寿命期内钢筋混凝土连续梁退化过程分析

Analysis of the degradation process for a reinforced concrete continuous girder bridge in life-cycle

摘要:

为实现寿命期内混凝土桥梁退化过程定量分析的目标,在给出退化全过程中3个关键时刻的计算数学模型以及特有力学问题模拟方法的基础上,建立基于有限元数值模拟的混凝土桥梁退化过程分析方法.在理论分析的基础上利用FORTRAN 95编写了分析程序CBDAS,以一座钢筋混凝土连续梁为对象,研究其在氯离子侵蚀作用时给定寿命期内桥梁结构整体力学性能的演变规律.结果表明:氯离子侵蚀作用时,普通钢筋具有开始锈蚀时间早、锈蚀速率快的特点;成桥80 a后,模型梁2个关键截面处的抗弯承载力均小于对应的包络弯矩.对于钢筋混凝土桥梁,其承载能力极限状态时可能会出现耐久性不足.

Abstract:

For the purpose of the degradation assessment of concrete bridges in life-cycle,a finite element-based methodology for the degradation process of concrete bridges is proposed.This is done by:(a) the computation formulas of the three critical times;and(b) the simulation methods of several special mechanics problems in the degradation process.Based on the theoretical analysis,a program named CBDAS is written in FORTRAN 95.The research on the variation of structural performance in given service life with chloride penetration is carried out by means of a reinforced concrete continuous girder bridge.The results show that: the initiation time of reinforcement corrosion is early and the corrosion rate is fast with chloride penetration.In 80 years after structure completion,bending capacities are smaller than the relative envelope moments at two critical sections for the ultimate limit state.As a result,as for the reinforced concrete bridges,the ultimate limit states are more likely to have durability defects.