UHPC中短栓钉抗剪性能试验及理论分析

为深入研究超高性能混凝土（Ultra-high Performance Concrete，UHPC）中短栓钉的抗剪性能，提出精细化的计算理论和方法，指导工程设计，共完成9个静力推出试验。试件参数包括短栓钉直径、界面处理情况以及加载方式。根据试验受力模式，提出了一种三维精细有限元分析模型，利用ABAQUS显式分析方法，探讨焊缝形式、短栓钉直径、短栓钉高度、UHPC强度等参数对UHPC中短栓钉抗剪性能的影响。最后结合试验数据及有限元分析结果提出UHPC中短栓钉荷载-滑移全曲线实用经验公式和抗剪承载力计算公式。试验及分析结果表明：短栓钉抗剪承载力主要受短栓钉直径和焊缝形式的影响，随短栓钉直径的增大而提高，有限元中模拟焊缝相比于不模拟焊缝时短栓钉抗剪承载力提高48%~93%；短栓钉抗剪刚度主要受短栓钉直径和界面处理情况的影响，界面黏结将提高抗剪刚度；加载方式（单调加载和循环加载）、短栓钉高度和UHPC强度对短栓钉抗剪性能影响较小；2种不同直径短栓钉最大滑移均不超过4 mm，设计时可按照弹性连接件设计方法计算；收集的国内外68组有效试验数据与理论计算结果吻合度较高；建议取0.3P_u~0.4P_u（短栓钉抗剪承载力）处的割线刚度平均值作为UHPC中短栓钉抗剪刚度，抗剪刚度试验值与理论计算结果对比表明该方法具有较高的精度。

Performance of Experimental and Theoretical Analysis on Shear Short Headed Studs Embedded in UHPC

To investigate the shear performance and mechanism of short headed studs embedded in UHPC further and propose a unified calculation theory and method to guide engineering design, nine static push-out specimens were conducted, and test parameters such as stud diameter, interface treatment, and loading modes were analyzed. Based on the experimental damage pattern, a refined finite element model is proposed to analyze the influence on the stud shear capacity of parameters such as weld, stud diameter, stud height, and UHPC strength using the ABAQUS explicit dynamic analysis method. A practical calculation formula for the load-slip curve and a formula for the shear capacity of short studs are proposed. The experimental and analytical results indicate the following:The shear capacity of short studs is mainly affected by the diameter of the studs and the form of welds, and enhances significantly with increase in the diameter of the studs. Meanwhile, the shear capacity of short studs with welds increases in the range 48%-93% compared to that of short studs without weld. The shear stiffness of short studs is remarkably influenced by the stud diameter and interface treatment. The enhancement of the interfacial bond can effectively improve the shear stiffness of short studs. However, other parameters, including loading mode (monotonic and cyclic loading modes), short stud height, and UHPC strength, barely influence the shear performance of short studs. The maximum slip value of the two types of studs with different diameters is 4 mm at most; this value can be designed according to the elastic connector design method. The theoretical calculated results are in good agreement with the experimental results of 68 specimens at home and abroad. Finally, the average secant stiffness at 30% to 40% of the shear capacity of the load-slip curve is recommended as the shear stiffness of short studs. A comparison between the theoretical and test results shows that the proposed method achieves higher accuracy.