裂缝控制宽度对氯盐侵蚀环境中钢筋混凝土受弯构件劣化及维护成本的影响

Impact of crack control width on degradation and maintenance cost of flexural reinforced concrete members in chloride environment

裂缝控制宽度是保证钢筋混凝土构件在正常工作状态下耐久性的重要参数,该文研究了不同设计裂缝控制宽度对钢筋混凝土构件在使用期的维护成本的影响。首先,在已有研究的基础上提出钢筋混凝土构件开裂区的氯离子扩散系数模型、采用规范的最大裂缝宽度模型、建立构件使用期的维护成本模型。然后,针对港口工程中典型浪溅区的钢筋混凝土受弯构件,采用钢筋脱钝的耐久性极限状态,利用Monte-Carlo方法计算构件的耐久性失效概率,定量分析了裂缝控制宽度对构件劣化及使用期内维护成本的影响。结果表明,裂缝宽度明显影响构件的耐久性失效概率,进而影响构件使用期的维护次数和维护成本;当裂缝控制宽度小于0.3mm时,其对维护成本的影响较小;当裂缝宽度超过0.3mm时,构件维护成本增加迅速。

Crack control width is a key parameter for long-term durability of reinforced concrete （RC） members in service state. This study investigates the impact of crack control width in design phase on the maintenance cost of RC members. For this purpose, a chloride diffusion model for crack zones of RC members is firstly established, the maximum crack width model from design codes is adopted, and the cost models for maintenance of RC members are then proposed. Some typical RC flexural members in port structures are exposed to marine splash zones. Based on the detailed sectional design and the durability limit state of steel depassivation, Monte-Carlo simulation is used to calculate the failure probability of durability for RC members and the relative maintenance costs are evaluated for different crack control width. Results show that, the control width has significant impact on the deterioration process as well as the maintenance cost. For the RC members studied, the maintenance cost is less sensitive to crack with when crack width is below O. 3ram, while it augments substantially when crack width is larger than 0. 3mm.