smart_tendon

Road bridges are frequently constructed using prestressed concrete. In this method, the concrete is subjected to compressive forces by means of tensioned steel tendons, which allows for bridge components with relatively small cross-sectional dimensions that are less prone to cracking. In order to ensure that bridges can be used for as long as possible, maintained efficiently and, as a result, conserve resources, their condition is monitored. This is carried out through regular visual inspections and, increasingly, through the use of measurement technology.

The resulting database could be significantly expanded through the long-term measurement of deformations within the bridge structure. For this reason, the research project is dedicated to the integration of spatially resolved strain sensors into tendons for new concrete bridges. The resulting intelligent tendons, known as ‘smart tendons’, will enable data on the condition of concrete bridges to be recorded throughout their entire service life.

Preference is to be given to a fibre-optic measurement principle, which enables spatially resolved strain measurement along the tendons. This allows any structural damage that may occur to be detected and localised at an early stage, enabling the efficient planning of maintenance measures and thus extending the service life of the bridges.

Various technical approaches are being pursued for the robust and permanent integration of strain sensors into the tendons. Initially, laboratory tests are being carried out on individual tendons equipped with fibre-optic strain sensors, i.e. on the so-called ‘smart tendons’. Subsequently, the ‘smart tendons’ will be tested in-situ, first in large-scale laboratory tests on prestressed concrete beams and subsequently in a real bridge structure. Bridge monitoring concepts incorporating the strain measurement data obtained are also being developed.