Experimental bond behaviour of GFRP and masonry bricks under impulsive loading

Fibre Reinforced Polymers have become a popular material for strengthening of masonry structures. The performance of this technique is strongly dependent on the bond between the FRP and the substrate. Understanding the strain rate effect on these materials and strengthening techniques is important for proper design and proper modelling of these systems under impacts or blast loads. This work aims to study the behaviour of the bond between GFRP and brick at different strain rates. A Drop Weight Impact Machine specially developed for pull-off tests (single shear tests) is used with different masses and different heights introducing different deformation rates. The strain rate effect on the failure mode, shear capacity and effective bond length is determined from the experimental results. Empirical relations of dynamic increase factors (DIF) for these materials and techniques are also presented.This work was performed under Project CH-SECURE (PTDC/EMC/120118/2010) funded by the Portuguese Foundation of Science and Technology – FCT. The authors acknowledge the support. The first author also acknowledges the support from his PhD FCT grant with the reference SFRH/BD/45436/2008

Local bond-slip relationship for FRP reinforcement in concrete

The objective of this paper is to define a rigorous numerical method to calibrate parameters of a given local bond-slip relationship using experimental results of pullout tests, taking into account the distribution of the slip and bond shear stress throughout the bar. The proposed method involves finding parameters of a given bond-slip relationship, such that results of pullout tests can be predicted in terms of applied pullout force and consequent slip at the loaded end and slip at the free end. The method is applied to some experimental data, and the results are discussed. For the application of the proposed method, two analytical expressions of the bond-slip relationship are selected, even though it could be applied to any analytical expression. An example of determination of anchorage length starting from the knowledge of the local bond-slip relationship is given

Mechanical behavior of fiber-reinforced polymer-wrapped concrete columns-complicating effects

The present study focuses on the mechanical response of concrete columns confined with fiber-reinforced polymer composites (FRP). Practical columns often deviate from axisymmetric conditions due to noncircular cross section, geometric imperfections, and loading eccentricities. This paper discusses these complicating effects on the mechanical behavior of columns confined with FRP. Experiments have been carried out to examine the effects of geometric and loading imperfections on columns of various shapes. A model originally developed for axisymmetric situations has been extended to include the complicating effects. An analytical study for the corner radius that avoids concentration of stress is carried out. The theoretical models have been verified with the present and published experimental results

AASHTO Design Specifications for GFRP-RC Bridges: 2nd Edition

The development of a comprehensive bridge design national standard is paramount to allow for a wider and safe deployment of Glass Fiber Reinforced Polymer (GFRP) Reinforced Concrete (RC) in the transportation infrastructure. To respond to this demand, a task force of researchers, practitioners, and transportation officials lead by the University of Miami (UM), the University of South Carolina (USC), and the Florida Department of Transportation (FDOT), has developed a draft of the second edition of the Bridge Design Guide Specifications for GFRP-RC (BDGS-GFRP), now under consideration by the American Association of State Highway and Transportation Officials (AASHTO) committee T6. This paper deals with the salient contents of the document, with specific emphasis on the design of flexural members. Compared to the first edition, changes were proposed to reflect the state-of-the-art from archival literature and harmonize the design philosophy with that of other authoritative national and international standards