织物增强超高延性混凝土单轴动态拉伸性能研究

Investigation on uniaxial dynamic tensile behavior of textile-reinforced ultra-high ductility concrete

  • 摘要: 织物增强超高延性混凝土(textile-reinforced ultra-high ductility concrete,TR-UHDC)是一种具有高抗拉强度、拉伸应变硬化和多缝开裂等特点的新型水泥基复合材料。为研究TR-UHDC在动荷载下的拉伸力学性能,设计了38组单轴拉伸试件,研究动荷载应变速率、聚乙烯(polyethylene,PE)短纤维体积掺量、织物配网率、超高延性混凝土基体类型等因素对TR-UHDC开裂模式、拉伸应力-应变曲线的影响,并根据特征参数评估TR-UHDC的应变率敏感性。结果表明:1)随短纤维掺量提高,试件呈现出多缝开裂模式和织物断裂失效特点,PE短纤维在动荷载作用下仍可有效提高织物-基体之间的黏结性能;2)TR-UHDC抗拉强度的动力增长系数最大可达1.637,参数分析表明TR-UHDC具有显著的应变速率效应;3)基于应变速率建立抗拉强度分析模型,可有效预测TR-UHDC在动态和静态荷载下的抗拉强度,为工程设计中的动态抗拉强度提供依据,可降低TR-UHDC在结构抗震加固应用中的潜在设计风险。

     

    Abstract: Textile-reinforced ultra-high ductility concrete (TR-UHDC) is a new type of cement-based composite material with high tensile strength, tensile strain-hardening and multi-cracking properties. To study the dynamic tensile mechanical properties of TR-UHDC under dynamic load, 38 sets of uniaxial tensile specimens were designed to investigate the effects of dynamic strain rate, polyethylene (PE) short fiber volume content, textile reinforcement ratio, matrix types of ultra-high ductility concrete on the cracking mode and tensile stress-strain curves of TR-UHDC. The strain rate sensitivity of TR-UHDC was evaluated based on the characteristic parameters. The results show that: 1) With the increase of short fiber content, the specimens exhibit multi-cracking characteristics and textile fracture. The short PE fiber can still effectively improve the bonding performance between the textile and the matrix under dynamic load; 2) The dynamic impact coefficient of the tensile strength of TR-UHDC can reach a maximum of 1.637. The parameter analysis indicates that TR-UHDC has a significant strain rate effect; 3) The analysis model established based on the strain rate can effectively predict the tensile strength of TR-UHDC under dynamic and static loads. It provides a foundation for the dynamic tensile strength in engineering design and reduces the potential design risks of TR-UHDC in the field of structural seismic reinforcement.

     

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