Deck plate fatigue detail

[Edu09]

Hi all,

I've attached a sketch regarding this detail, it's a T-stiffener welded to the underside of the steel deck plate of a bridge. The structure is a rail bridge so I've calculated the stresses in the section due to the live loading(LM71) and I am treating 0 live load as the minimum for the stress range. My question for the location of the welds, do I take the compressive stress in the plate as the maximum for my fatigue stress range? This is what I think but the tension stress in obviously larger.

Anyway, as always, any and all thoughts and insights gratefully received.

Thanks

 

[Shu Jiang PEng SE]

The T-stiffener and part of the steel deck plate work together as a unequal flange "W" beam is to be taken flexural bending. The stress of the weld between the stiffener and the deck plate is not the same as the compression stress of the deck plate. It is should be calculated per the formula as shown int picture.

Please note that the weld may also experience stress due to the wheel load applied directly above the web.

 

[Edu09]

Thanks for your help Jiang.