Prestressed Concrete Stay
Definition
A structural cable or member in which high-strength steel tendons are tensioned within a concrete encasement. The Ponte Morandi stays used this hybrid form, which made tendon inspection difficult without destructive testing.
- Structure type
- Tensioned steel tendons within concrete encasement
- Function
- Structural cable or member
- Notable case
- Ponte Morandi
- Inspection challenge
- Tendon condition hard to assess non-destructively
Common questions
Why is this hybrid stay design harder to inspect than an exposed steel cable?+
The concrete encasement conceals the steel tendons from direct visual inspection, so corrosion or tendon failure developing inside the encasement can progress unseen unless the investigator uses invasive sampling or specialised non-destructive methods, unlike an exposed cable stay whose surface condition can be checked visually.
What role did the encasement play in the Ponte Morandi investigation?+
Investigators found that corrosion had developed within the tendon-concrete interface where moisture had penetrated, and because the damage was hidden inside the encasement it went undetected for years despite routine inspection, making the concealment itself a contributing factor examined in the failure analysis.
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