Document Information

Document Type: FAQ

Product(s): LEAP BRIDGE STEEL

Version(s): All

Original Author: Bentley Technical Support Group -VM

QUESTION: How the changes in load factors for Fatigue load combinations is handled?

ANSWER:

The Gamma LL for Fatigue load combination is set inside the steel designer and there is no user control except two places. One, user can set the member as fracture critical in Member Definition window.

And second, user can set the ADDT available in Design Options such that the it can influence in deciding on using Fatigue I or II.

If the member is fracture critical automatically, Fatigue I limit state is used.

If the ADDT_SL is greater than ADDTSL for 75 years, Fatigue I limit state is used.

Otherwise, Fatigue II limit state is used.

If the code is 7^th ed, gammaLL for Fatigue I is set as 1.5 and for 8^th and higher, 1.75 is used.

If the code is 7^th ed, gammaLL for Fatigue II is set as 0.75 and for 8^th and higher, 0.8 is used.