钢筋钢纤维高强混凝土梁疲劳试验研究及刚度计算

通过1根钢筋高强混凝土梁和12根钢筋钢纤维高强混凝土梁的静载及等幅疲劳试验，分析静载和疲劳荷载作用下钢筋钢纤维高强混凝土梁挠度和刚度变化规律，以及疲劳应力比、钢纤维类型、钢纤维体积率、钢纤维掺入截面高度和混凝土强度等对钢筋钢纤维高强混凝土梁挠度的影响。结果表明：在钢筋高强混凝土梁中掺加钢纤维能有效限制梁刚度的退化，显著提高梁的抗弯刚度，减小梁的跨中挠度，使静载和疲劳荷载作用下梁的跨中挠度分别降低了19.0%~69.1%和15.0%~61.0%。在试验研究的基础上，通过理论分析修正了静载作用下钢纤维影响梁短期刚度的系数，提出了考虑疲劳次数和钢纤维含量特征值影响的钢筋高强混凝土梁疲劳刚度的计算方法，并将计算结果与试验结果进行了对比，两者符合较好。

Fatigue test and stiffness calculation of steel fiber reinforced high-strength concrete beams with reinforcements

Based on the tests of one high-strength concrete beam and twelve steel fiber reinforced high-strength concrete beams under static and fatigue load, the behavior of deflection and stiffness of steel fiber reinforced high-strength concrete beams with reinforcements under static and fatigue load was analyzed. The influences of fatigue stress characteristic, steel fiber types, steel fiber volume fraction, depth of steel fiber layer and concrete strength on the stiffness of steel fiber reinforced high-strength concrete beams with reinforcements were investigated. The results show that the addition of steel fiber into high strength concrete beams can restrain stiffness degradation and control the deformation effectively, the deflection of steel fiber reinforced high-strength concrete beams with reinforcements decreases by 19.0%～69.1% under static load and by 15.0%～61.0% under fatigue load respectively. Based on the test results and theoretical analysis, the calculating method and formulas of stiffness of steel fiber reinforced high-strength concrete beams with reinforcements are proposed, which consider the influences of fatigue stress characteristic and steel fiber volume fraction on stiffness. It is shown that the calculating result by the stiffness formulas in this paper agrees well with the experimental data.