配置500MPa钢筋后张有黏结预应力混凝土梁不同位置处裂缝宽度研究

Research on crack width at different locations of post-tensioned bonded prestressed concrete beams with 500 MPa steel bars

以8根配置500MPa钢筋后张有黏结预应力混凝土梁的弯曲裂缝宽度试验为基础,对不同位置处的裂缝宽度进行统计分析,得到各位置处的短期裂缝宽度扩大系数,比较了不同位置处的裂缝宽度关系;根据试验结果并收集整理相关文献试验数据,建议了不同位置处裂缝宽度换算的计算式。结果表明:各位置处的裂缝宽度均服从正态分布,各位置处的短期裂缝宽度扩大系数基本相同;在梁侧面,预应力筋重心高度处裂缝宽度小于纵向受拉非预应力筋重心高度处裂缝宽度;在梁受拉底面,当裂缝量测点至最近的纵向受拉非预应力筋重心的距离较小时,纵向受拉非预应力筋对量测点处的裂缝具有较好的约束作用;建议计算式可以较好地对不同位置处裂缝宽度进行换算。

On the basis of flexural crack width test of eight post-tensioned bonded prestressed concrete beams with 500MPa steel bars, statistical analysis of crack width at different locations was conducted and the short-term magnifying coefficients of crack width at different locations were calculated. Crack widths at different locations were compared. According to the test results and other research results, the formulas for the conversion of crack width at different locations were proposed. Results show that crack width at different locations basically follow the normal distribution. The short-term magnifying coefficients of crack width at different locations are almost equal. Side crack width at the center of prestressing steel bars is less than that at the center of tensile non-prestressing steel bars. When the distance between the crack measuring points of tensile bottom surface and the nearest center of tensile non- prestressing steel bars is small, the cracks at the measuring points can be well restrained by the tensile non- prestressing steel bars. The formulas suggested in this paper can be used to convert crack width at different locations with good accuracy.