What is one effect of external post-tensioning on cracked bridge members?

• A. Adds preload to close cracks
• B. Increases corrosion rate
• C. Decreases stiffness
• D. Reduces load redistribution

Answer: (A)

External post-tensioning introduces a compressive preload into the member through tendons anchored at the ends. That added compression presses the crack faces together, reducing crack width and keeping the section under compression under service loads. By closing cracks, the member can carry higher loads more reliably and crack growth is slowed, which is the main practical benefit in cracked bridges. The other options don’t describe this immediate effect: corrosion rate depends on environment and protection rather than prestressing; prestressing generally increases stiffness rather than decreases it; and it tends to improve, not reduce, the ability to redistribute loads across cracked regions.