通过8根HRB500级高强钢筋混凝土梁以及2根普通钢筋混凝土梁的受弯试验,对比分析试验梁的裂缝分布、平均裂缝宽度及短期最大裂缝宽度的变化特性.结合已有试验结果,对56根500级钢筋混凝土梁的受弯开裂特性进行综合研究,结果表明:试验梁的平均裂缝间距与规范GB 50010-2002公式的计算值符合得较好,而短期最大裂缝宽度计算值则大于实测值,尤其是当钢筋应力超过300N/mm2的情况.鉴于此,在参照国外相关规范的基础上,对该类梁的裂缝宽度计算提出了两种修正建议:①适当调整短期最大裂缝宽度的保证率,取90%的保证率可使计算平均值降低10%左右;②调整裂缝截面处钢筋应力的计算值,具体有两种途径,一是取准永久荷载组合进行计算,二是将钢筋应力超过某一值后取为定值,若将该应力定值取为300N/mm2,裂缝宽度比值的均值为1.063,变异系数为0.176,计算效果非常理想.%Based on the flexural tests of eight reinforced concrete ( RC) beams with HRB500 steel bars and two beams with ordinary reinforcements, the crack distribution, mean crack width as well as short-term maximum crack width were analyzed and compared. With the collected experimental data of fifty-six beams with HRB500 steel bars, the cracking property of flexural beams was investigated. The results indicate that the measured values of mean crack spacing are equivalent to the calculation results from formulas in code GB 50010-2002, whereas the calculated maximum crack widths are larger than the measured data, especially when the steel stress exceeded 300N/mm2. Therefore, two advices for crack width calculation are proposed on the basis of foreign codes: ①the guarantee rate for short-term maximum crack width should be modified properly and the mean value of calculation would reduce by about 10% with a guarantee rate of 90%; ②the calculation value of reinforcement stress at cracking section should be modified through the following two approaches. One is to adopt the mode of quasi-permanent load combination, and the other is to set a maximum stress of 300N/mm2, with which the calculations are adequate with a mean ratio value of 1.063 and a COV of 0.176.
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