Abstract In tall and light structures, such as transmission towers, wind turbines, and light-gauge steel structures, there is an increasing application of pile cap with helical pile foundation systems to resist the uplift loads due to the effects of windstorms and earthquakes. There is a lack of knowledge, published literature, or analysis methods to account for the effects of the pile cap, helical pile group, and soil interactions on the holistic response of the foundations, particularly, for the load conditions creating net uplift loads. In the lack of such, discrete modeling approaches are frequently employed in practice. These approaches isolate each system component and analyze them individually, neglecting the interactions between them. In an attempt to bridge this knowledge gap, this study proposes a system-level modeling methodology for the holistic analysis of pile cap systems in dry soil and static load conditions, while accounting for the effects of interactions between system components and the inherent material nonlinearities. The methodology employs a three-stage process in which the material and interaction properties are calibrated with the experimental benchmark specimens. The failure mechanisms are also experimentally verified based on the relative displacement of the piles. Important modeling considerations are discussed, and experimental benchmark specimens are provided to assist practitioners in accurately performing system-level analyses. The effectiveness of the proposed methodology is discussed, and the responses obtained, including the load–displacement responses, load capacities, and failure modes, are compared with those obtained from the discrete modeling approaches. The results demonstrate that discrete modeling approaches significantly underestimate the load capacity while not accurately predicting the governing behavior and the failure modes.

中文翻译：

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用于捕获桩帽、螺旋桩群和在隆起荷载下的土壤相互作用的系统级建模方法

摘要 在输电铁塔、风力发电机组、轻型钢结构等高大轻型结构中，越来越多地采用带螺旋桩基础系统的桩帽来抵抗风暴和地震引起的上拔荷载。缺乏知识、已发表的文献或分析方法来说明桩帽、螺旋桩组和土壤相互作用对地基整体响应的影响，特别是对于产生净抬升荷载的荷载条件。在缺乏这样的情况下，在实践中经常采用离散建模方法。这些方法隔离每个系统组件并单独分析它们，忽略它们之间的相互作用。为了弥合这一知识鸿沟，本研究提出了一种系统级建模方法，用于在干土和静载荷条件下对桩帽系统进行整体分析，同时考虑系统组件和固有材料非线性之间相互作用的影响。该方法采用三阶段过程，其中材料和相互作用属性用实验基准样本进行校准。破坏机制也基于桩的相对位移进行了实验验证。讨论了重要的建模注意事项，并提供了实验基准样本，以帮助从业人员准确执行系统级分析。讨论了所提出方法的有效性，并获得了响应，包括负载位移响应、负载能力和故障模式，与从离散建模方法获得的那些进行比较。结果表明，离散建模方法显着低估了负载能力，而不能准确预测控制行为和故障模式。