Steel Box Girder Access Opening
Steel Box Girder Access Opening
(OP)
The DOT we're designing a steel box girder bridge for states that access opening in the bottom flange shall not be spaced more than 300' apart. We have a 3-span bridge with a total length of 600'. The DOT won't let us put the access opening over traffic in a positive moment region so it's going to end up being in the compression zone near the pier. Has anyone designed the area around this opening in the compression zone? I assume that some kind of additional ring plate or longitudinal stiffeners will be required. Is there any literature for this situation? Thanks!





RE: Steel Box Girder Access Opening
I can't imagine trying to put an access in the bottom flange except at the abutments. Near the piers you would have very thick bottom plates and probably long. stiffeners.
Is the web an option for you?
RE: Steel Box Girder Access Opening
RE: Steel Box Girder Access Opening
The collar was dimensioned to partially substitute for the material lost due to the opening, as detailed calculations for the section were done. As the opening was offset from the pier by 8', the negative moment could be carried by weakened section without reinforcing ring, but one was provided to minimize change in the stress level.
RE: Steel Box Girder Access Opening
Did you perform a FEM analysis to check for buckling? I guess that's our biggest concern.
RE: Steel Box Girder Access Opening
Did you find any literature regarding this topic? I'm running into the same situation with FDOT. Similar bridge length as yours 185-245-185.
RE: Steel Box Girder Access Opening
RE: Steel Box Girder Access Opening
I will strongly encourage performing FEM analyses of the area, as simplified model is easy to construct and assess.