Time-dependent behaviour of widened reinforced concrete under-bridge

The paper reports on data acquired during 700 days of monitoring a widened reinforced concrete under-bridge. The deck was monitored before, during and after widening and both portions of the deck, existing and new, were instrumented. Concrete strains were monitored by means of embedment and surface Vibrating Wire strain Gauges (VWG). Predicted creep, shrinkage, thermal and settlement strains were evaluated by means of a finite element analysis. The creep and shrinkage factors used were those from the simplified form of the B3 model [1]. Good agreement between calculated and measured longterm strains was observed at almost all gauge positions. From the analysis carried out, it was found that the stresses from the time dependent phenomena of creep, shrinkage and temperature, combined with those from the settlement of abutments, were greater than the magnitude of stresses obtained from the design live load.