The fatigue life of prestressed concrete beams, subjected to cyclic bending, mainly depends on the fatigue behaviour of the embedded prestressing strands. An evaluation of international fatigue test results revealed a reduced fatigue life of embedded strands in prestressed concrete beams compared to single strands in air. The reduced fatigue life can be explained by specific influences and fatigue processes caused by the built-in conditions of strands. Due to the lack of basic understanding, systematic investigations are currently carried out to identify, quantify and describe different influencing parameters and fatigue processes as well as to better understand and determine the fatigue behaviour of strands in pre-tensioned concrete beams. In this article, the experimental investigations regarding the fatigue life of strands embedded in concrete are presented. Within cyclic uniaxial tensile tests on strands in air and strands embedded in concrete, the influence of fretting fatigue processes and friction stresses between the outer wires of strands and the surrounding concrete was determined.

中文翻译：

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嵌入混凝土中的预应力钢绞线的循环拉伸试验

承受循环弯曲的预应力混凝土梁的疲劳寿命主要取决于预应力预应力钢绞线的疲劳行为。对国际疲劳试验结果的评估表明，与空气中的单股相比，预应力混凝土梁中的嵌入式股的疲劳寿命降低。疲劳寿命的降低可以用特定的影响和由钢绞线的内在条件引起的疲劳过程来解释。由于缺乏基本认识，目前正在进行系统调查以识别、量化和描述不同的影响参数和疲劳过程，以及更好地理解和确定预应力混凝土梁中钢绞线的疲劳行为。在本文中，介绍了关于嵌入混凝土中的钢绞线疲劳寿命的实验研究。在空气中的钢绞线和嵌入混凝土中的钢绞线的循环单轴拉伸试验中，确定了微动疲劳过程和钢绞线外线与周围混凝土之间摩擦应力的影响。