纤维高强混凝土干接缝剪切性能试验研究

节段预制匹配梁混凝土干接缝键齿受力后易沿键齿根部产生斜裂缝，并发生沿键齿根部脱落的脆性破坏，在混凝土中掺加纤维可改善干接缝剪力键受力性能。考虑纤维长度、纤维形状、纤维种类及纤维体积率4种影响因素，制作了4组9对干接缝剪力键试件进行直剪试验，得到了以上4个因素对纤维高强混凝土干接缝剪切行为和抗剪强度的影响规律。结果表明：与未掺加纤维的高强混凝土相比，纤维高强混凝土干接缝的开裂剪应力、极限剪应力和延性均有所提高，开裂剪应力平均提高了48.1%，极限剪应力提高了26.0%，延性指标提高了24.4%；在一定范围内，纤维高强混凝土干接缝的极限剪应力随着纤维长度的增长和纤维体积率的增大而增大；纤维混凝土可以增强干接缝的极限剪应力，端钩型纤维对干接缝极限剪应力提升的效果明显大于波浪型和平直型；同时，归纳了既有干接缝承载力计算公式，利用既有试验数据对不同公式的承载力计算值进行了对比分析，发现各公式对试件承载力的预测值与侧向预压应力有关，其中Rombach公式计算值与试验值吻合最好，但离散度较大。试验结果可为今后纤维高强混凝土干接缝剪切行为和抗剪强度的研究提供数据支持。

Experimental Investigation on Shear Performance of Fiber-reinforced High-strength Concrete Dry Joints

Dry joint shear keys of a precast concrete segmental girder are prone to diagonal cracks and brittle failure along the root of the key, and adding fiber can improve their mechanical properties. Considering the four influencing factors of fiber length, fiber shape, fiber type, and fiber volume ratio, four groups of nine pairs of dry joint shear key specimens were cast and tested. The effects of the above four factors on the shear performance and shear capacity of fiber concrete dry joints were obtained. An analysis of the test data shows that compared with high-strength concrete without fiber, the cracking load, ultimate load, and ductility of fiber-reinforced high-strength concrete joints improved. The average cracking shear stress is increased by 48.1%, average ultimate shear stress is increased by 26.0%, and average ductility is increased by 24.4%. Within a certain range, the ultimate shear stress of the dry joints of fiber-reinforced high-strength concrete increases with the increase in fiber volume ratio, the increase in the fiber length in fiber-reinforced concrete can enhance the ultimate shear stress of dry joints, and the end hook type fiber has a markedly greater effect on the ultimate shear stress than the two other types. Subsequently, the existing formula of the shear capacity of dry joints was summarized. Based on the existing test data, the calculation values of different formulas were compared and analyzed, and it was found that the calculated values of each formula are related to the lateral precompression stress. The calculated values of Rombach agree well with the experimental value, but the dispersion is significant. The results of this experiment provide data to support future research on the shear behavior and shear strength of fiber-reinforced concrete dry joints.