This study investigates the behavior of fiber reinforced polymer (FRP) strengthened reinforced concrete (RC) beams under static and impact loads. The experimental program includes six beams tested in static loads and seven beams tested against impact loads. Longitudinal FRP strips and FRP U-wraps were used to strengthen these beams. The section of four beams was modified to have a curved-soffit in order to reduce the stress concentration of FRP U-wraps and provide confinement effect on longitudinal FRP strips. The experimental results showed that the proposed modification significantly increased the beam capacities as compared to their rectangular counterparts strengthened with the same amount of FRP material. In addition, this paper also provides explanations and discussions on the phenomenon of shifting of the flexure failure mode under static loads to the shear-flexure failure mode under impact loads of all the beams tested in the study, as well as the proper interpretations of the measured impact forces in the tests. From the experimental results, it is recommended that the impact force and inertial force at the very early stage of an impact event should be used to design the impact resistance.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Formation and location of the plastic hinge in an RC beam.  Verification of the distribution of inertia force.  Shear force and bending moment of an RC beam subjected to impact loads.

The paper uses the "membrane hypothesis" to formulate the confining behavior of fiber reinforced polymer (FRP) confined rectangular columns. A model was developed to calculate the strength of FRP confined rectangular concrete columns. The model was verified using a database of 190 FRP confined rectangular concrete columns. The database covers unconfined concrete strength between 18.3 MPa and 55.2 MPa and specimens with dimensions ranging from 79 mm to 305 mm and 100 mm to 305 mm for short and long sides, respectively. The performance of the proposed model shows a very good correlation with the experimental results. In addition, the strain distribution of FRP around the circumference of the rectangular sections was examined to propose an equation for predicting the actual rupture strain of FRP. The minimum corner radius of the sections is also recommended to achieve sufficient confinement.

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