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作 者:白玉磊[1] 孙鹏轩 贾俊峰[1] BAI Yulei;SUN Pengxuan;JIA Junfeng(Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology,Beijing 100124,China)
机构地区:[1]北京工业大学城市与工程安全减灾教育部重点实验室,北京100124
出 处:《复合材料学报》2022年第10期4732-4745,共14页Acta Materiae Compositae Sinica
基 金:国家自然科学基金(51778019,51978017);北京市自然科学基金(8212003);北京市教委青年拔尖人才培养计划项目(CIT&TCD201904018)。
摘 要:大应变纤维增强聚合物复合材料(LRS FRP)具有大断裂应变(大于5%)的特性,可能带来较高的结构延性,为钢筋混凝土(RC)柱的抗震加固提供了一种新的选择。外包FRP通过混凝土保护层为纵筋提供侧向支撑,防止或减缓纵筋的屈曲。但当箍筋间距较大时纵筋仍可能发生屈曲,尤其是在FRP不均匀约束的矩形柱中,纵筋的提前屈曲降低了柱子的承载能力。为研究不均匀约束情况下,FRP加固柱中钢筋的屈曲行为,本文共设计了28个聚对苯二甲酸乙二醇酯(Polyethylene terephthalate,PET) FRP约束矩形试件,包括16个RC柱和12个素混凝土(PC)柱,对其进行单调轴压试验,研究FRP层数、箍筋间距和截面形状比对约束柱承载力和延性的影响;从试验结果中得到纵筋的平均应力-应变曲线,对FRP约束RC柱中纵筋的应力-应变关系进行定量分析。结果表明,PET FRP约束RC柱可提高其强度和延性,在一定范围内,当约束刚度越大、截面形状比越接近1时,约束效果越好;外包FRP的侧向支撑作用可将纵筋的屈曲推迟到较高的变形水平。Large-rupture-strain fiber reinforced polymers(LRS FRPs) have the large tensile rupture strain value of more than 5%. This characteristic might enhance the load-bearing capacity and ductility and provide a new choice for seismic strengthening of reinforced concrete(RC) columns. The FRPs provide lateral support for the longitudinal bars through the cover concrete, which might prevent or delay the buckling of longitudinal steel bars. However,the buckling of the longitudinal reinforcement might still be observed when the stirrup spacing is relatively large.Especially, for the FRP-confined rectangular columns, the ununiform confinement provided by the external FRP for the specimen might result in the buckling of longitudinal bars and reduce the load-bearing capacity of the specimen. In order to study the buckling behavior of longitudinal bars in rectangular RC columns confined by FRP, a total of 28 polyethylene terephthalate(PET) FRP-confined rectangular columns, comprising 16 RC columns and 12plain concrete(PC) columns, were prepared and tested under monotonic axial compression. The effects of the thickness of external FRP jackets, stirrup spacing and section aspect ratio on the load-bearing capacity of FRP-confined RC columns were studied. To carry out a quantitative study on the buckling behavior of longitudinal steel bars in FRP-confined RC columns, the average axial stress-strain curve of a single longitudinal bar was obtained from the test results. The experimental results show that the application of PET FRP jackets can effectively improve the loadbearing capacity and ductility of RC columns. A large confinement stiffness and a low section aspect ratio close to 1lead to a high confinement level for RC columns. And the lateral support of FRP can delay the buckling of the steel bars to a higher deformation level.
关 键 词:聚对苯二甲酸乙二醇酯纤维增强聚合物 纵筋屈曲 单调轴压 纤维增强聚合物约束柱 侧向支撑
分 类 号:TB332[一般工业技术—材料科学与工程]
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