摘要
发展了考虑时变温度效应的腐蚀开始时间模型和碳化腐蚀率模型,以混凝土保护层厚度、水灰比以及钢筋直径等参数为设计变量,建立钢筋混凝土(RC)梁桥耐久性设计全寿命概率成本模型。以寿命期内全寿命成本现值最小为优化目标、寿命期基于锈胀开裂的正常使用性能为约束条件,提出大气环境下RC梁桥全寿命耐久性优化设计模型,构建大气环境下RC梁桥基于成本-效益的耐久性参数确定新方法,为大气环境下RC梁桥全寿命过程耐久性设计参数确定提供了新的思路。计算发现RC梁桥的全寿命性能与钢筋的位置和直径有关。对于大气环境条件下受碳化腐蚀的RC梁桥,采用初始成本最优得到的耐久性设计参数不满足全寿命耐久性能要求。综合考虑全寿命成本和性能时,当保护层厚度为30mm和水灰比为0.45时,尽管考虑将来累积碳化腐蚀损伤效应,提高混凝土保护层厚度和混凝土强度不能降低全寿命成本,反而增加初始造价,不是成本效益比最优的耐久性设计对策。
Corrosion initiation model and carbonation-induced corrosion rate model with considered time-dependent temperature effect were developed, and a probabilistic life-cycle cost model was proposed considering the concrete cover thickness, water-cement ratio and rebar diameter as design variables. With the present value of life-cycle cost as the optimized objective and corrosion-induced cracking based serviceability peribrmance as the boundary constraint, a hybrid life-cycle cost optimization model in the atmospheric environment was established for reir,forced concrete （RC） bridges subjected to carbonation-induced corrosion. Consequently, a cost-effective and cost-benefit based determination method of durability parameters ~br RC bridges in the atmospheric environment was given, providing a new path for determining the durability design parameters, it is found that durability performance is related to the position and diameter of reinforcing bar. For RC structures in the atmospheric conditions subjected to carbonation-induced corrosion, the use of minimizing the initial cost may not satisty the requirement of whole life-cycle performance. Considering the whole life- cycle cots and durability performance comprehensively and even though the cumulative carbonation effect may also be included, when the concrete cover thickness is 30mm and W/C ratio is 0.45, increasing concrete cover thickness and concrete compressive strength can not reduce the whole life-cycle cost, instead, it may increase the initial cost. Hence, it is not a cost-effective design scheme.
出处
《土木工程学报》
EI
CSCD
北大核心
2013年第1期69-75,共7页
China Civil Engineering Journal
基金
国家自然科学基金(51008037
51178060)
湖南省自然科学基金(12JJ6050)
湖南省科技计划(2012FJ4124)
关键词
RC桥梁
全寿命耐久性设计
碳化腐蚀
全寿命成本分析方法
时变可靠度
RC bridges
whole life-cycle durability design
carbonation-induced corrosion
whole life-cycle costanalyzing method
time-dependent reliability
