高强钢筋钢纤维高强混凝土梁受弯裂缝宽度影响系数的概率分布与取值建议

Probability distribution and recommended value of impact coefficient on crack width in steel fiber reinforced high-strength concrete beams with high-strength reinforcements

为研究钢纤维对正常使用阶段下受弯梁最大裂缝宽度的影响,对17根高强钢筋钢纤维高强混凝土梁和1根高强钢筋高强混凝土梁进行受弯试验。结果表明,掺入钢纤维可有效减小高强钢筋高强混凝土受弯梁的最大裂缝宽度,钢纤维对高强钢筋钢纤维高强混凝土梁裂缝宽度影响系数大于JGJ/T 465—2019《钢纤维混凝土结构设计标准》中规定值。在此基础上,研究我国现行规范中反映钢纤维对钢筋混凝土梁受弯裂缝宽度影响的系数值用于计算高强钢筋钢纤维高强混凝土梁最大裂缝宽度的适用性。通过收集国内外文献中的受弯梁试验数据,分析裂缝宽度影响系数的概率分布,得到不同保证率下裂缝宽度影响系数值,提出裂缝宽度影响系数的建议取值0.45。

In order to investigated the influence of steel fiber on the maximum crack width of RC beam under normal serviceability states,17 steel fiber reinforced high-strength concrete(SFRC) beams and one reinforced high-strength concrete(RC) beam with high-strength steel bars were investigated by means of flexural experiments.Test results indicate that the maximum crack width of RC beam with high-strength steel bars under bending obviously decreases with the addition of steel fibers,and steel fiber impact coefficient value on the crack width of SFRC beam with high-strength steel bars is greater than that specified in JGJ/T 465—2019 “Standard for design of steel fiber concrete structures”.The applicability of the impact coefficient of steel fiber in current code of China for the calculation of maximum crack width of SFRC beam with high-strength steel bars,of which the impact coefficient value is used to reflect the influence of steel fiber on the maximum crack width of SFRC beam under bending,is also discussed.The probability distribution of steel fiber impact coefficient on the crack width was analyzed through the experimental data of flexural beams collected from relevant literatures,and the impact coefficient for the different types of steel fibers with various guarantee rates were obtained.Finally,the suggested value of steel fiber impact coefficient on the crack width was proposed to be 0.45.