摘要
为探究冲击荷载作用下GFRP管对混凝土结构的约束保护作用,采用非金属超声波分析仪测量不同冲击次数下GFRP约束混凝土试件纵波波速,利用直径为74 mm分离式霍普金森压杆装置(SHPB)对试件开展动态单轴劈裂拉伸试验,分析试件纵波波速、损伤因子、应力应变曲线、峰值应力与GFRP管壁厚度及冲击次数间的关系。结果表明:冲击次数的增加使得试件纵波波速降低,损伤因子增大,在第4次冲击荷载作用后管壁厚度1、1.5、2 mm试件损伤因子分别为29.56%、22.33%、17.77%,管壁厚度的增加,增加了对混凝土的径向约束,改善了混凝土内部的应力状态,降低了其在冲击荷载作用下的损伤度。素混凝土试件的动态拉伸应力应变曲线呈单峰曲线,GFRP约束混凝土试件的动态拉伸应力应变曲线呈双峰曲线,管壁与混凝土接触面处使得应力波产生透反射从而改变波的传播路径。相较于管壁厚度为0.5 mm试件,管壁厚度为1、1.5、2 mm在第1次冲击荷载作用下试件应力增幅为12.03%、24.97%、51.11%,2.0 mm管壁厚度时相较于第1次冲击荷载作用,第2、3、4次冲击作用下能量吸收率降幅为6.72%、12.75%、15.92%,试件峰值应力及破碎耗能密度随管壁厚度增加而增大,随冲击次数的增加而降低。
In order to explore the restraint and protection effect of GFRP tube on concrete structure under impact load,non-metallic ultrasonic analyzer was used to measure the P-wave velocity of GFRP restrained concrete specimen under different impact times.Dynamic uniaxial splitting tensile test was carried out on the specimen with a split Hopkinson pressure bar(SHPB)with a diameter of 74 mm.The relationship between longitudinal wave velocity,damage factor,stress-strain curve,peak stress and GFRP tube wall thickness and impact times was analyzed.The results show that with the increase of impact times,the longitudinal wave velocity decreases and the damage factor increases.After the fourth impact load,the damage factors of specimens with wall thickness of 1 mm,1.5 mm and 2 mm are 29.56%,22.33%and 17.77%,respectively.The increase of pipe wall thickness increases the radial constraint on concrete,improves the stress state inside concrete,and reduces the damage degree under impact load.The dynamic tensile stress-strain curve of the plain concrete specimen shows a single peak curve,and the dynamic tensile stress-strain curve of the GFRP constrained concrete specimen shows a double peak curve.The contact surface between the tube wall and the concrete causes the stress wave to produce a permeable reflection,thus changing the propagation path of the wave.Compared with specimens with 0.5 mm wall thickness,the stress increases of specimens with 1 mm,1.5 mm and 2 mm under the first impact load are 12.03%,24.97%and 51.11%.When the tube wall thickness is 2.0 mm,compared with the first impact load,the energy absorption rate under the second,third and fourth impacts decreases by 6.72%,12.75%and 15.92%.The peak stress and energy dissipation density of the specimen increase with the increase of the wall thickness,but decrease with the increase of the number of impact.
作者
马晓霞
孙燕飞
施春燕
赵磊
MA Xiaoxia;SUN Yanfei;SHI Chunyan;ZHAO Lei(Yinchuan University of Energy,Yinchuan 750100,China;Yantai City Planning Design Research Institute Co.,Ltd.,Yantai 264003,China;School of Architecture and Engineering,Zhejiang University,Hangzhou 310058,China)
出处
《混凝土》
CAS
北大核心
2023年第8期32-37,共6页
Concrete
基金
宁夏回族自治区第二批全区高校黄大年式教师团队银川能源学院土木工程教师团队(宁教师[2022]130号)
银川能源学院科学研究项目(2023-KY-Y-15)
国家自然科学基金(52078459)。
关键词
多次冲击荷载
GFRP
纵波波速
损伤因子
峰值应力
耗能密度
multiple impact loads
GFRP
longitudinal wave velocity
damage factor
peak stress
energy dissipation density
