Long-term material and structural behavior of high-strength concrete cantilever bridge: Results of 20 years monitoring

In 1997, the Second Stichtse Bridge was built in the Netherlands using the balanced cantilever method. The use of high-strength concrete was proposed. At that time, the long-term behaviour of this material was not known, and no code provisions were applicable. Therefore, it was proposed to monitor the material behaviour and the deflections of the bridge. To evaluate the development of the concrete compressive strength and the concrete splitting tensile strength over time, concrete cubes were cast at the same time as each of the cantilever segments, and stored inside the bridge. These samples have been tested at different points in time to study the development of the strength as a function of the elapsed time. Creep and shrinkage measurements were carried out on samples stored inside the bridge as well as in the laboratory. Temperature and moisture were monitored as well. The deflections of the bridge superstructure have been measured periodically. These measurements can be compared to predictions from finite element models. Based on the available data, it is found that the concrete compressive and splitting tensile strength remain constant. The deflections are small, and the advanced finite element models resulted in good predictions.