TY - GEN

T1 - A strengthening theory to prevent fatigue crack initiation in old metallic bridges

AU - Ghafoori, E.

AU - Motavalli, M.

AU - Nussbaumer, A.

AU - Zhao, X. L.

AU - Herwig, A.

AU - Fontana, M.

AU - Prinz, G. S.

N1 - Funding Information: This research was mainly funded by the Swiss Commission of Technology and Innovation (CTI) (No. 12993.1 PFIW-IW). The authors would also like to thank Mr. Tobias Humbel and the technicians of the Structural Engineering Research Laboratory of Empa for their excellent cooperation in performing the experiments. The authors gratefully acknowledge the support from the Fpsilon Composite Company, France, and the S&P Clever Reinforcement Company AG, Switzerland, for providing the materials for this study. Support from the Australian Research Council Linkage Grant (No. LP 140100543) is also appreciated.

PY - 2016

Y1 - 2016

N2 - Analytical solutions were developed to determine the fatigue resistance of metallic members retrofitted by bonded carbon fiber-reinforced polymer (CFRP) laminates. Different fatigue failure criteria based on the constant life diagram (CLD) approach were introduced to predict the strengthening properties that would prevent fatigue cracks in metallic members. The use of normal modulus (NM), high modulus (IIM) and ultra-high modulus (UHM) CFRP laminates with different pre-stress levels was considered in the modeling. To validate the model, a series of fatigue experiments were performed on four steel beams strengthened with bonded NM, HM and UHM CFRP laminates. The results have shown that there are two main mechanisms that can transition the detail from a risky finite-life regime to a safe infinite-life regime. In particular, UHM laminates have been shown to be effective to prevent fatigue crack initiation in steel members. In this paper bonded CFRP laminates were used for strengthening, however, the method can be applied for other retrofit elements such as un-bonded laminates, bolted steel plates and pre-stressed steel tendons.

AB - Analytical solutions were developed to determine the fatigue resistance of metallic members retrofitted by bonded carbon fiber-reinforced polymer (CFRP) laminates. Different fatigue failure criteria based on the constant life diagram (CLD) approach were introduced to predict the strengthening properties that would prevent fatigue cracks in metallic members. The use of normal modulus (NM), high modulus (IIM) and ultra-high modulus (UHM) CFRP laminates with different pre-stress levels was considered in the modeling. To validate the model, a series of fatigue experiments were performed on four steel beams strengthened with bonded NM, HM and UHM CFRP laminates. The results have shown that there are two main mechanisms that can transition the detail from a risky finite-life regime to a safe infinite-life regime. In particular, UHM laminates have been shown to be effective to prevent fatigue crack initiation in steel members. In this paper bonded CFRP laminates were used for strengthening, however, the method can be applied for other retrofit elements such as un-bonded laminates, bolted steel plates and pre-stressed steel tendons.

UR - http://www.scopus.com/inward/record.url?scp=85000879032&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:85000879032

SN - 9781138028517

T3 - Maintenance, Monitoring, Safety, Risk and Resilience of Bridges and Bridge Networks - Proceedings of the 8th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2016

SP - 862

EP - 869

BT - Maintenance, Monitoring, Safety, Risk and Resilience of Bridges and Bridge Networks - Proceedings of the 8th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2016

A2 - Beck, Andre T.

A2 - Frangopol, Dan M.

A2 - Bittencourt, Tulio Nogueira

T2 - 8th International Conference on Bridge Maintenance, Safety and Management, IABMAS 2016

Y2 - 26 June 2016 through 30 June 2016

ER -