Structures Design
Structures Design - Transportation Innovation Fiber Reinforced Polymer (FRP) |
Overview 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:
Like any construction material, there are pros and cons to the use of FRP reinforcing:
Due diligence is encouraged 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 materials 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, specially in the last 10 years. Because of these advances, the FDOT Structures Design Office implemented its first specifications and design criteria to support the use of FRP bars and strands in major bridge components in 2016. BFRP is a newly stablished technology in the US, and continues to be refined as it matures into standard practice. This will require periodic updates to the Department Specifications and Standards. The use of these innovative materials in bridge components will keep the State of Florida on the leading edge in the design of state-of-the-art durable and cost effective transportation facilities. Usage Restrictions / Parameters When not explicitly required by the FDOT Structures Manual or shown in the Standard Plans, GFRP, BFRP and/or CFRP reinforcing bars should be considered in the following concrete components when approved by the DSDE. Refer to specific limitations within the FDOT Structures Manual, Volume 4 (FRP Guidelines)
The use of GFRP, BFRP and/or CFRP reinforcing bars in other locations are 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 components are also available for use following SDG 3.12.3 requirements. CFRP strands may be used in other prestressed concrete standard elements (FSB girders, FSU slab-beams, etc.) when required by the FDOT Structures Manual or for non-standard elements when approved by the SSDE. These usage restrictions take into consideration the following items:
Design Criteria See the following references for the application of FRP bars and strands for concrete reinforcement:
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 when not mandated 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 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. Standards The following Standard Plans and associated Instructions are available on the Standards webpage for the following applications:
The following Developmental Design Standards and associated Instructions are available on the Developmental Design Standards webpage:
Development of additional Developmental Design Standards 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. Reports for current approved procedures are available on the MAC reporting webpage. Projects: (Please contact the coordinator at the bottom of the page to submit a fast facts sheet and have your project included in the list.) Fast-Facts (First Use) sheets for selected projects in Florida are listed below:
Technology Transfer (T2) The following links to FDOT meetings, seminars and workshops are provided as background information for potential users and industry partners: 2025
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2014 FHWA FRP Composite Technology Active or recently completed FDOT sponsored research projects: BFRP Reinforcing:
Closeout Meeting Presentation (6MB) Executive Summary (1MB); Final Report (126 MB)
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:
Closeout Meeting Presentation Final Report
CFRP Prestressing:
Contact Information Steve Nolan, P.E. Assistant State Structures Design Engineer Phone: (850) 414-4272 e-mail: [email protected] |