Although pretensioned concrete structures have increasingly been used worldwide, a number of design issues need to be addressed to further improve the structural performance. Transfer length of pretensioned members was investigated with several test variables in this study by adopting various sensing technologies including the Smart Strands with embedded fiber optic sensors. The effect of increased strength in 2360 MPa high-strength strand on the transfer length was also analyzed. Representative provisions widely used in design were compared with the test results for consistency and appropriate conservatism. The strain distribution required for the transfer length depended partly on the type and location of sensors, which suggests the challenges associated with reasonable determination of the transfer length. According to the results of the analysis, the predictive equation in ACI 318 was relatively accurate and conservative under various conditions including high-strength strands. However, the transfer lengths based on the strand strains rather than the conventional surface strains of concrete require further investigation depending on the bonding behavior between the strand and the surrounding concrete inside a member. Thus, this study also introduces a new sensing technology utilizing the Smart Strand to reliably measure the strain distribution along a strand.

中文翻译：

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使用各种传感技术测量预应力混凝土中的传递长度

尽管预应力混凝土结构在世界范围内越来越多地使用，但仍需要解决许多设计问题以进一步提高结构性能。在本研究中，通过采用各种传感技术（包括带有嵌入式光纤传感器的智能绞线），通过几个测试变量研究了预拉伸构件的传递长度。还分析了 2360 MPa 高强度钢绞线强度增加对转移长度的影响。设计中广泛使用的代表性条款与测试结果进行了比较，以确保一致性和适当的保守性。传输长度所需的应变分布部分取决于传感器的类型和位置，这表明与合理确定传输长度相关的挑战。根据分析结果，ACI 318中的预测方程在包括高强度钢绞线在内的各种条件下都比较准确和保守。然而，基于钢绞线应变而非混凝土传统表面应变的传递长度需要进一步研究，具体取决于钢绞线与构件内部周围混凝土之间的粘合行为。因此，本研究还引入了一种新的传感技术，利用智能钢绞线可靠地测量沿钢绞线的应变分布。基于钢绞线应变而非混凝土传统表面应变的传递长度需要进一步研究，具体取决于钢绞线与构件内部周围混凝土之间的粘合行为。因此，本研究还引入了一种新的传感技术，利用智能钢绞线可靠地测量沿钢绞线的应变分布。基于钢绞线应变而非混凝土传统表面应变的传递长度需要进一步研究，具体取决于钢绞线与构件内部周围混凝土之间的粘合行为。因此，本研究还引入了一种新的传感技术，利用智能钢绞线可靠地测量沿钢绞线的应变分布。