Evaluation of Current Shear and Flexural Design Equations for FRP Reinforced Concrete Beams
Open Access
- Author:
- Brumbaugh, Mark Andrew
- Area of Honors:
- Civil Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Hassan El Chabib, Thesis Supervisor
Eric Todd Donnell, Thesis Honors Advisor - Keywords:
- FRP reinforcement
reinforced concrete beams
design standards - Abstract:
- Reinforced concrete beams provide strength and stability to reinforced concrete structures. They resist applied moment by a couple of internal forces; a compression force resisted by concrete and an equal tension force resisted by the reinforcing material to accommodate the weakness of concrete in tension. Different types of reinforcing material can be used as long as they provide the necessary tensile strength; however, the most commonly used reinforcing material in today’s market is steel bars. If not well protected, steel will be susceptible to corrosion, especially in areas where deicing salt is used, structures are exposed to harsh environments, or the structures are offshore. Corrosion reduces the area of steel bars, leading to a significant reduction in the ultimate capacity of the reinforced concrete beam and ultimately making the structure unsafe. An alternative reinforcing material is fiber-reinforced polymer (FRP) bars. FRP bars are typically composed of glass or carbon fibers encased in a matrix of resin. They have a high strength to weight ratio and high resistance to corrosion; however, they have a lower modulus of elasticity than steel and one might need different design equations to predict the shear and flexural capacities of concrete beams if such material is used. Current standards allow users to design FRP-reinforced concrete beams using equations initially developed for the design of steel-reinforced beams with slight modifications to account for the lower modulus of elasticity of FRP bars. Some of these standards provide design equations that are conservative while others provide unsafe or complicated design equations. In each case, these equations still need some improvement to accurately predict the design strengths. This study compares experimental results for beams tested in shear and flexure to those calculated using design equations provided by the American Concrete Institute (ACI 440.1R-15), the Canadian Standards Association (CSA S806-02 and CSA S806-12), ISIS Canada Design Manual 3- 2007, and the European design manuals (fib-TG9.3, 2007). The relative significance of each parameter in the design equations was investigated and refined as needed. Design equations provided by current standards were accordingly modified to better predict the shear and flexural capacity of reinforced concrete beams. The proposed modified equations perform better than the existing ones considered in this study while ensuring safety.