This study is concerned with the problem of energy piles subjected to constant axial load and temperature variation uniform over the cross-section. In the first part of this paper, equations for the analysis of energy piles based on elastic theory and the load-transfer approach are described. Closed-form solutions are derived for a few simple cases. It is observed that temperature variation effects can be conveniently expressed by a factor of thermally imposed strain. In the second part of the paper, a study on the effect of the non-linearity of reinforced concrete on the performance of energy piles under tension is described. A newly developed finite-element model that is within the framework of the load-transfer approach is employed to simulate the response of a pile subjected to thermomechanical loads in isolated as well as in piled raft foundations. The results suggest that the performance of the structure is strongly affected by concrete post-cracking behaviour. Nevertheless, piles can accommodate thermally imposed strains if the ductility capacity is provided. The outcomes of this study may be combined with the knowledge of non-linear behaviour of soil–pile interfaces for a more rational performance-based design approach toward energy piles.

中文翻译：

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能量桩的热应力分析

这项研究涉及能量桩在横截面上承受恒定轴向载荷和温度变化均匀的问题。在本文的第一部分中，描述了基于弹性理论和载荷传递方法的能量桩分析方程。封闭式解决方案是针对一些简单情况得出的。可以看出，温度变化的影响可以方便地用热应变因子来表示。在本文的第二部分，描述了钢筋混凝土非线性对张力下能量桩性能的影响的研究。在载荷传递方法的框架内，使用一种新开发的有限元模型来模拟在隔离以及桩筏基础中桩承受热机械载荷的响应。结果表明，混凝土的龟裂后行为会严重影响结构的性能。但是，如果提供了延展能力，则桩可以承受热施加的应变。这项研究的结果可能与土-桩界面的非线性行为知识相结合，从而为能量桩提供了一种更为合理的基于性能的设计方法。