锈蚀焊钉连接件静力性能试验研究

Experimental Study on Static Performance of Corroded Stud Connector

为有效判断组合梁结构的使用寿命和耐久性,给桥梁养护工程师对于钢-混凝土组合梁在服役过程中采取养护措施提供思路,针对钢-混凝土组合梁中焊钉连接件这一关键节点在受到不同程度锈蚀影响下的静力性能进行研究分析。为更好地模拟实际焊钉连接件在服役期的受力状态,采用单侧推出试件进行了试验分析。首先,对比单侧推出试件和《欧洲规范4》推荐的双侧推出试件在静载条件下的试验情况,判断两种试件表观变化和受力状态的区别,由此得到单侧推出试件的可行性和优点。然后,采用恒电流加速锈蚀方法对单侧试件进行了锈蚀处理,基于单侧推出试验研究了不同锈蚀程度下焊钉连接件力学行为变化规律。结果表明:由于双侧试件的4根焊钉连接件并未全部达到极限破坏强度,因此单侧试件推出试验得出的单根焊钉连接件抗剪承载力略大于双侧试件结果,单侧试件得到的荷载-滑移曲线发展趋势与双侧试件一致,单侧试件可用于研究焊钉连接件静载破坏力学性能;锈蚀会导致焊钉连接件变形量、屈服强度和极限抗剪承载力等力学性能下降,造成复合结构性能的退化和耐久性的降低;焊钉连接件极限承载力降低速率大于锈蚀增大速率。最后,结合试验结果拟合了系数曲线,提出了锈蚀焊钉连接件抗剪承载力计算公式。

In order to effectively analyze the service life and durability of composite beam structures,and provide idea for bridge maintenance engineers to take maintenance measures during the service process of steel-concrete composite beams,the static performances of the key node of stud connector in steel-concrete composite beams under different corrosion degrees are studied.To better simulate the stress state of actual stud connector during service life,the experimental analysis is conducted by using single-side push-out specimen.First,the test conditions of double-side push-out specimens recommended in‘Eurocode 4’and single-side push-out specimens under static load are compared,the differences in apparent changes and stress states between the 2 kinds of specimens are determined,thus the feasibility and advantages of single-side push-out specimen are obtained.Then,corrosion of the single-side specimen is treated by using constant current accelerated corrosion method,the mechanical behavior changes of the stud connector under different corrosion degrees are studied based on single-side push-out test.The result shows that(1)Due to the fact that not all 4 stud connectors of the double-side specimen have reached their ultimate failure strength,the shear bearing capacity of the single stud connector obtained from the push-out test of the single-side specimen is slightly greater than that of the double-side specimen.The development trend of the load-slip curve of the single-side specimen is consistent with that of the double-side specimen,and the single-side specimen can be used to study the static load failure mechanical properties of the stud connectors.(2)The corrosion will lead to the decline of the mechanical properties such as deformation,yield strength and ultimate shear capacity of the stud connectors,resulting in degradation of performance and durability of the composite structure.(3)The reduction rate of the ultimate bearing capacity of the stud connector is greater than the increase rate of corrosion.Finally,combining with the test result,the coefficient curve is fitted and the calculation formula of shear capacity of corroded stud connector is put forward.