武器间接命中条件下FRP约束混凝土抗多次打击能力
EXPERIMENTAL STUDY OF RESISTING MULTI-HITTING CAPACITY ON FRP CONFINED CONCRETE ON CONDITION OF INDIRECT DAMAGE BY WEAPONS
-
摘要: 在3种约束比下FRP约束混凝土圆柱体试件准静载和快速加载试验的基础上,进行多次打击试验及多次打击后的准静载试验 。结果表明:FRP约束混凝土是一种抗多次打击能力较好的抗压复合材料,经每次打击后的刚度虽逐渐衰减,但有收敛趋势,其残余刚度随约束比ξ及最大应力比η的增加而减小。经受多次打击后的FRP约束混凝土与未经受多次打击的试件相比,其准静载下的初始弹性模量降低,强度基本不变,极限应变提高,其中弱约束混凝土延性提高得尤其显著,强约束混凝土应力-应变曲线中线性强化段的斜率随刚度衰减程度的增加而增加,最终FRP强约束混凝土有变成线弹性材料的趋势,为进一步研究FRP约束混凝土在防护结构中的应用提供条件。Abstract: Based on the quasi-static and rapid loading test results of short cylindrical concrete specimens wrapped with fiber reinforced plastic (FRP) under three different constraint ratios(ξ), the multi-hitting test and quasi-static loading test after multi-hitting were conducted. The test results show that FRP confined concrete is a kind of material which can well resist multi-hitting. The stiffness of FRP confined concrete decreases along with increasing hitting times and also gradually converges. The final residual stiffness decreases along with ξ and η(ratio between maximum hitting stress and strength of FRP confined concrete) increase. For FRP confined concrete damaged by multi-hitting, compared with intact specimens, the elastic modulus decreases, while the strength is nearly unchanged and the ultimate strain increases. Ductility of FRP weak-confined concrete damaged by multi hitting obviously increases. The slope of linear strengthening of the stress-strain curve of FRP well-confined concrete damaged by multi-hitting increases along with the damage degree increasing and the final stress-strain curve of FRP well-confined concrete gradually approaches to linear elastic. This work provides the basis for further research on application of FRP confined concrete to defending structures.