不同冷却方式下锈蚀钢筋混凝土梁短期刚度和裂缝宽度计算方法研究

RESEARCH ON THE CALCULATION METHOD FOR SHORT-TERM BENDING CRACK WIDTH AND STIFFNESS OF CORRODED REINFORCED CONCRETE BEAMS UNDER DIFFERENT COOLING METHODS

  • 摘要: 为了探究不同冷却方式下锈蚀钢筋混凝土梁的正常使用极限状态,该文制作了20根混凝土梁。对其进行加速锈蚀试验、火灾试验以及自然冷却和喷水冷却后的静力试验,研究发现,随着损伤程度的增加,试验梁的刚度减小,变形能力下降。以锈蚀率0.15和受火时间120 min为例,喷水冷却下试验梁刚度降幅高达63.6%,相较于自然冷却降幅56.9%更为明显;此外,受弯裂缝宽度相比于未损伤的普通混凝土梁扩大了1.5倍~2.2倍。依据《混凝土结构设计规范》(GB50010−2010),发现挠度计算值与试验值误差较大且计算偏不安全。故对其进行修正,建立了不同冷却方式下锈蚀梁的短期刚度和裂缝宽度的计算公式,利用该文与其他学者的试验数据进行验证。结果表明:计算值与试验值比值均值分别为0.97和1.028,吻合良好,且计算偏安全。

     

    Abstract: In order to investigate the normal service limit state of corroded reinforced concrete beams under different cooling methods, 20 concrete beams were fabricated in this study. They were subjected to accelerated corrosion tests, to fire tests, and to static tests after natural cooling and water spray cooling. The study found that with increasing damage, the stiffness and deformation capacity of the test beams were reduced. For example, with a corrosion rate of 0.15 and a fire time of 120 min, the stiffness of the test beams decreased by 63.6% under water spray cooling, which was more significant compared to the 56.9% reduction under natural cooling; in addition, the width of the bending cracks in the corroded beams was 1.5-2.2 times larger than that of the intact ordinary concrete beams. Based on the “Code for Design of Concrete Structures GB 50010−2010”, it was found that the error between the calculated and measured deflection values was large and the calculation was conservative. Therefore, a correction was made, and formulas for short-term stiffness and crack width of corroded beams under different cooling methods were established. The computational results were verified using experimental data from this study and existing literatures. The results also show that the average ratio of calculated values to experimental values is 0.97 and 1.028, indicating that the analysis results with experimental ones are in a good agreement and, that the calculation is relatively safe.

     

/

返回文章
返回