TY - JOUR

T1 - Development of Mechanical Strengthening System for Bridge Connections Using Prestressed CFRP Rods

AU - Heydarinouri, Hossein

AU - Motavalli, Masoud

AU - Nussbaumer, Alain

AU - Ghafoori, Elyas

N1 - Funding Information: This work has been funded primarily by the Innosuisse Swiss Innovation Agency (Grant ID 19240.1 PFIW-IW). The authors would also like to acknowledge the financial and technical support from S&P Clever Reinforcement Company AG, Switzerland; the Swiss Federal Railways (SBB) AG, Bern; and dsp Ingenieure + Planer AG Engineering Office, Uster, Switzerland, for this project. They also thank the technicians from the Structural Engineering Research Laboratory of Empa for their outstanding collaborations during the experiments. Finally, the scientific and technical support from Dr. Ardalan Hosseini, postdoctoral scholar at the University of California, Davis, in different stages of the design of the strengthening system is highly appreciated. Publisher Copyright: © 2020 American Society of Civil Engineers.

PY - 2021/3/1

Y1 - 2021/3/1

N2 - Stringer-to-floor beam web-to-web double-angle connections are among the most fatigue-prone elements in old riveted bridges. These connections are often designed to carry only shear loads. However, in these elements, fatigue damage occurs because of the out-of-plane deformation of the connections, which is ignored in the original design. In this study, a new retrofitting system is developed to reduce the out-of-plane deformation of the connections using prestressed carbon fiber-reinforced polymer (CFRP) rods. The proposed system consists of a mechanical wedge-barrel anchor to hold the prestressed CFRP rod and a clamping system to attach to the parent structure and to transmit forces via friction. A series of finite-element (FE) simulations was conducted to optimize the size and performance of the retrofit system. Laboratory static pull-off tests were conducted and different failure modes were studied and discussed. A novel test setup (with four supports) was designed for testing the steel connections. The effect of the geometrical imperfections during the installation of the connection was carefully investigated using the FE models and was verified through laboratory the tests. Laboratory fatigue tests were conducted on steel connections with the same dimensions as those in a railway bridge. The designed retrofit system was found to be capable of reducing the stresses at the angle connections by more than 40%. The results of the fatigue tests demonstrated that the designed system could survive more than 11 million load cycles without any fatigue damage or any indication of a loss in the CFRP prestressing level.

AB - Stringer-to-floor beam web-to-web double-angle connections are among the most fatigue-prone elements in old riveted bridges. These connections are often designed to carry only shear loads. However, in these elements, fatigue damage occurs because of the out-of-plane deformation of the connections, which is ignored in the original design. In this study, a new retrofitting system is developed to reduce the out-of-plane deformation of the connections using prestressed carbon fiber-reinforced polymer (CFRP) rods. The proposed system consists of a mechanical wedge-barrel anchor to hold the prestressed CFRP rod and a clamping system to attach to the parent structure and to transmit forces via friction. A series of finite-element (FE) simulations was conducted to optimize the size and performance of the retrofit system. Laboratory static pull-off tests were conducted and different failure modes were studied and discussed. A novel test setup (with four supports) was designed for testing the steel connections. The effect of the geometrical imperfections during the installation of the connection was carefully investigated using the FE models and was verified through laboratory the tests. Laboratory fatigue tests were conducted on steel connections with the same dimensions as those in a railway bridge. The designed retrofit system was found to be capable of reducing the stresses at the angle connections by more than 40%. The results of the fatigue tests demonstrated that the designed system could survive more than 11 million load cycles without any fatigue damage or any indication of a loss in the CFRP prestressing level.

KW - Bridge connections

KW - Carbon fiber-reinforced polymer (CFRP)

KW - Finite element (FE)

KW - Posttensioned CFRP tendons

KW - Strengthening

KW - Wedge-barrel anchor

UR - http://www.scopus.com/inward/record.url?scp=85098174205&partnerID=8YFLogxK

U2 - 10.1061/(ASCE)ST.1943-541X.0002923

DO - 10.1061/(ASCE)ST.1943-541X.0002923

M3 - Article

AN - SCOPUS:85098174205

VL - 147

JO - Journal of Structural Engineering (United States)

JF - Journal of Structural Engineering (United States)

SN - 0733-9445

IS - 3

M1 - 4020351

ER -