Modeling Bond Between Corrosion-Cracked Concrete and Composite Sheets
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RESEARCH PAPER
Modeling Bond Between Corrosion-Cracked Concrete and Composite Sheets Rami H. Haddad1
•
Abeer Al Dalou1
Received: 17 March 2020 / Revised: 15 June 2020 / Accepted: 27 June 2020 Ó Iran University of Science and Technology 2020
Abstract A new empirical model for the prediction of bond strength between corrosion-cracked concrete and FRP sheets is proposed in this work. The model considers the impact of concrete-cracking level as well as the geometric characteristics of FRP sheets. Experimental data (from tests on reinforced concrete blocks underwent varying corrosion levels before attached to carbon FRP (CFRP) sheets at variable bond lengths and widths) is employed in the empirical modeling. Corrosion-induced cracks at widths of about 0.2–0.9 mm lead to reductions in bond strength and slippage at failure at ranges of 25–44% and 18–68%, respectively. The developed statistical model captures the correct trend for bond stress–slip relationship and precisely predicts bond characteristics between corroding concrete and CFRP sheets in terms of key parameters. The degradation parameters (incorporated in this model) confirmed those provided by the ACI committee 440 at ranges of 0.66–0.86 for bond strength and 0.63–0.89 for slip at ultimate bond stress. The prediction accuracy of the present model of published data shows the highest when compared with that of well-known published models. Keywords Concrete Corrosion Cracks Bond Composite materials Modeling
1 Introduction Concrete elements are susceptible to active steel corrosion especially in marine structures or whenever deicing agents are frequently used [1]. Of course, flexural components in such structures corrode the most, because their horizontal alignment allows the easy intrusion of chloride, triggering reinforcing steel corrosion in a short period of time. The corrosion damage shows as a reduction in the effective cross-sectional area of reinforcement, undesirable changes in surface and mechanical characteristics of reinforcing steel, and cracking or spalling of concrete. Consequently, structural and durability performances of respective reinforced concrete elements are substantially reduced while deformability is increased [2–6]. Hence, urgent repair measures to recover the structural capacity and maintain & Rami H. Haddad [email protected] Abeer Al Dalou [email protected] 1
the durability become necessary to avert catastrophic failures. Several repair techniques have been used during the past 30 years or so; the most common of which is the externally attached fiber-reinforced polymer (FRP) composites in sheet or strip form [7–10]. Field observations revealed that cracks’ intensity, distribution, and average width size are major factors that limit the advantage of using externally attached carbon FRP (CFRP) composites for repair or strengthening objectives [11–16]. Thermal cracks (generated by the heating of concrete to temperatures up to 600 °C) were reported to undermine bond
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