Performance of Postinstalled GFRP Bars in Structural Connections
Publication: Journal of Composites for Construction
Volume 26, Issue 2
Abstract
This research experimentally investigated the applicability of glass fiber–reinforced polymer (GFRP) bars as postinstalled reinforcement in structural connections. The test specimens included two identical vertical elements, which were anchored into a reinforced concrete base using postinstalled GFRP bars replicating a beam–column or beam–wall connection. The variables investigated included the GFRP bar embedment depth (150 and 290 mm), concrete compressive strength (20.7 and 41.4 MPa), and postinstalled GFRP bar size (Nos. 13, 19, or 25). A total of 16 specimens were subjected to combined tension and shear loading. Concrete breakout in tension was the failure mode in all specimens. The concrete breakout strengths improved by increasing the embedment depths and concrete strengths and worsened as the GFRP bar diameter increased while keeping the embedment depth and concrete strength constant. The authors recommend using anchor provisions from current standards to estimate the concrete breakout strength of post-installed GFRP bars (Nos. 13–19) tested with the parameters described herein.
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Acknowledgments
The authors are grateful to Harris Rebar, Hilti Inc., Hughes Brother Inc., Pultrall Canada, and Marshall Composite Technologies for providing the materials used in this research. The conclusions expressed in this paper are those of the authors and do not necessarily reflect the views of the material suppliers.
Notation
The following symbols are used in this paper:
- Afbar
- area of one FRP bar, mm2;
- ANc
- projected concrete failure area of a single bar or group of bars, for calculation of strength in tension, mm2;
- ANco
- projected concrete failure area of a single bar or group of bars, for calculation of strength in tension if not limited by edge distance or spacing, mm2;
- AVc
- projected concrete failure area of a single anchor or group of anchors, for calculation of strength in shear, mm2;
- AVco
- projected concrete failure area of a single anchor, for calculation of strength in shear, if not limited by corner influences, spacing, or member thickness, mm2;
- ca1
- distance from the center of an anchor shaft to the edge of concrete in one direction, in. If shear is applied to the anchor, ca1 is taken in the direction of the applied shear. If tension is applied to the anchor, ca1 is the minimum edge distance, mm;
- db
- diameter of reinforcing bar, mm;
- compressive strength of concrete, MPa;
- ff
- stress on GFRP bars, MPa;
- hef
- effective embedment depth of bar, mm;
- le
- embedment depth of reinforcing bar, mm;
- u
- average bond stress, MPa;
- ϕ
- strength reduction factor;
- ψc,N
- factor used to modify the tensile strength of bars based on the absence or presence of cracks in concrete;
- ψc,V
- factor used to modify the tensile strength of bars based on the absence or presence of cracks in concrete and the presence or absence of supplementary reinforcement;
- ψcp,N
- factor used to modify tensile strength of postinstalled bars intended for use in uncracked concrete without supplementary reinforcement to account for splitting tensile stresses due to installation;
- ψec,N
- factor used to modify the tensile strength of bars based on the eccentricity of the applied loads;
- ψec,V
- factor used to modify the shear strength of bars based on the eccentricity of the applied loads;
- ψed,N
- factor used to modify tensile strength of bars based on proximity to edges of concrete members;
- ψed,V
- factor used to modify shear strength of bars based on proximity to edges of concrete members;
- ψh,V
- breakout thickness factor used to modify the shear strength of anchors; and
- λa
- modification factor to reflect the reduced mechanical properties of lightweight concrete in certain concrete anchorage applications.
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Received: Nov 17, 2020
Accepted: Nov 13, 2021
Published online: Jan 6, 2022
Published in print: Apr 1, 2022
Discussion open until: Jun 6, 2022
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