配置高强钢筋的后张有黏结预应力梁短期裂缝试验研究

进行了29根配置500MPa级钢筋的后张有黏结预应力混凝土梁的受弯性能试验，获得了29组裂缝间距和96组短期裂缝宽度数据；收集了国内外29根后张有黏结预应力梁的裂缝试验数据。采用以上试验数据，分析了后张有黏结预应力混凝土梁的短期裂缝特征，并评估了GB 50010—2010《混凝土结构设计规范》中裂缝计算公式的适用性。研究结果表明：规范GB 50010—2010的短期裂缝计算方法仍适用于配置高强钢筋的后张有黏结预应力梁，按其公式计算的平均裂缝间距、平均裂缝宽度和最大裂缝宽度较试验值普遍偏大，二者之比的均值分别为1.086、1.313和1.263。因此，建议对GB 50010—2010规范公式部分参数进行修正，并建议将计算裂缝宽度明确为梁侧面最外排受拉钢筋中心处、钢筋应力取为最外排受拉钢筋的应力。通过参数回归分析，得到裂缝宽度的修正计算公式，并提出梁侧面最外排受拉钢筋中心处与受拉边缘、预应力筋中心处的裂缝宽度的换算关系式，建议公式的计算值和试验值符合较好。

Experimental investigation on short-term cracking behavior of bonded post-tensioned concrete beams with high-yield strength rebars

Twenty-nine post-tensioned concrete beams reinforced with 500MPa yield strength steel bars were tested.Twenty-nine crack spacing data and ninety-six short-term crack width data were obtained from these tests. Meanwhile,the other cracking test results of twenty-nine post-tensioned concrete beams were collected. The formulae for the crack spacing and crack width of bonded post-tensioned concrete beam specified in GB 50010—2010 ‘Code for design of concrete structures’ was evaluated using the test data. The analysis results show that the method in GB 50010—2010 is adaptable to bonded post-tensioned concrete beams with high-yield strength rebars, but the values calculated according to GB 50010—2010 of average crack spacing, crack widths and maximum crack width are in general more than those test values with the average ratios of 1.086, 1.313 and 1.263. So it is necessary to revise some parameters of the formulae.The position of calculated crack width is suggested at the outermost longitudinal tension rebar and the stress of tension rebar is suggested to be the stress of the outermost longitudinal tension rebar.Using regression analysis, the revised formulae of the crack width were suggested. Conversion formulas for the average crack width at the position of tensile steel rebar and the tensile edge or prestressing tendon were proposed. The proposed calculation formulas agree with the test results.