strengthening of steel bolt connection

huangyhg

strengthening of steel bolt connection
i am currently designing a structure which has an interface with an existing steel frame structure. my assessment showed that the existing steel beam bolt connections need strengthening to support the new structure. please advice on the best way to approach/solve this problem.
you need to identify the weak links to begin.  is the bolt shear, bearing, shear through the connector plates, etc?  once you do this, the answer should shake out.
the bolt is in shear. they are black bolts in double shear installed in 1962.
as jed says, you need to identify which of the design criteria are not met.  but if the issue is purely bolt strength, perhaps replacing the bolts with higher strength bolts would be a solution.  have you identified the grade of the bolts?  if high strength bolts were used, it may also be possible, working space provided, to remove bolts individually, ream the holes, and use larger bolts.  or perhaps the connections can be field welded to provide higher capacity.  a lot of options, depending on the type of connections which were used.