超高性能混凝土组合桥面板集群化短焊钉抗疲劳特性

Anti-fatigue Characteristics of Short Grouped-stud in Ultra-high Performance Concrete Composite Bridge Decks

摘要:

进行4个单钉和2个群钉疲劳推出试验，将短焊钉疲劳寿命与国内外规范中的焊钉S?N曲线进行比较，并结合塑性损伤有限元模型展开分析。结果表明：短焊钉疲劳破坏表现为根部剪断和周围超高性能混凝土（UHPC）局部压溃；集群化短焊钉疲劳寿命较单钉减少26.9%，在疲劳加载过程中抗剪刚度退化显著快于单钉，当加载次数达到疲劳寿命的12.0%附近时，抗剪刚度比减小至16%左右；AASHTO规范有较大的安全储备，相比之下日本规范（JSCE）与试验结果最为接近，安全富余较少。此外，疲劳荷载下集群化短焊钉根部循环应变幅大于单钉，而且周边UHPC的塑性损伤累积分布更大。

Abstract:

Four single-stud and two grouped-stud fatigue push-out tests were conducted. The fatigue test results of studs were compared with the stud fatigue S-N curve in domestic and international codes， and the finite element analysis based on material plastic damage model was done. It is shown that： the stud root fracture and local UHPC crush around the stud root are the main failure mode； compared with single-stud specimen， the fatigue life of grouped-stud specimen is reduced by 26.9%， and the shear stiffness of grouped-stud specimen degrades more rapidly during cyclic loading； particularly， the stud shear stiffness ratio decreases to 16% when loading cycles reach 12.0% of fatigue life； the AASHTO based evaluation has the largest safety redundancy among the codes while the JSCE based evaluation is closest to the test results but with a low level of safety redundancy. In addition， the finite element analysis results show that the maximum cyclic strain amplitude at stud root obtained from grouped-stud model is larger than that obtained from single-stud model， and the plastic accumulation damage of UHPC around stud root in grouped-stud model is severer than that in single-stud model.