TY - JOUR

T1 - Thermally-activated shape memory alloys for retrofitting bridge double-angle connections

AU - Izadi, Mohammadreza

AU - Motavalli, Masoud

AU - Ghafoori, Elyas

N1 - Funding Information: Zurich University of Applied Sciences (ZHAW), Winterthur, Switzerland, commissioned by State Secretariat for Education, Research and Innovation (SERI) for providing a mobility grant for bilateral research collaboration with South Asia and Iran 2017–2019 is recognized. The authors also thank the technicians of the Structural Engineering Research Laboratory of Empa, Switzerland, for their exceptional support in performing the experiments. Furthermore, the authors acknowledge support from Von Roll Deutschland GmbH and re-fer AG company, Switzerland, for providing the GFRP laminates and the Fe-SMA strips, respectively. Funding Information: Zurich University of Applied Sciences (ZHAW), Winterthur, Switzerland, commissioned by State Secretariat for Education, Research and Innovation (SERI) for providing a mobility grant for bilateral research collaboration with South Asia and Iran 2017?2019 is recognized. The authors also thank the technicians of the Structural Engineering Research Laboratory of Empa, Switzerland, for their exceptional support in performing the experiments. Furthermore, the authors acknowledge support from Von Roll Deutschland GmbH and re-fer AG company, Switzerland, for providing the GFRP laminates and the Fe-SMA strips, respectively. Publisher Copyright: © 2021 The Authors

PY - 2021/10/15

Y1 - 2021/10/15

N2 - Double-angle connections are prone to fatigue cracking in old steel bridges; however, owing to their complexity, there are not many retrofitting solutions for these details. This study proposes a retrofitting system for double-angle connections using iron-based shape memory alloys (Fe-SMAs). An innovative connection test setup equipped with an optical 3D digital image correlation (DIC) measurement system was developed. The retrofitting system included two end-anchorages set on either side of the connection. Fe-SMA strips were inserted inside the anchorages, and then were thermally activated (pre-stressed) to a temperature of 260 °C. Numerical finite element studies were performed to investigate the static behavior of the system. It was found that the activated/prestressed Fe-SMA strips not only apply a reverse positive moment on the connection (versus an undesirable negative fixity moment), but also “absorb” a portion of the negative moment, owing to the added axial stiffness. The proposed SMA-based system offers a versatile and cost-effective technique (with quick and easy installation) for bridge connections, and can significantly reduce the effects from undesirable sources of fatigue cracking.

AB - Double-angle connections are prone to fatigue cracking in old steel bridges; however, owing to their complexity, there are not many retrofitting solutions for these details. This study proposes a retrofitting system for double-angle connections using iron-based shape memory alloys (Fe-SMAs). An innovative connection test setup equipped with an optical 3D digital image correlation (DIC) measurement system was developed. The retrofitting system included two end-anchorages set on either side of the connection. Fe-SMA strips were inserted inside the anchorages, and then were thermally activated (pre-stressed) to a temperature of 260 °C. Numerical finite element studies were performed to investigate the static behavior of the system. It was found that the activated/prestressed Fe-SMA strips not only apply a reverse positive moment on the connection (versus an undesirable negative fixity moment), but also “absorb” a portion of the negative moment, owing to the added axial stiffness. The proposed SMA-based system offers a versatile and cost-effective technique (with quick and easy installation) for bridge connections, and can significantly reduce the effects from undesirable sources of fatigue cracking.

KW - Damage

KW - Fatigue crack

KW - Optical measurements

KW - Pre-stressing

KW - Rehabilitation

KW - Shape memory alloy (SMAs)

UR - http://www.scopus.com/inward/record.url?scp=85111206928&partnerID=8YFLogxK

U2 - 10.1016/j.engstruct.2021.112827

DO - 10.1016/j.engstruct.2021.112827

M3 - Article

AN - SCOPUS:85111206928

VL - 245

JO - Engineering structures

JF - Engineering structures

SN - 0141-0296

M1 - 112827

ER -