混凝土结构等耐久性设计方法

Equal Durability Design Method for Concrete Structure

针对混凝土结构耐久性能不均衡的现象,在混凝土等截面耐久性设计的基础上提出了混凝土结构等耐久性设计方法,并明确了该方法的定义。首先将结构进行分层模块化划分,基于等耐久性原则确定各层次的目标使用寿命,然后进行使用寿命设计,使各层次的耐久性使用寿命达到目标要求;在构件截面层次上,对截面的角部采取措施避免截面角部钢筋提前锈蚀引起耐久性失效,实现截面的等耐久性。提出了结构分层模块化划分的规则和方法及基于等耐久性原则的目标使用寿命确定方法和过程;对于耐久能力严重不足的部位(角部),将钢筋替换为不锈的纤维增强复合材料(FRP)筋,避免过早使耐久性失效,其余部位通过调整保护层厚度使结构达到等耐久性的要求。由于局部环境不同,同种类型的构件需要设置不同的保护层厚度才能实现等耐久性的目标。提出了等耐久性设计的总体过程及不同耐久性等级的使用寿命安全系数取值范围,并通过一个混凝土桥算例说明了截面和结构层次等耐久性设计过程。结果表明:等耐久性设计可以优化选择各类构件的耐久寿命,合理安排初始投资,减少大修次数,降低结构后期维修成本,延长结构寿命,实现混凝土结构的可持续发展。

In view of the phenomenon that the durability of concrete structure was unbalanced,based on the durability design of concrete section,the durability design method of concrete structure was put forward,and the definition of equal durability design method was proposed.The component in concrete structure was classified and the service lives of different types of components were set to achieve the equal durability design method for sections.Firstly,the structure was divided into layers and modules.Based on the principle of equal durability,the target service life of each layer were determined,and then the service life was designed to make the durability service of each layer meet the requirements.At the level of component interface,measures were taken to avoid the durability failure caused by the early corrosion of the reinforcement at the corner of the interface,so as to achieve the equal durability of the section.By using the rules and methods of hierarchical modular division of structure,the method and process of determining the target service life based on the principle of equal durability,the overall process of equal durability design and the range of service life safety factors of different durability levels were proposed.For the corners where the durability was seriously insufficient,the reinforcement was replaced with stainless FRP reinforcement to avoid premature failure of the durability,and the test parts needed to meet the requirements of equal durability by adjusting the thickness of the protective layer.Due to the different local environment,the same type of components needed to set different thickness of protective layer to achieve the goal of equal durability.The process of durability design such as interface and structure level was proved by an example of a concrete bridge.The results show that the durability design can optimize the service life of various components,reasonably arrange the initial investment,reduce the number of overhaul,reduce the maintenance cost in the later stage of the structure,extend the structure life,and realize the sustainable development of concrete structure.