CAFT defines the permissible stress range for what fatigue life?

CAFT defines the permissible stress range for what fatigue life?

• A. Finite life
• B. Infinite life
• C. Short life
• D. Infinite fatigue life

Answer: (D)

The main idea being tested is that the permissible stress range defined by CAFT is tied to infinite fatigue life. In fatigue analysis, life is typically discussed in terms of how many cycles a member can endure before a failure occurs. Infinite fatigue life means the stress range is low enough that, in theory, the component would not fail no matter how many loading cycles it experiences. CAFT uses this criterion as the baseline for setting allowable stress ranges, aiming for long-term durability of bridge members. So, the permissible stress range is defined for infinite fatigue life because it establishes a conservative, long-term limit: the stress amplitude you allow should not cause fatigue failure over an unlimited number of cycles. Finite life or short life criteria describe scenarios where failure is expected within a limited number of cycles, which is not the standard basis CAFT uses for determining the baseline allowable stress range.

The main idea being tested is that the permissible stress range defined by CAFT is tied to infinite fatigue life. In fatigue analysis, life is typically discussed in terms of how many cycles a member can endure before a failure occurs. Infinite fatigue life means the stress range is low enough that, in theory, the component would not fail no matter how many loading cycles it experiences. CAFT uses this criterion as the baseline for setting allowable stress ranges, aiming for long-term durability of bridge members.

So, the permissible stress range is defined for infinite fatigue life because it establishes a conservative, long-term limit: the stress amplitude you allow should not cause fatigue failure over an unlimited number of cycles. Finite life or short life criteria describe scenarios where failure is expected within a limited number of cycles, which is not the standard basis CAFT uses for determining the baseline allowable stress range.