钢板-混凝土组合受弯加固梁疲劳性能试验研究

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。图19表6参12

Experimental research on fatigue behavior of RC beams strengthened by steel plate-concrete composite technique

Based on fatigue experiments on eight RC beams strengthened by steel plate-concrete composite (SPCC) technique, fatigue life and variation trend of strain under constant amplitude fatigue loading were studied. The experimental results show that the fatigue failure mode of steel plate-concrete composite beam is fatigue failure of the steel plates. The initial fatigue crack in steel plates appears near the welded toe of stud and then expansion though. But different from general RC beams, the fatigue failure mode of specimens is ductile. Amplitude of stress in steel plate has most important influence on fatigue behavior of RC beams strengthened by SPCC technique. Level and amplitude of stress in steel plate should be controlled strictly in practical design and high strength steel and thin steel plate are not suitable for RC beams strengthened by SPCC technique. The pre-stress in steel plate can improve fatigue life of RC beams strengthened by SPCC technique. The S-N relation for tension steel plate welded with studs provided in ‘Code for railway steel bridges design’ is safe enough for the design of steel plates in RC beams strengthened by SPCC technique. The calculational method for fatigue life is proposed considering effects of stress level and stress amplitude.12Refs.In Chinese.