钢筋煤矸石混凝土黏结性能试验研究与数值模拟

Experimental study and numerical simulation on bond performance of reinforced coal gangue concrete

摘要:

为研究带肋钢筋与煤矸石混凝土之间的黏结滑移性能,本文以煤矸石取代率、混凝土强度等级和钢筋直径为变量,设计并制备了36个立方体试件,并进行了中心拔出试验。试验结果表明:随着煤矸石取代率的增加,试件的黏结强度逐渐降低,破坏模式由拔出破坏转变为劈裂破坏；随着钢筋直径的增大,试件的黏结强度呈下降趋势,且煤矸石混凝土的下降幅度较普通混凝土更为显著；随着混凝土强度等级的提高,试件的黏结强度显著增大；当强度等级达到C55时,试件的破坏模式由钢筋屈服前破坏转变为钢筋屈服后破坏。基于试验数据,建立了钢筋煤矸石混凝土构件的黏结强度预测模型和三维细观有限元模型。在验证有限元模型准确性的基础上,利用该模型进一步揭示了煤矸石混凝土与带肋钢筋在拉拔力作用下的损伤演化和黏结破坏机理。

Abstract:

To investigate the bond-slip behavior between ribbed steel bar and coal gangue concrete, 36 cubic specimens were designed and prepared, in which coal gangue replacement ratio, concrete strength grade and rebar diameter were selected as variables, and the center pull-out tests were conducted. The results show that the bond strength of the specimen gradually decreases with the increase of coal gangue replacement ratio and the failure mode changes from pull-out failure to splitting failure. With the increase of rebar diameter, the bond strength of the specimen shows a decreasing trend, and the degree of decline of coal gangue concrete is more significant than that of ordinary concrete. As the concrete strength grade increases, the bond strength of the specimen increases significantly and the failure mode of the specimen changes from the pre-yield failure of steel bar to the post-yield failure of steel bar when the strength grade reaches C55. Based on the experimental data, a bond strength prediction model and a 3D meso-scale finite element model of reinforced coal gangue concrete members were established. The finite element model, the accuracy of which was verified, was utilized to further reveal the damage evolution and bond failure mechanism of coal gangue concrete and ribbed steel bar under pull-out force.