Twenty years monitoring of a high strength concrete cantilever bridge

In 1997 the Second Stichtse Bridge, a high strength concrete box girder bridge was built in the Netherlands using the balanced cantilever method. At that time, the long-term behaviour of this material (with a cube compressive strength of 75 MPa) was not known. Therefore, it was proposed to monitor the material behaviour and the deflections of the bridge for ten years, and a few properties have been monitored for twenty years. To evaluate the concrete material properties over time, concrete cubes were cast with the segments, and stored inside the bridge at the section locations. These samples have been tested periodically. Also shrinkage measurements were carried out on a concrete sample stored inside the bridge. The deflections of the bridge superstructure have been measured periodically along both edges of the bridge. Based on the available data, it is found that the concrete compressive and splitting tensile strength, as well as the shrinkage deformations, remain constant. The deflections are stabilizing as well.