高强钢筋高强混凝土梁静力和疲劳性能试验研究

通过9根配有新Ⅲ级钢的高强混凝土梁和4根配有Ⅱ级钢的混凝土梁的静载和等幅疲劳荷载试验,分析研究了高 强混凝土梁的变形性能和疲劳特性。试验结果表明,在高强混凝土梁中应用高强钢筋,可以使两者的性能得以充分发挥, 不仅承载力大幅度提高,而且能较好的满足正常使用极限状态的要求。高强混凝土受弯构件在疲劳荷载作用下刚度降低, 裂缝宽度增大,其变化规律和受压区混凝土应变的增加规律基本一致。疲劳荷载作用N次后构件的裂缝宽度,可根据初 始裂缝宽度和受压区混凝土应变增长系数来计算。根据试验分析,得到了高强混凝土梁在疲劳荷载作用下的截面应力、裂 缝宽度及高强钢筋S-N曲线试验回归公式,可为高强混凝土梁设计提供一定的参考。

Experimental research of high-strength concrete beams reinforced by high-strength bars under static loading and fatigue loading

Nine high-strength concrete (HSC) beams reinforced by high-strength bars and four ordinary reinforced concrete beams were tested under static loading and fatigue loading with constant amplitudes. The static and fatigue behavior of flexural member were studied. The results indicated that HSC beam, applying higher tensile steel as reinforcement, can not only increase greatly the ultimate limit state of collapse, but also the limit state of serviceability. The stiffness of such beam will decrease, while the crack width will increase under fatigue load, and the variation regularity follows that of the increment of concrete strain on the edge of compressive zone. The relevent crack width can thus be calculated by preliminary crack width and increasing coefficient of concrete compressive strain after fatigue loading operation N times. It has been found that the analytical model is able to predict the crack width satisfactorily, when compared with the measured crack width for each of the beams, from the cracking stage to the stage just prior to failure. Through analyses and derivations, the calculation formulas for crack width and the calculation methods of stress for HSC beams under fatigue loading, as well as high-strength steel bar fatigue S-N curve are presented. The results can be used as reference for HSC beam design.