基于可靠度的混凝土梁耐久性优化设计

Reliability-based optimum design for durability of concrete beams

传统的钢筋混凝土结构优化设计几乎不考虑结构耐久性的要求.本文对允许钢筋部分锈蚀的混凝土梁构件,根据结构安全、适用、耐久三方面的要求,建立了基于可靠度的耐久性优化模型,并利用遗传算法对其进行优化计算.研究发现结构耐久性与气候、使用环境及养护时间有关,提高混凝土强度等级和保护层厚度可以改善结构的耐久性.估算失效费用对结构总成本和优化策略有很大影响,当失效费用较低时,宜通过增加保护层厚度来保证结构的耐久性;当失效费用较大时,采用高强度混凝土比较经济.

Durability was hardly considered in traditional optimum design of RC (reinforced concrete) structures. This paper presents a reliability-based optimum model of reinforced concrete beam with limited corrosion by carbonization according to the requirements of safety, serviceability and durability. The design parameters were optimized by GA (genetic algorithm). The following conclusions were obtained: the structure's durability is influenced by climate, service condition and curing time. The use of higher concrete grade or deeper cover depth enhances the durability of RC structures. The total cost is greatly dependent on the estimated failure cost. If the failure cost is estimated to be low, it is better to use the maximum allowable concrete cover depth to ensure the durability; if the failure cost is estimated to be high, the application of high-grade concrete is more economical.