Increased demand for higher legal loads and permit overloads on the nation's highway system necessitates the strengthening of a large number of existing short and medium span bridge structures. frequently, the strengthening of bridge superstructures goes hand in hand with rehabilitation measures of the bridge deck and the road surface, such as structural concrete overlays or widening measures to accommodate additional traffic lanes. as part of an ongoing research project with the california state department of transportation, a 12 ft wide, 60 ft long section of an existing 25 year old cast-in-place reinforced concrete t-girder bridge was brought from near fresno, california to the charles lee powell structural systems laboratory at the university of california, san diego, for full scale investigation of different repair and strengthening measures. the bridge deck was rehabilitated by a full depth structural concrete overlay and testedunder simulated service and overloads. upon completion of the overlay tests to the flexural yield limit state, the flexural cracks of the bridge girder were repaired by epoxy injection. two types of strengthening measures were subsequently investigated, namely the more popular external post-tensioning and a new innovative approach in which a prestressed high strength precast concrete panel was added to the existing bridge girder in the form of a thin bottom soffit. priorand subsequent to the implementation of the repair and strengthening measures, forced vibration tests as well as centric and eccentric work.n
Abstract