疲劳荷载下钢筋钢纤维高强混凝土梁受压边缘累积残余应变计算方法

Calculation Method on Cumulative Residual Compressive Strain at Compressive Edge of Steel Fiber Reinforced High-strength Concrete Beams Under Fatigue Load

为了深入研究钢纤维高强混凝土梁的疲劳损伤演化过程,促进钢纤维混凝土在公路和桥梁工程中的应用,通过14根钢筋钢纤维高强混凝土梁的疲劳试验,分析了疲劳等效应力比、钢纤维体积率、钢纤维类型、钢纤维掺入截面高度和钢筋级别等因素对钢筋钢纤维高强混凝土梁受压边缘混凝土累积残余应变的影响。探讨了疲劳荷载作用下钢筋钢纤维高强混凝土梁受压边缘混凝土累积残余应变的计算方法,提出了考虑钢纤维含量特征参数、钢纤维掺入梁截面高度和混凝土强度影响的钢筋钢纤维高强混凝土梁受压边缘混凝土累积残余应变的计算公式。以梁受压边缘混凝土累积残余应变为依据,分析了疲劳累积损伤的发展过程。研究结果表明:钢筋钢纤维高强混凝土梁累积残余应变随着最大应力水平及疲劳循环次数的增加而增大,其发展具有明显的阶段性;钢纤维有效降低了累积残余应变的发展速率和梁的疲劳损伤程度。

To investigate fatigue damage evolution of steel fiber reinforced high-strength concrete beams and promote the application of steel fiber reinforced concrete in road and bridge engineering,the influences of factors,such as the fatigue equivalent stress ratio,steel fiber volume fraction,steel fiber type,the depth of the steel fiber adding into the beams and reinforcement grade,on the cumulative residual compressive strain of concrete at the compressive edge of steel fiber reinforced high-strength concrete beams were analyzed based on the fatigue tests of 14 steel fiber reinforced high-strength concrete beams.The method to calculate the cumulative residual compressive strain of concrete at beam compression edge under fatigue load was discussed,and its formulas which consider the impacts of steel fiber content characteristic parameters,depth of steel fiber adding into beams and strength of concrete were proposed.The development of fatigue cumulative damage was analyzed based on the cumulative residualcompressive strain of concrete at beam compression edge.The results show that the cumulative residual compressive strain of concrete at beam compression edge increases with the increase of the maximum stress level and fatigue cycles,and its development shows the significant feature of stage.The development rate of cumulative residual compressive strain and fatigue cumulative damage decrease with the addition of steel fiber effectively.