Evaluation of minimum thickness requirements for FRP reinforced concrete

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University of New Brunswick


Flexural design of fibre reinforced polymer (FRP) reinforced concrete members can be an iterative and time-consuming approach. Recommended minimum member thicknesses are available for design, but often lead to overly thick members. The research in this document presents an evaluation of member thickness requirements for FRP reinforced concrete flexural members ( one way slabs and beams). A review of design requirements from applicable North American design standards for FRP reinforced concrete is presented and compared with design requirements for steel reinforced concrete. Formulations for member span-to-depth (L/h) ratios are developed for flexural strength, incremental and live load deflection, crack control, creep rupture requirements, and compressive stress limits in the concrete. Shear strength and development length are not considered. An extensive parametric study is carried out to investigate all pertinent design criteria and show their effects on the applicable design requirements. Results show that flexural members designed for strength typically do not satisfy serviceability. Design is controlled mostly by serviceability related to either deflection (slabs and beams) or crack control (beams using FRP with poor bond). L / h ratios based on incremental deflection requirements provide a good starting point for design, and are used to establish recommended values of minimum member thickness as a design aid. Design examples are presented to demonstrate an efficient design procedure for FRP reinforced concrete.