TY - JOUR

T1 - Fatigue tests on UHM-CFRP strengthened steel plates with central inclined cracks under different damage levels

AU - Aljabar, N. J.

AU - Zhao, X. L.

AU - Al-Mahaidi, R.

AU - Ghafoori, E.

AU - Motavalli, M.

AU - Koay, Y. C.

N1 - Funding Information: The authors gratefully acknowledge the financial support provided by the Australian Research Council through an ARC Linkage Grant ( LP140100543 ) with VicRoads and S&P Clever Reinforcement Company AG as industry partners. The first author wishes to thank the Higher Committee for Education Development in Iraq for sponsoring his research at Monash University. Thanks are given to all technical staff in the civil engineering laboratory at Monash University, especially Mr. Long Goh and Mr. Saravanan Mani, for their technical support.

PY - 2017/1/15

Y1 - 2017/1/15

N2 - Ageing structures and metallic bridges, in particular, are vulnerable to fatigue failure due to having sensitive fatigue details. The literature on upgrading these structures highlights the efficiency of tensile (mode I) fatigue strengthening using carbon fibre reinforced polymer (CFRP) composites. However, cracks or defects are often oriented to the loading angle, which develops mixed-mode (I + II) conditions that govern crack propagation. Therefore, the efficacy of mode-I fatigue strengthening needs to be evaluated under such conditions and at different stages of the fatigue service life. This paper extends the current understanding of fatigue strengthening with CFRP from mode I loading to the case of mixed-mode (I + II) with different initial damage level. CFRP-strengthened steel plates were produced with six loading angles between 90° and 10° and two damage levels. Test results revealed that the mixed-mode crack propagation curves of steel plates strengthened at different stages of their fatigue life were approximated by the same crack growth curve in pure tensile mode by utilizing the shifting concept. Mixed mode modification factor was derived from test results of 36 specimens to predict the fatigue life of CFRP-strengthened steel plates initially inclined cracked with various degrees of damage.

AB - Ageing structures and metallic bridges, in particular, are vulnerable to fatigue failure due to having sensitive fatigue details. The literature on upgrading these structures highlights the efficiency of tensile (mode I) fatigue strengthening using carbon fibre reinforced polymer (CFRP) composites. However, cracks or defects are often oriented to the loading angle, which develops mixed-mode (I + II) conditions that govern crack propagation. Therefore, the efficacy of mode-I fatigue strengthening needs to be evaluated under such conditions and at different stages of the fatigue service life. This paper extends the current understanding of fatigue strengthening with CFRP from mode I loading to the case of mixed-mode (I + II) with different initial damage level. CFRP-strengthened steel plates were produced with six loading angles between 90° and 10° and two damage levels. Test results revealed that the mixed-mode crack propagation curves of steel plates strengthened at different stages of their fatigue life were approximated by the same crack growth curve in pure tensile mode by utilizing the shifting concept. Mixed mode modification factor was derived from test results of 36 specimens to predict the fatigue life of CFRP-strengthened steel plates initially inclined cracked with various degrees of damage.

KW - CFRP strengthening

KW - Damage degree

KW - Fatigue

KW - Inclined cracks

KW - Initial crack length

KW - Steel plate

KW - Ultra-high modulus CFRP laminate

UR - http://www.scopus.com/inward/record.url?scp=85002900855&partnerID=8YFLogxK

U2 - 10.1016/j.compstruct.2016.10.122

DO - 10.1016/j.compstruct.2016.10.122

M3 - Article

AN - SCOPUS:85002900855

VL - 160

SP - 995

EP - 1006

JO - Composite structures

JF - Composite structures

SN - 0263-8223

ER -