What is the significance of a low-relaxation strand in post-tensioning applications?

In post-tensioning applications, a low-relaxation strand is significant because it results in lower stress losses over time. When post-tensioning strands are installed, they experience an initial tension that must be maintained throughout the life of the structure. Over time, the stress in these strands can decrease due to a phenomenon known as relaxation, where the tension reduces as the material settles or adjusts under load.

Low-relaxation strands are engineered to minimize this loss of stress, which means the initial tension applied to the strands remains more consistent over time. This characteristic is crucial for maintaining the structural integrity and performance of post-tensioned concrete elements, as it helps ensure that the desired level of prestress is retained. By reducing stress losses, these strands contribute to the longevity and effectiveness of the post-tensioning system, preventing excessive deflections and maintaining overall stability in structural applications.