首页|常温养护超高性能混凝土弯拉性能及轴拉本构模型

常温养护超高性能混凝土弯拉性能及轴拉本构模型

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根据水化反应方程和紧密堆积理论确定了常温养护下超高性能混凝土(UHPC)的基础配合比,基于此考虑水胶比和钢纤维掺量设计了 8 组 UHPC 抗弯试件.通过四点弯曲试验,分析了试件的受弯破坏形态、荷载-挠度曲线、弯拉特征参数和弯曲韧性等;基于试验结果采用倒推方法得到了UHPC轴拉应力-应变曲线,采用回归分析提出了考虑纤维特征的轴拉本构模型,并经过材料和构件两个层次的验证.结果表明:掺加钢纤维可抑制主裂缝的发展,从而明显改善 UHPC 的抗弯韧性,钢纤维掺量为 2.0%的UHPC弯曲韧性指数达到 116.9 J;随着水胶比增大,试件抗折强度和峰值挠度均呈下降趋势;增大钢纤维掺量明显提升了试件弯曲性能,掺入 2.0%钢纤维的 UHPC与未掺纤维相比,其初裂挠度和抗折强度分别提升 157.14%和 148.63%;当纤维含量为 1.5%～2.0%时,试件具有良好的弯拉性能;水胶比对曲线平台段趋势影响不大,纤维掺量大于 1.0%时曲线具有较明显的应变硬化特征,可保证UHPC良好的抗拉性能,其应变硬化特征随着纤维掺量增大而变得更明显;所提模型对UHPC受拉应力-应变关系具有较好的预测性.
Bending-tension performance and axial tension constitutive model of ultra-high performance concrete under normal temperature curing
The basic mix proportion of ultra-high performance concrete(UHPC)under normal temperature curing was determined based on the hydration reaction equation and the compact packing theory.Eight groups of UHPC flexural specimens were designed considering the water-binder ratio and steel fiber content based on the proportion.The bending failure mode,load-deflection curve,bending-tension characteristic parameters,and bending toughness of the specimens were analyzed by four-point bending tests.Based on the test results,the UHPC axial tension stress-strain curve was obtained by using the backward analysis method.The axial tension constitutive model considering fiber characteristics was proposed using regression analysis and validated at both material and component levels.The results show that the addition of steel fibers can suppress the development of main cracks,thereby significantly improve the bending toughness of UHPC.The bending toughness index of UHPC with 2.0%steel fiber content reaches 116.9 J.As the water cement ratio increases,the flexural strength and peak deflection of the specimen both show a decreasing trend.Increasing the steel fiber content can significantly improve the bending performance of the specimens.Compared with the specimens untreated by fibers,the initial crack deflection and flexural strength of UHPC with 2.0%steel fibers increased by 157.14%and 148.63%respectively.When the fiber content is between 1.5%and 2.0%,the specimen exhibits good flexural and tensile properties.The water cement ratio has little effect on the trend of the platform section of the curve.When the fiber content is greater than 1.0%,the curve has obvious strain hardening characteristics,which can ensure the good tensile performance of UHPC.The strain hardening characteristics become more obvious with the increase of fiber content.The proposed model has good predictive ability for the tensile stress-strain relationship of UHPC.

ultra-high performance concretenormal temperature curingbending-tension per-formancebackward analysis methodaxial tension constitutive model

梁林、王秋维、史庆轩、韩文超、于婧

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西安建筑科技大学 土木工程学院,陕西 西安 710055

西安建筑科技大学 绿色建筑全国重点实验室,陕西 西安 710055

西安建筑科技大学 结构工程与抗震教育部重点实验室,陕西 西安 710055

超高性能混凝土 常温养护 弯拉性能 倒推分析方法 轴拉本构模型

国家自然科学基金国家自然科学基金陕西省教育厅协同创新中心项目陕西省自然科学基础研究计划

521785055187854323JY0432020JM-487

2024

10.19815/j.jace.2022.05034

建筑科学与工程学报
长安大学 中国土木工程学会

建筑科学与工程学报

CSTPCD北大核心
影响因子：0.692
ISSN：1673-2049
年,卷(期)：2024.41(3)
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