近海在役钢筋混凝土框架结构抗震能力时变劣化规律

为量化表征近海在役钢筋混凝土(reinforced concrete,RC)框架结构的抗震能力时变劣化规律,以氯离子扩散理论为基础,首先研究建立了钢筋锈蚀深度预测模型,介绍了近海在役RC框架结构数值建模方法,进而以可抵御的地震峰值加速度(peak ground acceleration,PGA)为指标表征结构的抗震能力,提出了基于能力谱方法的在役RC框架结构抗震能力量化方法,并分析了不同抗震设防水平下近海在役RC框架结构的抗震能力时变劣化规律,建立了相应的量化模型.结果表明:所建立的抗震能力量化方法可以直接量化在役RC框架结构不同破坏极限状态下可抵御的地震强度,从而直观反映近海在役RC框架结构的实际抗震能力;随着服役龄期的增长,近海在役RC框架结构不同破坏极限状态的抗震能力近似呈线性关系退化,且其退化速率随设防水平的降低不断提高;随着设防水平的提高,近海在役RC框架结构抗震能力劣化的起始时间不断提前;所建立的时变抗震能力量化模型可近似表征近海在役RC框架结构抗震能力的时变劣化规律,但尚需实例验证.

Study on time-dependent deterioration of seismic capacity of existing RC frame structure in offshore environment

In order to quantify the time-dependent seismic capacity deterioration law of existing RC frame structures in offshore environment, based on the chloride diffusion theory, a prediction model for the corrosion depth of reinforcement was firstly studied and established, and the numerical simulation method of existing RC frame structure is introduced. Then, the seismic capability of existing RC frame structures is characterized by PGA which represents the earthquake intensity of the structure can resist, and a method for quantifying the seismic capability of existing RC frame structures is proposed, which is based on the capability spectrum method. Based on this, the time-dependent deterioration law of seismic capacity of existing RC frame structures with different fortification levels is analyzed, and the corresponding prediction model is established. The results show that the seismic capacity quantification method established in this paper can directly quantify the earthquake intensity that the existing RC frame structures can bear under different failure limit states, and directly reflect its actual seismic capacity. With the increasing of service age, the seismic capacity of existing RC frame structures at different failure limit states degenerates linearly, and the degradation rate increases with the decrease of the level of fortification. With the improvement of the level of fortification, the onset time of seismic capacity degradation of existing RC frame structures keep advancing. The established time-dependent seismic capability prediction model can approximately characterize the law of seismic capability degradation of existing RC frame structures in offshore environment, but it needs to be implemented Example verification.