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工程科学与技术:2022,54(4):112-120
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高温后灌浆料静动态单轴受压力学性能
(1.同济大学 土木工程学院,上海 200092;2.井冈山大学 建筑工程学院,江西 吉安 343009)
Static and Dynamic Mechanical Behaviors of Heat-damaged Cementitious Grout Under Uniaxial Compression Loadings
(1.College of Civil Eng., Tongji Univ., Shanghai 200092, China;2.College of Building Eng., Jinggangshan Univ., Ji’an 343009, China)
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投稿时间:2021-02-15    修订日期:2021-04-07
中文摘要: 灌浆料是套筒灌浆连接的关键组成部分,其受力本构关系的建立,能为套筒灌浆连接火安全设计方法的形成提供技术支持。通过36个小棱柱体试件的单轴受压试验,先开展高温试验(最高温度≤600 ℃),冷却至室温后,再设置静、动态加载应变率,研究高温后灌浆料的单轴受压力学性能。结果表明:采取105 ℃预烘干120 min,结合升温速率5 ℃/min的复合措施,抑制抗压强度为85.7 MPa灌浆料的爆裂;灌浆料试件的失效模式为竖向通缝式开裂,且随着应变率的增大,试件表面发生明显的剥落现象;动态加载应变率为0.067 s–1下,高温后普遍高于静态下的试件峰值应力值,最高可达29.6%;动态加载应变率为0.001 s–1下,高温后试件的弹性模量低于常温值,峰值应变高于常温值,其中,弹性模量下降幅度最大可达57.0%,峰值应变增大幅度最大可达13.2%;高温后灌浆料应力–应变归一化曲线包括上升、下降两部分,二者均呈现非线性发展特征;通过试验数据的拟合分析,建立高温后灌浆料单轴受压归一化静动态本构模型,并将其应用于高温后套筒灌浆连接高应力反复拉压的有限元模拟分析。模拟对象的荷载–位移曲线、峰值荷载等特征与实测结果吻合度较高,且率先实现模拟对象的套筒外钢筋断裂,得到400 ℃为高温作用后套筒灌浆连接失效模式转变的临界温度。
Abstract:Cementitious grout is the crucial part of the grouted sleeve connection, and its constitutive relationship under loading is the technical support to form the fire safety design method for grouted sleeve connections. The tests with 36 small prism specimens were conducted to study the uniaxial compressive behaviors of heat-damaged cementitious grout under static or dynamic loading strain rates after the specimens were exposed to elevated temperatures up to 600 ℃. It was found that explosive spalling was inhibited by the combined measures of pre-drying temperature with 105 ℃ in 120 min and the heating rate with 5 ℃/min. There were other findings after the specimens being loaded as follows: all specimens were failed to several vertical fractures with full-length along the height, and there were obvious spalling occurring to the specimens under the dynamic strain rate loadings; the compressive strength of heat-damaged specimens under dynamic loading strain rate with 0.067 s–1 were higher than that under static loading, which was up to 29.6%; the elastic modulus and the peak strains of heat-damaged specimens under the dynamic loading strain rate with 0.001 s–1 decreased and increased along with the increasing of elevated temperatures, respectively; compared to these of specimens at ambient temperature, the declining range of elastic modulus was up to 57.0% and ascending range of the peak strain was beyond 13.2%; the normalized curves between stress and strain of heat-damaged specimens contained ascending and declining segments, both of which were nonlinear curves; based on the experimental data, a combined static and dynamic uniaxial compression model of heat-damaged cementitious grout was built and used for the finite element simulation of heat-damaged grouted sleeve connections under high-stress cyclic loading. It was found that the peak loads and load-displacement curves from the simulation were consistent with the test results. In addition, the failure pattern of heat-damaged grouted sleeve connections under high-stress cyclic loading with rebar fracture outside the sleeve was firstly demonstrated in the simulation and 400 ℃ was the critical temperature that failure pattern of rebar fracture outside the sleeve converted into the bond-slip failure between cementitious grout and rebar after the connections were exposed to elevated temperatures.
文章编号:202100143     中图分类号:TU375;TU371.1    文献标志码:
基金项目:国家自然科学基金面上项目(52078358);江西省教育厅科技计划项目(GJJ201010)
作者简介:第一作者:刘良林(1983-),男,博士生.研究方向:预制混凝土结构抗火.E-mail:tlliu@tongji.edu.cn;通信作者:肖建庄,E-mail:jzx@tongji.edu.cn
引用文本:
刘良林,肖建庄,李建新,张凯建,丁陶.高温后灌浆料静动态单轴受压力学性能[J].工程科学与技术,2022,54(4):112-120.
LIU Lianglin,XIAO Jianzhuang,LI Jianxin,ZHANG Kaijian,DING Tao.Static and Dynamic Mechanical Behaviors of Heat-damaged Cementitious Grout Under Uniaxial Compression Loadings[J].Advanced Engineering Sciences,2022,54(4):112-120.