高强钢筋轻骨料混凝土梁短期裂缝试验研究

进行了10根配置400MPa和500MPa高强纵筋的陶粒轻骨料混凝土梁受弯性能试验，获得了10组裂缝间距和39组短期裂缝宽度数据，并收集了国内外27根高强钢筋轻骨料混凝土梁的裂缝试验数据。采用以上数据，分析了钢筋轻骨料混凝土梁的裂缝特征，并评估了JGJ 12—2006《轻骨料混凝土结构技术规程》中裂缝计算公式的适用性。结果表明，JGJ 12—2006的短期裂缝特征值计算方法仍适用于高强钢筋轻骨料混凝土梁，但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与试验值有一定偏差，二者之比的均值为0.992、1.276和1.037，因此建议对JGJ 12—2006中公式的部分参数进行修正。通过对试验数据的回归分析，得到了梁侧面受拉纵筋中心处裂缝宽度的修正计算式，以及梁侧面受拉钢筋中心处与受拉边缘裂缝宽度的换算关系式，建议公式计算得到的裂缝宽度和试验值吻合较好。

Experimental investigation on short-term cracking behavior of lightweight concrete beams reinforced with high-yield strength rebars

Tests were conducted to investigate the flexural behavior of ten ceramsite lightweight concrete beams reinforced with 400MPa and 500MPa high-yield strength rebars were tested. Ten crack spacing data and 39 short-term crack width data were obtained from these tests. Meanwhile, the other cracking test results of 27 lightweight concrete beams reinforced with high-yield strength rebar were collected at home and abroad. Based on the cracking test data, the characteristics of cracks in reinforced lightweight concrete beams were analysed. The formulae for the crack width of reinforced lightweight concrete beam specified in JGJ 12—2006 ‘Technical specification for lightweight aggregate concrete structures’ was evaluated using the test data. The analysis results show that the calculating method for short-term crack width in JGJ 12-2006 is adaptable to lightweight concrete beams reinforced with high-yield strength rebar, but the values calculated according to JGJ 12—2006 of average crack spacing, average crack width and maximum crack width in general are deviated from those test values with the average ratios of 0.992, 1.276 and 1.037. So it is necessary to revise some parameters of the formulae. Using regression analysis, the revised formulae for the crack width at the centre of tensile longitudinal rebar on the side of the beam were suggested. Conversion formulas for the average crack width at the position of tensile steel rebar and the tensile edge was proposed. The calculated values obtained by the proposed formulae are in good agreement with the test results.