Numerical investigation for the flexural strengthening of reinforced concrete beams with external prestressed HFRP sheets

Strengthening method of using HFRP (hybrid fiber reinforced polymer) has been considered to be an effective way to increase the strengthening efficiency. This paper focuses on simulating the flexural behaviors of RC (reinforced concrete) beam which strengthened by prestressed HFRP sheets. Finite element analysis is presented to validate against laboratory tests of five beams. All beams have the same rectangular cross-section geometry and are loaded under four point bending, but differed in the prestress and HFRP. The user-subroutine UMAT (User subroutine to define a material's mechanical behavior) is used for implementation of the whole model. Different material models are evaluated with respect to their ability to describe the behavior of the beams. The results show good agreement with the experimental data regarding load-displacement response, ultimate flexural capacity, ductility and failure mode. The result shows that prestressed HFRP can resist both live load and dead load of the strengthened beam, unload tensile stress of the steel and restore structural deformation, thus improve the performance of the strengthened beam.