Dynamic Factors Ffor FLS Design of Railway Bridges

[gayanud]

When designing railway bridges it is obvious that dynamic factors should be used for fatigue limit state design. But some argue that dynamic factors should not be taken in to account for the analyses when the FLS design approach is damage calculation method. Any comments please. My argument is either it is simplified or damage calculation, the bridge should be analyzed with loads including dynamic factors. Am I correct?

 

[RUStructural]

Dynamic increase factors should be included. I am not very familiar with the provisions of the AREMA code but, I do know that the AASHTO LRFD Bridge code requires a 15% dynamic increase for fatigue checks. This factor is less than that used for the strength level checks (33% for strength).

 

[gayanud]

Thank You RUStructural for your answer. I am designing according to British method. The British approach for fatigue design was in BS codes and currently the same method is adapted with few modifications in Euro codes. There are two approaches called Simplified and Damage calculation. Do you have any idea? Some designers say the bridge should be analyzed without dynamic factor if the damage calculation method is used for the fatigue design. My opinion, it's a misinterpretation of code. Just want to confirm it from experts. Thanks in advance.