冻融损伤RC梁柱承载与变形能力时变评估模型

Time-dependent evaluation model of load carrying and deformation capacity of frost-damaged RC frame beam-column

为评估严寒地区在役RC框架结构的时变化承载能力与变形能力。该文首先利用最冷月平均气温θ为指标建立实际环境下的年均冻融循环次数F_(act)计算式;进而考虑室内外损伤比例系数S、饱含水时间比例系数k,将F_(act)等效换算为基于“快冻法”的实验室冻融循环次数F_(Q)。同时,以抗压强度为冻损指标,建立可将F_(Q)换算为基于“人工气候”的实验室冻融循环次数F的等效冻融循环次数计算模型。利用已有研究成果建立弯曲破坏未冻融RC梁柱特征状态承载力与变形能力计算式,进而提出可考虑F、f_(c)、n影响的冻融损伤RC框架梁柱特征状态承载力与变形能力计算式。在此基础上,建立冻融损伤RC框架梁柱承载能力与变形能力时变评估模型。研究可为严寒地区在役RC框架结构的冻融劣化时变评估提供参考。

In order to evaluate the time-varying bearing capacity and deformation capacity of in-service RC frame structure in severe cold area.In this paper,the annual average number of freeze-thaw cycles in the actual environment F_(act) is calculated by using the average temperature of the coldest monthθas the index.Furthermore,considering the indoor and outdoor damage ratio coefficient S and the water saturated time ratio coefficient k,the F_(act) is equivalent to the number of laboratory freeze-thaw cycles F_(Q) based on the“quick freezing method”.Simultaneously,taking the compressive strength as the freezing loss index,the calculation model of equivalent freezing and thawing cycles which can convert F_(Q) into laboratory freezing and thawing cycles F based on“artificial climate”is established.Based on the existing research results,the formulas for calculating the characteristic state load carrying capacity and deformation capacity of unfrozen RC beamcolumn under flexure failure are established,and then the formulas for calculating the characteristic state bearing capacity and deformation capacity of frost-damaged RC frame beam-column considering the effects of F,fc and n are proposed.On this basis,the time-dependent evaluation model of bearing capacity and deformation capacity of frozen-thawed damage RC frame beam-column is established,and the time-varying evaluation of freeze-thaw deterioration of RC frame structural members in severe cold area is realized.The research can provide a reference for the time-varying assessment of freeze-thaw deterioration of in-service RC frame structures in severe cold areas.