预应力混凝土斜拉桥施工过程中的收缩徐变效应

Shrinkage and Creep of Prestressed Concrete Cable-stayed Bridge in Construction

针对预应力混凝土斜拉桥施工过程中复杂的收缩徐变效应,运用按龄期调整的有效模量法进行分析,并根据线性徐变理论将混凝土的收缩徐变效应转化为等效节点荷载。分析过程中考虑预应力损失及普通钢筋的影响,其中钢筋的影响通过极限平衡法进行计算。根据该方法编制斜拉桥施工阶段分析的计算程序,通过一片预应力混凝土梁的徐变试验对该方法进行验证,结合荷麻溪大桥实际工程进行分析。针对荷麻溪大桥施工过程中部分断面的高程及应力变化进行分析。分析结果表明:程序计算结果与施工监控实测值吻合较好,验证了该方法的有效性及可靠性。

Due to the complicated effect of shrinkage and creep in construction of prestressed concrete cablestayed bridges,the age-adjusted effective modulus method was applied for analysis. The effect of shrinkage and creep was translated into equivalent node loads by the linear creep theory. Losses of prestresses and effects of regular reinforcement were considered in the analysis process, and the effects of reinforcement were calculated with the limit equilibrium method. The calculation procedure was programmed with the above-mentioned method for analysis on construction of cable-stayed bridges. Verification was made by conducting a creep experiment of a pretressed concrete beam. Then,referring to the construction project of the Hemaxi Bridge, elevations and stresses of some sections were analyzed, and the measured results agreed well with the program analysis values. The proposed method is proved effective and reliable.