Bridge deterioration is predominantly driven by corrosion of steel components. The corrosion of steel leads to cracking in the concrete, which, in turn, results in greater exposure of the steel to further corrosion, and ultimately, a loss in a structure’s capacity and ductility. One means of achieving a longer service life, faster installation, and overall lower life cycle costs in vehicular bridges is corrosion-free fiber-reinforced polymer (FRP) reinforcement, which has a high strength-to-weight ratio.

However, FRP’s material properties differ from steel and need to be factored into the design process. FRP is a brittle material with little warning of sudden rupture. Also, FRP has a lower elastic modulus relative to steel, thus requiring more reinforcement in a given structural component to maintain the same level of deflection. Furthermore, FRP reinforcement typically has a substantially lower shear capacity compared to its steel counterpart. Current commercially available FRP materials are thermosetting in nature; therefore, construction crews cannot bend existing material into the desired shape in the field. In addition, the FRP reinforcement is more susceptible to damage during repair or modification of concrete components, and the material’s resilience during fire exposure remains unknown.

Although AASHTO has attempted to address these disadvantages through design guidance and specifications for some FRP systems, there is still a great deal of hesitancy using the material within the bridge engineering community. The reasons for the reluctance to broadly implement FRP may vary between state departments of transportation (DOTs). Therefore, the first step to improving FRP adoption is understanding these obstacles.

The objective of this pooled fund study is to identify the obstacles state DOTs are facing when determining whether FRP reinforcement is the most cost-effective alternative for vehicular bridges. Some example topics and sub-topics for FRP reinforcement are given in Figure 1. Other issues may well be discovered as a result of this pooled fund study.

The intended outcome from this effort is a prioritized list of future research the DOTs deem to be pivotal in convincing bridge owners that FRP reinforcement should be considered as an alternative to traditional reinforcement for extending bridges’ service lives well beyond the century mark. The TPF consortium can also draft guidance on how to resolve each barrier and highlight those groups best suited for resolving the existing need.  This multistate, organized approach to problem identification and resolution guidance could lead to follow-on studies whereby researchers discover the answers to the DOTs’ concerns.  

Participating states will convene in at least four meetings, either remotely or in-person, to generate a priority list of future research topics. After the first meeting, subsequent sessions will build off of the previous gatherings with additional information and insights that member state representatives gain from internal conversations within their own agencies.

Figure 1. Obstacles for State Departments of Transportation when Implementing Fiber-Reinforced Polymer Reinforcement in a Bridge

If the participating states agree, this project can also include a series of surveys distributed to non-participating states, FRP manufacturers, and precast fabricators that may have insights as to what the barriers are to implementing FRP components on a broader scale. Their input may help ensure that the identified research needs reflect both technical and implementation challenges faced across the industry. Meanwhile, the consortium may choose to review existing literature or a scan tour covering the FRP life cycle from fabrication to demolition and the successes and complications bridge owners have experienced with FRP.

Again, the focus of this study is to discover hurdles that DOTs encounter when considering FRP reinforcement in bridges. However, if sufficient funds exist, this consortium could use their collective discretion to distribute research grants for specific projects to begin answering some of the issues that are clear obstacles that DOTs face when implementing FRP reinforcement.  

For the core functions of the consortium, we are seeking 5 to 10 partners at a contribution level of $20k per year for an anticipated 2-year timeframe. Consortium participants will have key roles in selecting areas of program emphasis, as well as prioritizing specific research needs.