Experimental investigation on the CFRP strengthening efficiency of steel plates with inclined cracks under fatigue loading. (1st October 2018)

• Record Type: Journal Article
• Authors: Aljabar, N.J.; Zhao, X.L.; Al-Mahaidi, R.; Ghafoori, E.; Motavalli, M.; Koay, Y.C.
• Is Part Of: Engineering structures. Volume 172(2018)
• Page Start: 877
• Page End: 890
• Publication Date: 2018-10-01
• Subjects: CFRP properties -- CFRP strengthening -- Mixed-mode (I + II) -- Fatigue test -- Inclined crack -- Initial crack length -- Damage degree -- Steel plate -- Fatigue life; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2018.06.074
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: Fatigue tests were conducted on CFRP strengthened steel plates with inclined cracks. CFRP modulus was less important when strengthening steel plates with inclined cracks. Fibre orientation was important when strengthening steel plates with inclined cracks. Mixed-mode modification factor was derived to predict fatigue life involving inclined cracks. Abstract: Employing advanced material such as carbon‐fibre‐reinforced‐polymer (CFRP) in tension fatigue strengthening of aged roads and railway bridges have shown a great capability of arresting or delaying crack initiation and/or propagation in steel structures. However, it is not clear whether the fatigue behaviour and the CFRP strengthening efficiency is the same when the cracked-steel elements exhibit a state of complex loading. The aim of this paper is to investigate the fatigue behaviour of the CFRP strengthening of steel plates with central initial inclined cracks with a focus on the effect of the CFRP properties. The initial slit-like cracks were oriented to introduce a state of combined action of tension (mode-I) and shear (mode II) stresses at the crack tips. The key parameters in this study are the mixed‐mode (shear to tension stresses) ratio, the crack-starter length ratio (initial crack length to the plate width), patching configurations, and mechanical properties of the composite material. All the test specimens were artificially notched with central cracks of different damage levels. This study covered the fatigue performance of steel plates strengthened with two configurations of composite materials of different tensile stiffness (high modulus CFRP sheets, and normal modulus CFRP plates). Furthermore, the efficiency of strengthening systems of different fibre orientation relative to the initial crack angle was investigated. The outcomes of this study are extending the current knowledge of the CFRP strengthening to its applications on metal plates contain defects subjected to mixed-mode fatigue loading.