Innovative strengthening of road bridges with iron-based shape memory alloys (Fe-SMA)

Abstract

Bridge over Chodovsky stream is a composite structure made of fillerbeam deck, erected in 2017 in Karlovy Vary (Czech Republic). Urgent need of repair works on the bridge arose due to excessive effects of creep and subsequent deflection compromising the driving comfort. A bolted retrofit (BR) system was developed to apply pre-strained Fe-SMA prestressing bars. The shape memory effect (SME) of Fe-SMA was used for prestressing of the retrofit bars to increase the flexural resistance of the filler beam deck as well as to reduce the bridge static deflection. After the Fe-SMA strengthening of Petrov bridge in May of 2019 (bridge was demolished in July of 2019), this is to the best of author’s knowledge second application of this kind of strengthening and first permanent application of Fe-SMA to the bridge structure. Because of its novelty, the possibility for monitoring and evaluation of Fe-SMA-strengthening reliability on real bridge structure subjected to daily traffic is of great value.Wireless monitoring system was installed prior to the strengthening application. For the short-term measurements, the bridge was loaded with four 32-ton trucks before and after strengthening. The results of short- and long-term measurements show the effectivity and reliability of the Fe-SMA strengthening for current structures. The relaxation of Fe-SMA is evaluated and the results are compared with preliminary laboratory testing of the same BR strengthening system.