体内预应力组合梁裂缝宽度静力及疲劳试验研究

针对混凝土翼板内配置后张有粘结预应力筋的负弯矩区组合梁,进行7个简支试件的静力及疲劳试验,试验考虑了不同预应力度、不同栓钉间距,且混凝土翼板中配置有体积配纤率分别为0%、0.8%和1.5%的钢纤维。试验表明,极限状态时各试件的裂缝分布相似,裂缝平均间距在80~110 mm范围内。分析认为,影响裂缝宽度的因素包括预应力度、配纤率、力比、连接度、配筋率及栓钉间距等,提出考虑上述因素的最大裂缝宽度经验计算公式。疲劳试验中,运用测试动力参数的方法,分析混凝土裂缝和疲劳损伤随荷载循环的变化,结果表明,预应力钢纤维混凝土-钢组合梁带裂缝工作时具有良好的疲劳稳定性,180万次的循环加载损伤度增大约20%。

Static and Fatigue Experimental Study on Crack Width of Interior Prestressed Composite Beams

Seven simple supported steel-concrete composite beams, in which the flanges proportioned with prestressing tendons, are tested for static and fatigue analysis. The test specimens were designed with different pre-stressing degrees, different stud spacings, and the steel fibre ratios inside concrete flanges are 0%, 0.8% and 1.5% respectively. Static result shows that the crack distributions at ultimate status are similar and the average crack width is about 80 - 110 mm for different situations.From the result analysis, it was found that the prestressing-degree, fiber-ratio, force-ratio, connection-degree, reinforeement-ratio and shear stud spacing, etc. would affect the width of the crack. Considering such factors, an equation is proposed for calculation of the maximum crack width. The relationship between the concrete crack width and the fatigue damage with the loading cycles are tested and recorded using dynamic coefficient method. Test result shows that SFRC prestressed composite beam with crack development inside the concrete is working steady under fatigue load and the damage degree increased only 20% after 1.8 million loading cycles.