不同高温工况对变形钢筋-混凝土黏结性能影响的细观数值分析  

Mesoscale modelling on effect of temperature conditions on bond behavior between deformed rebar and concrete

作　　者：李潇雅 张仁波[1,2] 金浏 杜修力[1] LI Xiaoya;ZHANG Renbo;JIN Liu;DU Xiuli(The Key Laboratory of Urban Security and Disaster Engineering,Ministry of Education,Beijing University of Technology,Beijing 100124,China;Department of Civil Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]北京工业大学城市与工程安全减灾教育部重点实验室,北京100124 [2]清华大学土木工程系,北京100084

出　　处：《建筑结构学报》2022年第12期300-310,共11页Journal of Building Structures

基　　金：国家自然科学基金项目(51822801,51978022)。

摘　　要：火灾会引起钢筋与混凝土材料力学性能的劣化,从而影响钢筋与混凝土界面的黏结-滑移性能。为研究不同高温工况下变形钢筋与混凝土的黏结性能,建立了考虑混凝土材料非均匀性和带肋钢筋表面特性的三维细观模型。通过拉拔试验模拟验证了细观力学模型的有效性,并分析不同高温工况对黏结性能的影响。结果表明:采用考虑混凝土非均匀性的数值模型,可以更好地观察钢筋与混凝土界面间的黏结破坏机理;相较于高温下的试件,冷却后的试件黏结性能较好;自然冷却和洒水冷却对试件黏结破坏机理、钢筋应力分布和黏结应力-滑移曲线的影响不大;不同高温工况下,黏结强度随温度升高呈线性下降趋势,极限滑移与温度之间表现出非线性增长关系。通过对不同高温工况下黏结强度和滑移的分析,结合经验公式,给出了预测高温下和冷却后黏结性能的计算式,其能较好地描述高温下、自然冷却后和洒水冷却后,变形钢筋与混凝土之间黏结强度和极限滑移随温度的变化。Fire accidents cause deterioration of the mechanical properties of steel and concrete,and thus affect the bond-slip behavior of the interface between them.In order to study the bond behavior between deformed steel bars and concrete at different temperature conditions,a three-dimensional(3 D)mesoscale model was established considering the heterogeneity of concrete and the surface characteristics of deformed steel bars.The validity of the mesoscale model was verified by the pull-out test.Subsequently,the effects of different temperature conditions on the bonding properties were discussed.The results show that the mesoscale model considering the heterogeneity of concrete can better reflect the bond failure mechanism between the interface of rebar and concrete.Compared with the specimen at a high temperature,the bond performance of the specimen after cooling down is better.The effect of the cooling method on the bond failure mechanism,stress distribution of steel bar and bond-slip curve can be ignored.Under different temperature conditions,the bond strength tends to decrease linearly with the increasing temperature,and the ultimate slip shows a non-linear relationship with the temperature.Based on the analysis of bond strength and slip under different high temperature conditions,as well as empirical formulas,the calculation formulas for predicting the bond properties at high temperatures and after cooling were given.The formulas can reflect the change of bond strength and ultimate slip between deformed steel bar and concrete with temperature under different temperature conditions.

关 键 词：变形钢筋 混凝土 温度 细观数值模拟 黏结滑移性能 

分 类 号：TU375[建筑科学—结构工程] TU311.41