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通过对8根钢板-混凝土组合受弯加固简支梁(以下简称组合加固梁)的等幅疲劳加载试验,研究了组合加固梁在疲劳荷载作用下的寿命及应变变化规律。试验结果表明:组合加固梁的疲劳破坏是由钢板裂纹从栓钉焊趾处开始缓慢扩展直至贯通导致的,与普通钢筋混凝土梁相比,组合加固梁的疲劳破坏具有较好的延性;钢板应力幅对组合加固梁的疲劳性能影响较大,实际设计时应严格控制钢板的应力幅和应力上限,不宜采用高强钢材和较薄的钢板;加固层预应力可有效提高组合加固梁的疲劳性能;按TB 10002.2—2005《铁路桥梁钢结构设计规范》中规定的焊有栓钉的受拉钢板的S-N关系对钢板-混凝土组合加固梁的钢板进行疲劳设计偏于安全。另外,提出了考虑应力水平影响的组合加固梁疲劳寿命的计算方法。
The fatigue life and strain changes of the composite reinforced beam under fatigue load were studied through the equal amplitude fatigue loading test of eight steel-concrete composite flexural strengthened simply supported beams (hereinafter referred to as composite reinforced beams). The experimental results show that the fatigue failure of the composite reinforced beams is caused by the slow crack propagation extending from the crack tip of the studs to the penetration through the composite reinforcement beams. Compared with ordinary reinforced concrete beams, the fatigue failure of the composite reinforced beams has good ductility. The effect of the amplitude on the fatigue performance of the composite reinforced beams is great. In the actual design, the stress amplitude and the upper stress limit of the steel plate should be strictly controlled. High strength steel and thinner steel plates should not be used. The prestressed reinforcement layer can effectively improve the fatigue performance of the composite reinforced beam. According to TB 10002.2-2005 “Railway Bridge Steel Structure Design Code,” the provisions of the stud welded stud SN relationship between the steel plate - concrete composite reinforced beams of steel fatigue design is biased towards safety. In addition, the calculation method of the fatigue life of the composite reinforced beam considering the influence of stress level is proposed.