长期荷载作用下锈蚀栓钉连接件卸载后静力试验研究

Experimental study on static behavior of corroded connectors after long-term actions

通过8个标准连接件的推出试验,研究长期荷载卸载后锈蚀栓钉连接件的静力性能,了解长期荷载与栓钉锈蚀对连接件抗剪承载力、荷载-滑移曲线及变形能力的影响。试验结果表明:推出试验中,栓钉经历了先受压再受拉最后剪断3个受力阶段,栓钉受压处混凝土应变远远高于周边混凝土,随着荷载的增加,连接件刚度处在一个加速退化的状态;腐蚀与荷载存在耦合作用,对于栓钉受拉侧,腐蚀与荷载耦合加速栓钉锈蚀,对于栓钉受压侧,腐蚀与荷载耦合抑制栓钉锈蚀;长期荷载加速初始滑移的发展,但对试件最终滑移量及承载力影响不大,栓钉锈蚀降低试件刚度,加大滑移发展速率,降低极限承载力,对最终滑移量影响显著。最后,通过参数拟合方法建立锈蚀栓钉连接件抗剪承载力及荷载-滑移曲线计算公式,拟合结果表明,计算公式能够较准确地计算锈蚀栓钉连接件的抗剪承载力、滑移终值及荷载-滑移曲线,可为组合结构锈蚀计算提供参考。

Eight push-out specimens of stud connectors were tested to investigate the static performance of corroded stud connectors after long-term actions. The effects of long-term load and corrosion of studs on the shear bearing capacity, load-slip curve and distortion capacity were discussed. The test results show that throughout the push-out test, the studs were subjected to three stress phases of first compression, then tension and finally shear. The concrete strain at the compression of the stud is much higher than that of the surrounding, and as the load increases, the stiffness of the connector is in an accelerated degradation state. The coupling effect of corrosion and load accelerates corrosion at the tension side of the stud, while it inhibits corrosion on the pressure side. Long-term load accelerates the development of initial slip, but it has little effect on the ultimate slippage and bearing capacity of the specimen. With the corrosion of the stud, the rigidity of the specimen and the ultimate bearing capacity reduce, the development rate of slip increases, and the final slippage was influenced significantly. Finally, the shear load capacity and the load-slip curve formula of the corroded stud connector were established by the parameter fitting method. The results show that the fitting formula can be used to calculate the shear bearing capacity, the final slippage and the load-slip curve of corroded stud connectors, which can provide a reference for the calculation of the combined structures.