Reliability based constant amplitude fatigue limit of shear connection with headed studs for single or multi-axis fatigue loading

用于单轴或多轴疲劳载荷的带头螺柱剪切连接的基于可靠性的等幅疲劳极限

• 批准号: 512645468
• 负责人: Professor Dr.-Ing. Karsten Geißler
• 金额: --
• 依托单位: Lehrstuhl für Metallbau
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/512645468?language=en
• 关键词: Reliability; based; constant; amplitude; fatigue

In the construction of many of the new large composite bridges planned for the coming decades, the longitudinal shear transfer between concrete and steel building components is ensured by headed studs. These are subjected to fatigue not only in the main load-bearing direction, as was the case in the past, but also in the transverse direction. In highway bridges, the number of load cycles for the structural members bearing in the transverse direction is many hundreds of millions, even though the stress ranges for highway bridges often are not very high. Thus, a fundamental scientific treatment of the following two issues is imperative:- Theoretical and experimental justification of a hitherto completely unexplored endurance limit for fatigue-stressed shear connectors with headed studs, including the required safety margin for design, - Analysis of the stress conditions under multiaxial fatigue loading for the headed studs and consequences for design. Since few experimental results exist internationally for the fatigue limit under shear loading of headed studs, such fatigue tests with up to 30 million load cycles are mandatory. Because of the high number of load cycles and the resulting test effort, the test program required for statistically valid results can only be reasonably implemented at two universities. In order to avoid the disadvantages of the push-out tests commonly used so far, a novel test rig is designed and tested in parallel, which also allows multiaxial fatigue loading for dowel groups. Furthermore, PAUT-TFM, a new method for non-destructive testing in civil engineering, will be further developed in such a way that the cracks originating from the weld collar of the headed studs can be detected at an early stage and theoretically evaluated with regard to the delimitation of crack initiation and crack growth phases, which will be quite different than previously known for the low stress ranges investigated here. The tests are supplemented by numerical investigations, which, based on previous investigations, focus in particular on the low load level typical of road bridges. Particular attention is paid to the local stresses on the concrete that occur at this load level and their effects on the stress peaks occurring on the outer and inner edge of the weld collar of the studs.Probabilistic fatigue analysis is used to justify the required safety margin in design, i.e. the design value of the fatigue limit, taking into account the distributions of the input parameters. To round off the project, three large bridges of current design will be used to verify by calculation and measurement at what level the global and local fatigue stresses of the headed studs lie in comparison to the justified design value of the fatigue limit.

在未来几十年计划的许多新的大型复合桥的建设中，由头螺柱确保了混凝土和钢结构组件之间的纵向剪切转移。这些不仅会在主要负载方向上疲劳，而且还会像过去一样，而且在横向方向上也会疲劳。在高速公路桥梁中，即使高速公路桥的应力范围通常不是很高，沿横向方向的结构构件的负载周期数量为数亿。因此，必须对以下两个问题进行基本科学治疗： - 迄今为止，迄今为止，迄今未探索的耐用耐力极限，用于带有头螺柱的疲劳应力剪切连接器，包括设计的所需安全保障， - 分析用于设计螺柱的多轴疲劳下的压力条件和后果。由于在头螺柱的剪切负荷下，国际上很少有实验结果在国际上存在，因此必须进行高达3000万个负载周期的疲劳测试。由于负载周期的数量很高和结果测试工作，因此只能在两所大学中合理地实施统计上有效结果所需的测试程序。为了避免到目前为止通常使用的推出测试的缺点，并平行设计和测试了新型的测试钻机，这也允许为销钉组进行多轴疲劳负荷。此外，PAUT-TFM是一种在土木工程中进行无损测试的新方法，将进一步开发，以至于可以在早期阶段检测到来自头螺柱的焊缝的裂缝，并理论上对裂纹开始和裂纹生长阶段的界定界定的划定相比，在这里对低压力进行了不同的划定，在此期间对裂纹的划界进行了不同。这些测试补充了数值研究，基于先前的研究，该测试尤其关注典型的道路桥的低负荷水平。特别注意在该负载水平上发生的混凝土的局部应力，以及它们对螺柱焊缝焊缝外部边缘和内部边缘发生的应力峰的影响。培养基疲劳分析用于证明设计中所需的安全余量合理，即疲劳限制的设计值，考虑到输入参数的分布。为了解决该项目，与疲劳限制的合理设计值相比，标头螺柱的全球和局部疲劳应力在何种水平上，将使用三个当前设计的大桥来验证。