scope:

a. Applications.

(1) Nonstructural applications. Composite materials may be used in appropriate nonstructural applications. This includes the purchase and use of existing commercial products.

(2) Secondary structural applications. When composite materials offer cost or performance advantages, they may be used for secondary structural applications. Generally such applications should be relatively small, inexpensive, and easily replaceable. Examples of such applications include handrails, grating, ladders, light posts, large pipes, small gates, and minor temperature reinforcement in thin concrete sections. Components such as these may be included in construction contracts as performance specified items, to be designed and certified by the supplier. The performance specification should identify the functional requirements, exposure conditions, durability requirements, and any restrictions on material selection. Generally, the designer should specify generic products based on consultations with several potential suppliers to determine the availability and suitability of products for such applications.

(3) Critical structural applications. Composite materials shall not be used for critical structural elements except in consultation with and as approved by CECW-E. This includes any application where failure of the composite would significantly impact life safety, or the overall structural integrity or function of the project. Examples include large gates or hybrid girders of wood/FRP or concrete/FRP. Since there are no national design codes for composite materials, each design is unique and will require special studies and design procedures, and possibly special contracting methods. This will require the involvement of suppliers, contractors, designers, and reviewers during development of the design. The project management plan should include appropriate funds and schedule for this special design effort, including appropriate expert consultation. A reliable quality assurance plan is essential for design, fabrication, and erection. To ensure acceptability of the final product, specific verification, testing, and monitoring requirements should be developed.

Purpose. This engineer technical letter (ETL) provides basic information and references on background, evaluation, and design of fiber-reinforced plastic (FRP) materials to assist structural design engineers who are considering the use of FRP on civil works projects. This information will help the engineer evaluate the suitability of FRP materials for structural applications, and will be useful in preparing performance specifications for procurement of suitable composite components and structures.

Applicability. This ETL applies to HQUSACE elements and USACE commands having responsibilities for the design of civil works projects.