Final answer:
The minimum radius for bending structural tubes is not specified within the references, but it is influenced by the elastic resistance to bending and inextensibility constraint, with practical guidelines often suggesting that it should be at least equal to the tube diameter.
Step-by-step explanation:
The minimum radius of any bend in structural tubes is not explicitly detailed in the provided references. However, when designing bends in structural tubes, engineers must consider factors such as the bending modulus, which characterizes the elastic resistance to bending, ensuring that the deformation does not result in changes to the overall volume or compromise the structural integrity of the material. The inextensibility constraint is also considered, keeping the rod length unchanged after bending. Practical engineering standards, building codes, and manufacturing specifications typically determine the minimum bend radius for specific materials and applications. In engineering practice, the bend radius is often related to the thickness of the tube; for example, a common guideline is that the minimum bend radius should be at least equal to the tube diameter.