Zuhair Al-Jaberi; John J. Myers; K. Chandrashekhara
Abstract
The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability ...
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The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability by considering exposure to harsh environmental conditions and testing the specimens after exposure, rather than testing bond performance during exposure. The influence of directly applying temperature on bond behavior represents an open topic that needs to be investigated in more detail. This study is one of the first studies to investigate the bond behavior when the composite is subjected to tension force simultaneously with applying temperature. The temperatures considered in this study were at freezing, ambient, and high temperature, which are more representative of structural elements under field conditions. A total of 16 specimens were strengthened and tested under single-lap direct shear. The key parameters investigated include (a) the type of fiber [laminate carbon vs. wet layup glass] (b) the level of temperature applied on specimen, including ambient condition 21°C (70 °F), freeze condition -18 °C (0 °F) and hot weather 49 °C (120 °F), and (c) the exposure regime (direct exposure during loading process vs. loading after exposure). Most of the specimens were subjected to tension force simultaneously with applying temperature, and the other specimens were later tested after exposure to the heating and cooling cycles. These cycles are proposed to simulate 20 years of the typical in-situ weather conditions in the Central United States. The results showed that overall the EB strengthening systems exhibited good performance when subjected to cycles of heating and cooling prior to testing. High reduction of FRP-epoxy bond properties was up to 59% when exposed to high service temperatures. Different modes of failure were observed such as debonding at fiber-matrix interface and debonding due to shearing in laminate.
Hayder H. Alghazali; Zuhair K. Al-Jaberi; Zena R. Aljazaeri; John J. Myers
Abstract
To experimentally examine the ability of the steel reinforced polymer (SRP) in restoring the moment capacity compromised by damage in the main steel reinforcement, six full-scale reinforced concrete (RC) beams were designed to simulate impact damage from over height vehicle collision. The simulation ...
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To experimentally examine the ability of the steel reinforced polymer (SRP) in restoring the moment capacity compromised by damage in the main steel reinforcement, six full-scale reinforced concrete (RC) beams were designed to simulate impact damage from over height vehicle collision. The simulation was represented by concrete beams reinforced with discontinuous reinforcement (splice in maximum moment region) and tested until failure due to splice. The damaged concrete was repaired, and the SRP system (longitudinal soffit laminates and transverse U-wraps) was applied to restore the original moment capacity. All beams were 10 ft (3.0 m) in length, 18 in. (457 mm) in depth, and 12 in. (305 mm) in width. Different repairing configurations were investigated. The studied variables were the provided laminate area and the amount and distribution of U-wraps. The ultimate load capacity, deflection, and mode of failure were recorded during testing. The test results were compared to beam results with continuous reinforcement. It was concluded that the repairing beams with the SRP system can restore the damaged beams to a capacity similar to that of a non-damaged reinforced concrete (RC) beam with continuous reinforcement.
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