Structures Design


Structures Design - Transportation Innovation

Fiber Reinforced Polymer (FRP)
Reinforcing Bars and Strands


The deterioration of reinforcing and prestressing steel within concrete is one of the prime causes of failure of concrete structures. In addition to being exposed to weather, concrete transportation structures in Florida are also commonly located in aggressive environments such as marine locations and inland water crossings where the water is acidic. Cracks in concrete create paths for the agents of the aggressive environments to reach the reinforcing and/or prestressing steel and begin the corrosive oxidation process. An innovative approach to combat this major issue is to replace traditional steel bar and strand reinforcement with Fiber Reinforced Polymer (FRP) reinforcing bars and strands. FRP reinforcing bars and strands are made from filaments or fibers held in a polymeric resin matrix binder. FRP reinforcing can be made from various types of fibers such as glass (GFRP), basalt (BFRP) or carbon (CFRP). A surface treatment is typically provided that facilitates a bond between the reinforcing and the concrete.

Beneficial characteristics of FRP reinforcing include:

  • It is highly resistant to chloride ion and chemical attack
  • Its tensile strength is greater than that of steel yet it weighs only one quarter as much
  • It is transparent to magnetic fields and radar frequencies
  • GFRP and BFRP have has low electrical and thermal conductivity

Like any construction material, there are pros and cons to the use of FRP reinforcing:

  • Due to its inelastic behavior and the emerging findings from ongoing research, current applicable design codes significantly reduce the allowable stress capacity that can be assumed when designing with FRP. Engineers must take into consideration the more stringent reduction factors in the applicable codes when designing with FRP reinforcing.
  • Due to the manufacturing processes currently in use and the progressive standardization that they are undergoing, requirements for project specific acceptance testing of FRP can be more extensive compared to those which are required for steel reinforcing bars and strands.
  • Storage and handling requirements for FRP reinforcing on the construction site can be more restrictive due to FRP's susceptibility to damage by overexposure to UV light, improper cutting or aggressive handling.
  • The initial cost of the FRP reinforcing is considerably higher than traditional steel reinforcing. However, this higher initial cost may be partially offset by a reduction in the concrete cover and the elimination of corrosion inhibiting admixtures typically used for steel reinforced concrete construction in extremely aggressive environments. A longer service life of the concrete component may also be expected if FRP reinforcing is used by reducing the need for repairs and eliminating cathodic protection or sacrificial anodes.

Due diligence must be done to ensure FRP benefits outweigh the costs of implementation for each concrete component.

Traditionally, composite materials like FRP have been used extensively in aerospace and consumer sporting goods applications where the material's high strength to weight ratios were first exploited. In the 1960s US Government agencies recognized the potential benefits that composites can provide to society's infrastructure and thus begin funding significant amounts of research in the field of FRPs. Since then advances in the field of polymers, advancements in production techniques and implementation of authoritative design guidelines have resulted in a rapid increase in usage of FRP bars and strands, especially in the last 5 years. Because of these advances, the FDOT Structures Design Office has implemented its first specifications and design criteria to support the use of FRP bars and strands in major bridge components. BFRP is an emerging technology in the US, and as such still in a development phase by the Department for Specification and Standards. The use of these innovative material in certain Florida bridge components will keep Florida on the leading edge in the design of state-of-the-art transportation facilities.

Usage Restrictions / Parameters

GFRP, BFRP and/or CFRP reinforcing bars may be used in the following concrete components when approved by the SSDE:

  • Approach Slabs
  • Bridge Decks and Bridge Deck overlays
  • Cast-in-Place Flat Slab Superstructures
  • Pile Bent Caps not in direct contact with water
  • Pier Columns and Caps not in direct contact with water
  • Retaining Walls, Noise Walls, Perimeter Walls
  • Traffic Railings
  • Pedestrian/Bicycle Railings
  • Bulkheads and Bulkhead Copings with or without Traffic or Pedestrian/Bicycle Railings
  • MSE Wall Panels
  • MSE Wall Copings with or without Traffic or Pedestrian/Bicycle Railings
  • Drainage Structures

The use of GFRP, BFRP and/or CFRP reinforcing bars in other locations will be considered on a case-by-case basis.

Developmental Standard Plans are available for Approach Slabs (GFRP Reinforced Flexible Pavement Approaches) and Gravity Walls (Option C - GFRP Reinforcement). These can be used following the approval process in FDOT Design Manual (FDM), Chapter 115.

Standard Plans for 12, 14, 18, 24 and 30 inch square piles as well as 54 and 60 inch cylinder piles with CFRP strands are available and can be used following the FDOT Structures Manual, Volume 1 Structures Design Guidelines (SDG) Table 3.5.1-1 requirements. Design Standards for precast concrete CFRP/GFRP and HSSS/GFRP sheet pile wall are also available for use following SDG 3.12 requirements. CFRP strands may be used in other prestressed concrete piles when approved by the SSDE.

These usage restrictions take into consideration the following items:

  • The criticality of the components and/or structures they are part of
  • The desirable service life of these components and/or structures
  • The historical in-service performance of these components and/or structures that were designed, detailed and constructed using the conventional reinforcing steel, prestressing steel and concretes that are currently required.
Design Criteria

See the following references for the application of FRP bars and strands for concrete reinforcement:

  • AASHTO LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete, 2nd Edition
  • AASHTO Guide Specifications for the Design of Concrete Bridge Beams Prestressed with Carbon Fiber-Reinforced Polymer (CFRP) Systems, 1st Edition
  • ACI 440.1R-15 "Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars"
  • ACI 440.4R-04 "Prestressing Concrete Structures with FRP Tendons (Reapproved 2011)"
  • ACI 440.5-08 "Specification for Construction with Fiber-Reinforced Polymer Reinforcing Bars"
  • ACI 440.6-08 "Specification for Carbon and Glass Fiber-Reinforced Polymer Bar Materials for Concrete Reinforcement"
  • ACI 440R-07 "Report on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures"
  • ICC-ES, AC454 "Fiber-reinforced Polymer (FRP) Bars for Internal Reinforcement of Concrete Members", June 2016"  

Additional design and detailing criteria are available in the FDOT Structures Manual, Volume 4 Fiber Reinforced Polymer Guidelines.

The potential use of FRP reinforcing bars or strands for a given application will be evaluated on a project by project basis. Extensive coordination with the Structures Design Office will be required in order to develop acceptable final designs. See Structures Manual, Volume 4, Fiber Reinforced Polymer Guidelines for more information.


Specifications 400, 410, 415, 450, 932 and 933 are available on the Specifications webpage  for the use of FRP reinforcing bars and strands. Additional Developmental Specifications for other concrete structural components will be written and made available on an as-needed basis.


The following Standard Plans and associated Instructions are available on the Standards webpage  for the following applications:

  • Index 455-440 - Precast Concrete CFRP/GFRP & HSSS/GFRP Sheet Pile Wall
  • Indexes 455-101 thru 455-130 - Square CFRP Prestressed Concrete Piles
  • Indexes 455-154 and 455-160 - CFRP Prestressed Concrete Cylinder Piles

The following Developmental Design Standards and associated Instructions are available on the Developmental Design Standards webpage:

  • D6011c - Gravity Wall - Option C
  • D21310 - FRP Reinforcing Bar Bending Details
  • D22900 Approach Slabs (GFRP Reinforced Flexible Pavement Approaches)
  • D22420 Traffic Railing (32" F Shape - GFRP Reinforced)

Development of additional Developmental Design Standards for Concrete Box Culverts is planned for the future.

Producer Quality Control Program

FRP producers seeking to be included on the FRP Production Facility Listing may find guidance for material acceptance on the State Materials Office Fiber Reinforced Polymer Composites webpage.

Technology Transfer (T2)

The following links to FDOT meetings, seminars and workshops are provide as background information for potential users and industry partners:





  • FDOT Transportation Symposium (June 18-20, 2018)
  • fib Congress (October 7-11, 2018)






      AASHTO Innovation Initiative (A.I.I.)

      FHWA FRP Composite Technology

      FDOT Research

      Active or recently completed FDOT sponsored research projects:

      BFRP Reinforcing:

      • BE694, Improving “Testing Protocol and Material Specifications for Basalt Fiber Reinforced Polymer Bars” (2019-2021):

      Closeout Meeting Presentation (6MB)

      Executive Summary (1MB); Final Report (126 MB)

      • STIC-0004-00A Incentive Project - BFRP Reinforcing Standardization (2018-2021):

      i.   Final Report (1 MB);   Final Report with Appendix A, B, & C (20 MB)

      ii.  Phase 1: BVD30 986-01 “Performance Evaluation of Basalt Fiber Reinforced Polymer (BFRP) Reinforcing Bars Embedded in Concrete” (2018-2019): 

      Final Report

             iii. Phase 2: BVD34 986-02 “BFRP Reinforced Bridge-Link Slab Instrumentation and Monitoring” (2019-2021):

      Final Report

              iv. Phase 3: Technology Transfer:

      2019 FDOT Transportation Symposium - FRP-RC Design Training.

      2019 HDOT Peer Exchange Seminar – BFRP-RC Standardization of Design & Materials:

      GFRP Reinforcing:

      • BDV31 977-110 “Development of GFRP Reinforced Single Slope Bridge Rail” (2019-2022) (Final Report Pending)

      Closeout Meeting Presentation      Final Report

      • BDV30 706-01 “Inspection and Monitoring of Fabrication and Construction for the West Halls River Road Bridge Replacement” (2016-2021)

      Deliverable 1A               “End of Construction Report

      Deliverable 1B & 2B      “Durability Tests (Initial & 9-months)”

      Deliverable 2A               "Six-Month Inspection Report"

      Deliverable 3B               "Durability Tests at 18 months"

      Deliverable 4                 "Two-Year Post Construction Report”

      • BDV29 977-52 “Epoxy Dowel Pile Splice Evaluation” (2019-2021)(Final Report)
      • BDV30 977-27 “Evaluation of Glass Fiber Reinforced Polymers (GFRP) Spirals in Corrosion Resistant Concrete Piles” (2018-2023)

      Deliverable 1 “Literature Review of Pile Driving System

      Deliverable 2A “Pile Impactor and Restraint Design

      Deliverable 3 “Literature Review of Spirals under Impact Loading and Bending

      Deliverable 4A & 4B "Plans for Pile Instrumentation, Testing, Design Calcs, and Specs"

      Deliverables 5 "Analytical model and Finite Element model to predict the test results

      Deliverables 6 -10: pending

      CFRP Prestressing:

      Contact Information

      Steve Nolan, P.E.
      Senior Structures Design Engineer
      Phone: (850) 414-4272