Cantilever of a box girder

[Catjacob]

I got a compsoite box girder (steel closed box with concrete slab on top) which may cantilever from the pier at about 6m.

Could any body tell me how to minimize the effects of deflection and vibration. Can I install dampers or struts of which the ends are loaded against the tip of the box and the diaphragm of the box over the pier??

 

[bridgebuster]

You're not providing much information.

Anyway, one way to reduce deflection of the cantilever is to make the section stiffer.