Avoiding deflection in a rail when the bridge is already installed with a permissible deflection

[jor1492]

Hi all,

Currently I have a Gantry (Bridge) already installed with a permissible deflections by the settlement of the structure . Above this structure I will install a shuttle conveyor, Therefore the rail of this machine will present unacceptable deflections that I will require to correct, in this moment maximum deflection is 40mm. My idea is install shims (filler metal plates) under the beam supporting the rail for the correct raising.
Is there a limitation regards the installation of shims for this kind of system, like constraints in the shim size by dynamic loads or some code or good practice document regarding this issue?

I am aware that this mistake is by the incorrect construction/installation process. I know that this structure to avoid the deflection needs a prior deformation to counter the deformation by settlement. So my other question: Is this information, about prior deformation, regularly given by the designer team or fabricator of the structure?

Thanks in advance.

 

[BridgeSmith]

Any bolts passing through the shims ("filler plates" in the AASHTO bridge design spec) will have a reduced shear capacity. The reduction for a 40mm shim/filler will be substantial for smaller bolts (1" diameter or less).