ABSTRACT
Strengthening can often be used as a cost-effective alternative to replacement or posting. Several of the strengthening techniques, however, are equally effective for long-span bridges. The techniques used for strengthening, stiffening, and repairing bridges tend to be interrelated so that, for example, the stiffening of a structural member of a bridge will normally result in its being strengthened also. The chapter provides information an engineer can use to resolve the majority of bridge strengthening problems. Examination of National Bridge Inventory bridge records indicates that the bridge types with greatest potential for strengthening are steel stringer, timber stringer, and steel through-truss. Lightweight deck replacement can be used conveniently in conjunction with other strengthening techniques. A successful method of strengthening reinforced concrete beams has involved the attachment of a steel channel to the stem of a beam. Some strengthening techniques included steel-cover-plating beam members as well as truss members.
