Mechanical Properties

Mechanical Properties of GFRP Fiberglass Rebar

Since the mechanical properties of GFRP fiberglass rebar differ from those of steel, design engineers should consider recommendations made in published design and construction guides prior to using GFRP fiberglass rebar in their structures.

If you require a brief overview of the suitability of using GFRP fiberglass rebar in your application please contact us at: or call us at 780-455-5105 or toll free at 1-877-455-5105

Several important differences between steel and GFRP fiberglass rebar should be considered prior to designing your concrete structures using fiberglass rebar:

  • Direct substitution of GFRP fiberglass rebar with steel rebar may not be possible in some cases
  • A lower modulus of elasticity and shear strength may impact the number of reinforcing bars required
  • GFRP fiberglass rebar has a limited maximum sustained shear stress.
  • Guaranteed design tensile strength of fiberglass rebar has to be de-rated in certain applications
  • Some types of GFRP fiberglass rebar are not suitable for certain pre-stressing or post-tensioning applications
  • Unlike steel reinforcement, the creep failure of FRP reinforcing bars may occur at tensile stress levels considerably lower than their static failure stress. Thus, the creep strength of a particular FRP bar type plays a role in determining its allowable service stress level. GFRP’S design codes reflect this characteristic of GFRP and should be followed. See the report on Creep in this section to understand this characteristic (or contact us).
  • GFRP rebar is two to three times stronger (in tensile) than grade 40 steel.  Reducing allowable stress levels for certain applications is generally off set by this strength difference.