拔出破坏的钢混组合结构栓钉连接件承载力的分析方法

Analysis Method of Bearing Capacity of Stud Connector in Steel-concrete Composite Structures Under Push-out Failure

当栓钉长径比较小时,栓钉连接件容易发生拔出破坏,目前这种非材料破坏的失效形式的承载力主要通过试验确定。为了扩大有限元方法的应用,提出在有限元分析中以栓钉端头处的混凝土压应变为控制变量判断栓钉是否发生拔出破坏的分析方法,并确定其承载力。首先,采用ABAQUS软件建立标准推出试验的有限元模型,并将有限元计算值与文献实测值和规范计算值进行对比,其结果表明误差均在10%以内,验证了有限元模型的正确性。然后,结合提出的考虑栓钉拔出破坏的分析方法分析了栓钉的长度和直径对承载力的影响。最后,给出了栓钉拔出破坏的承载力计算公式。结果表明:栓钉与混凝土之间的绑定约束是面面接触方式的刚度的上限;混凝土强度越低越容易发生拔出破坏,规范中规定的栓钉长径比大于4以防止拔出破坏是偏于不安全的;由栓钉直径的增大而引起的连接件承载力的提高程度不受混凝土强度的影响,当栓钉直径在10～22 mm范围内以3 mm的增量增大时,承载力提高约42%、31%和35%;当栓钉直径大于16 mm时,《钢结构设计规范》计算的承载力值偏大,建议按Eurocode4规范进行设计;提出的栓钉拔出破坏的判断方法和承载力计算公式经规范计算值验证是合理可行的。

Push-out failure is easy to happen in stud shear connector with small length-diameter ratio of stud.At present,the bearing capacity of push-out failure mode is usually determined by test.In order to extend the application of finite element analysis,the compression strain of concrete near the stud end was taken as a control variable to judge whether the push-out failure happens.Firstly,ABAQUS software was used to create finite element model of standard push-out test.The results were compared with both the reference and design codeand the correctness of finite element model was verified.Then,the influences of length and diameter of stud on bearing capacity were analyzed combined with the method of analyzing the push-out failure.Lastly,the calculation formula of bearing capacity with push-out failure was given.Results showed that the tie constraint between stud and concrete was the upper limit of stiffness for surface-to-surface interaction.Push-out failure was prone to happen with lower concrete strength and it was unsafe to just restrict the length-diameter ratio of stud larger than four to avoid pull-out failure in design code.The degree of increase of bearing capacity caused by the diameter of stud was not affected by concrete strength.When the diameter of stud increased from 13 mm to 22 mm with an increment of 3 mm,the bearing capacity increased by 42%,31%and 35%,respectively.Eurocode4 was suggested to be followed for design when the diameter of stud was larger than 16 mm,because the value calculated from Code for Design of Steel Structure was a little large.The judgment method and calculation formula of bearing capacity proposed for push-out failure were reasonable and verified by calculated value of design code.