玄武岩纤维混凝土板冲切试验与承载力分析

Punching Shear Test and Bearing Capacity Analysis of Basalt Fiber Concrete Slab

为探究玄武岩纤维对混凝土板抗冲切性能的增强效果,基于我国现行规范对此类构件冲切承载力计算方法提出修正建议。以纤维体积掺量(0%、0.1%、0.2%、0.3%)与纤维长度(12 mm、18 mm)为变量,对7个混凝土板试件进行冲切试验,研究各参数对试件极限承载力的影响,建立经试验验证的有限元模型并进行扩参数分析。结果表明:玄武岩纤维混凝土板的极限承载力随体积掺量的增加呈先增大后减小的趋势,掺入长度为12 mm、18 mm的玄武岩纤维的试件较对比试件冲切承载力提升显著,最大提高幅度分别为40.9%和37.3%;纤维长度为12 mm,体积掺量为0.4%时,对混凝土板的抗冲切性能改善效果最佳。我国《混凝土结构设计规范》(GB 50010—2010)的冲切承载力计算值较试验结果偏于保守,考虑玄武岩纤维阻裂作用对临界截面周长的影响,对规范中的冲切承载力计算公式进行修正。

In order to explore the enhancement effect of basalt fiber on the punching shear resistance of concrete slab,and propose amendments to the calculation method for the punching shear bearing capacity of such components,based on the current norms in China.The volume content of fiber(0%,0.1%,0.2%,0.3%)and the fiber length(12 mm,18 mm)were taken as variables.The effect of each variables on the ultimate bearing capacity of seven concrete slab specimens was studied by punching shear test.Moreover,a finite element analysis model verified by the test was established for expansion parameter analysis.The results show that with the increase of volume content,the ultimate bearing capacity of basalt fiber concrete slab increases first and then decreases.Furthermore,the specimens of basalt fibers with a length of 12 mm and 18 mm are significantly higher than the specimens without fibers,with the maximum increase of 40.9%and 37.3%,respectively.The punching shear resistance of concrete slab is best improved when the fiber length is 12 mm and the volume content is 0.4%.The calculation value of the punching shear bearing capacity of the code for design of concrete structures(GB 50010—2010)in China is more conservative than the test results.Considering the effect of preventing cracking of basalt fibers on the circumference of critical section,the calculation formula of the punching shear bearing capacity of the code is modified.