structure stability coefficient is in index curve. The unsymmetrical construction loads is dangerous to the stability of long-span prestressed concrete rigid-frame bridge during cantilever construction phase.