冻融循环作用下保温混凝土黏结滑移本构模型研究

Bond-slip constitutive model of thermal insulation concrete after freeze-thaw cycles

冻融循环作用下,钢筋与混凝土之间的黏结锚固性能遭到破坏,而钢筋与混凝土之间的黏结滑移本构关系模型能够综合反映两者间的黏结锚固性能。通过中心拉拔试验,研究了冻融循环作用下钢筋与玻化微珠保温混凝土(TIC)黏结锚固性能的退化规律,测定了试件的黏结滑移曲线,并与普通混凝土(NC)对比分析。研究结果表明:冻融循环次数增大,钢筋与TIC试件黏结锚固作用减弱,极限黏结强度减小,峰值滑移增大,与NC试件变化规律一致;相同冻融循环次数后,TIC试件的极限黏结强度大于NC试件,且其峰值滑移小于NC试件;冻融循环200次后,TIC试件破坏形式为拔出破坏,而NC试件为劈裂破坏。进一步基于试验研究,提出了冻融循环作用前后钢筋与玻化微珠保温混凝土黏结滑移本构关系模型,该模型与试验结果吻合较好,对于玻化微珠保温混凝土材料在工程实践中的应用和相应规范的完善具有参考价值。

Under the action of freezing and thawing,the bond anchoring property between steel and concrete is destroyed,and the bond-slip constitutive model between steel and concrete can comprehensively reflect the bond anchoring property.The degradation law of the bond anchoring performance of steel bars and thermal insulation concrete(TIC)under freeze-thaw cycles was studied through the central pull-out test.The bond slip curves of the test specimens were measured and compared with normal concrete(NC).The results indicate that with the increase of the number of freeze-thaw cycles,the the bond anchoring performance of steel bars and TIC decrease,the ultimate bond strength decreased,and the peak slip increased,which was consistent with the variation of NC specimens;after the same number freeze-thaw cycles,the ultimate bond strength of the TIC specimens is greater than that of the NC specimens,and the peak slip is smaller than that of the NC specimens.After 200 freeze-thaw cycles,the TIC specimens are pulled out and destroyed,and the failure mode of NC specimens is splitting failure.Based on the experimental research,the bond-slip constitutive model of steel and thermal insulation concrete after freezing-thawing cycle is proposed.Good agreement is achieved between the test curves and the predicted curves.It has reference value for the application of thermal insulation concrete in engineering practice and the improvement of corresponding standards.