Inconsistencies and False Assumptions Related to the Determination of Design Values for FRP Systems

Fiber reinforced polymer (FRP) materials have been used for over half a century in the aerospace, marine and automotive industries. During the last few decades, civil and structural engineers have begun to see the advantage of these materials as a means to retrofit and rehabilitate existing structural members in buildings, bridges and other civil infrastructures. There are many guidelines and some codes that help engineers to design these systems for various structural applications. Despite the increase in acceptance of these systems there remains some major confusion related to the most fundamental part of the design process… How do you determine the characteristic values/design properties of the material? Some of the confusion stems from the assumption that all fiber reinforced polymers (FRPs) use the same method to report their design values… they do not. Or that the ASTM standards being used by the industry provide consistent design properties… they do not. Some engineers assume that following CSA S806, CSA S6-06 or ACI 440.2R-17 will get them consistent design properties… it will not. These issues have created confusion, and they have not been appropriately addressed. This paper will point out the various inconsistencies and false assumptions in more detail while presenting a suggested solution that has been in practice in other industries using FRP materials.