The Experts below are selected from a list of 2385 Experts worldwide ranked by ideXlab platform

Jialai Wang - One of the best experts on this subject based on the ideXlab platform.

  • subCritical Debonding of frp to concrete bonded interface under synergistic effect of load moisture and temperature
    Mechanics of Materials, 2016
    Co-Authors: Shahrooz Amidi, Jialai Wang
    Abstract:

    Abstract External bonding of Fiber Reinforced Polymers (FRP) has played an important role in rehabilitation and retrofitting of aged reinforced concrete structures in the last two decades. However, the long-term durability of the FRP-to-concrete bonded interface is still an unresolved issue, which hampers the widespread use of these techniques. An environment-assisted subCritical Debonding testing (EASD) program using a static wedge specimen is carried out in this study to evaluate the long-term durability of the FRP-to-concrete interface subjected to the synergistic effect of mechanical load, moisture, and temperature. Unlike commonly used Critical Debonding-based testing methods, EASD allows for interaction among mechanical load and environmental conditions (moisture and temperature), providing more insight into the degradation mechanisms of the interface between the concrete and the strengthening material. A commercially available coupling agent, γ-GPS was used to treat the concrete surface to improve the durability of the interface. This is because the coupling agent can introduce covalent bonds between the epoxy and concrete, which is much stronger than the hydrogen bonds formed between the epoxy and the concrete without coupling agents. Testing results shows that the moisture and temperature have significant effects on the subCritical Debonding of the interface. A failure mode change from cohesive failure in the concrete in the air to the adhesive failure along the epoxy-concrete interface under aqueous condition was observed in the subCritical Debonding of the FRP-to-concrete interface. EASD testing data confirms that the durability of the epoxy-concrete interface can be significantly enhanced by coupling agent treatment.

Marino Quaresimin - One of the best experts on this subject based on the ideXlab platform.

  • modelling fibre matrix Debonding under biaxial loading
    Composites Part A-applied Science and Manufacturing, 2014
    Co-Authors: Paolo Carraro, Marino Quaresimin
    Abstract:

    Abstract In the present work, a model for fibre–matrix Debonding initiation under the biaxial loading condition (plane tension combined with out of plane shear) is proposed. The model is developed within the frame of Finite Fracture Mechanics and it is capable of predicting the Critical stress value for the onset of Debonding and the length of the initial defect. A parametric analysis is carried out to understand the influence of the main geometric and interface parameters on the Critical Debonding stress, which is found to be strongly dependent on the fibre radius. Satisfactory agreement with experimental data from the literature suggests that this approach, suitably adapted, might also be applied in the case of a unidirectional composite lamina, representing a very useful tool for modelling composite material behaviour under multiaxial loading conditions.

  • The Effect of Surface Stresses on the Critical Debonding Stress Around Nanoparticles
    International Journal of Fracture, 2011
    Co-Authors: Marco Salviato, Michele Zappalorto, Marino Quaresimin
    Abstract:

    With the aid of an energy analysis and the surface elasticity theory, this work provides a closed form solution for the Critical Debonding stress of a rigid nanoparticle embedded in an elastic matrix subjected to a remote hydrostatic stress. It is proved that the Debonding stress depends on the particle radius, the matrix elastic properties and the fracture energy per unit surface. The solution allows quantifying the effects of surface elastic constants, also showing that the smaller the particle size the more significant those effects are.

Riadh Almahaidi - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of premature failure of frp bonded to concrete using mechanical substrate strengthening and frp spike anchors
    Composites Part B-engineering, 2016
    Co-Authors: Robin Kalfat, Riadh Almahaidi
    Abstract:

    Abstract Fiber reinforced polymers (FRPs) are being increasingly used to strengthen and repair existing reinforced concrete (RC) structures and possess many advantages with respect to other strengthening methods, such as externally bonded (EB) steel plates. It is presently understood that the strength of the concrete substrate is a key factor affecting the Debonding failure mode and the overall bond strength of FRP materials. Although researchers have investigated the application of FRP anchorage systems to delay the Critical Debonding failure mode, increasing the strength of the concrete substrate to achieve the same goals has been little investigated to date. The present study investigates substrate strengthening techniques in an experimental program where 30–40 mm wide × 20 mm deep concrete chases within the concrete cover zone are introduced in both transverse and longitudinal orientations in order to strengthen the substrate to which the FRP is bonded. In addition, the concept of using two FRP spike anchor dowels with one end drilled into the concrete and the other end bonded to the FRP laminate is evaluated. All of the enhancement techniques tested demonstrated significant enhancements in bond strength.

Shahrooz Amidi - One of the best experts on this subject based on the ideXlab platform.

  • subCritical Debonding of frp to concrete bonded interface under synergistic effect of load moisture and temperature
    Mechanics of Materials, 2016
    Co-Authors: Shahrooz Amidi, Jialai Wang
    Abstract:

    Abstract External bonding of Fiber Reinforced Polymers (FRP) has played an important role in rehabilitation and retrofitting of aged reinforced concrete structures in the last two decades. However, the long-term durability of the FRP-to-concrete bonded interface is still an unresolved issue, which hampers the widespread use of these techniques. An environment-assisted subCritical Debonding testing (EASD) program using a static wedge specimen is carried out in this study to evaluate the long-term durability of the FRP-to-concrete interface subjected to the synergistic effect of mechanical load, moisture, and temperature. Unlike commonly used Critical Debonding-based testing methods, EASD allows for interaction among mechanical load and environmental conditions (moisture and temperature), providing more insight into the degradation mechanisms of the interface between the concrete and the strengthening material. A commercially available coupling agent, γ-GPS was used to treat the concrete surface to improve the durability of the interface. This is because the coupling agent can introduce covalent bonds between the epoxy and concrete, which is much stronger than the hydrogen bonds formed between the epoxy and the concrete without coupling agents. Testing results shows that the moisture and temperature have significant effects on the subCritical Debonding of the interface. A failure mode change from cohesive failure in the concrete in the air to the adhesive failure along the epoxy-concrete interface under aqueous condition was observed in the subCritical Debonding of the FRP-to-concrete interface. EASD testing data confirms that the durability of the epoxy-concrete interface can be significantly enhanced by coupling agent treatment.

Robin Kalfat - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of premature failure of frp bonded to concrete using mechanical substrate strengthening and frp spike anchors
    Composites Part B-engineering, 2016
    Co-Authors: Robin Kalfat, Riadh Almahaidi
    Abstract:

    Abstract Fiber reinforced polymers (FRPs) are being increasingly used to strengthen and repair existing reinforced concrete (RC) structures and possess many advantages with respect to other strengthening methods, such as externally bonded (EB) steel plates. It is presently understood that the strength of the concrete substrate is a key factor affecting the Debonding failure mode and the overall bond strength of FRP materials. Although researchers have investigated the application of FRP anchorage systems to delay the Critical Debonding failure mode, increasing the strength of the concrete substrate to achieve the same goals has been little investigated to date. The present study investigates substrate strengthening techniques in an experimental program where 30–40 mm wide × 20 mm deep concrete chases within the concrete cover zone are introduced in both transverse and longitudinal orientations in order to strengthen the substrate to which the FRP is bonded. In addition, the concept of using two FRP spike anchor dowels with one end drilled into the concrete and the other end bonded to the FRP laminate is evaluated. All of the enhancement techniques tested demonstrated significant enhancements in bond strength.