Long Term Measuring of Expansions and Contractions of Pre-Stressed Concrete Bridge Structure

The presented paper considers approx. 5 years measurement on concrete railway bridge. The span is 39.875 + 34.877 + 37.000 + 9 x 31.500 m. The total length of the bridge is 443 m. Structure possesses typical three-box cross section. Monitoring was focused on temperature of concrete, temperature of atmosphere in the shade and mainly on measurement of movements of several bearings. Because the monitoring period of bridge structure was approx. 5 year, the probability p = 0.2 (5 years returning period) was chosen in order to compare measured data with standard values according to EN 1991-1-5. Of course, the standard value was assumed without any safety factor for this purpose. The maximal difference of measured and standard values was only 25 mm. This was achieved on the pillar where measured value of displacement range was 135 mm, standard value 160 mm and the dilatation length was 332 m. On the other hand, the minimal difference was only 3 mm on the pillar where measured value was 33 mm, standard value 36 mm and the dilatation length was 75 m. If the approx. 5 years measurement is compared with theoretical value of 5 years return period, the standard procedure cannot be classified as very conservative. It was shown that the long-time measurement is very important for the further development and improvement of the Eurocodes as well as statistical approach, i.e., returning time which shall be taken into account.